Keywords
coronary revascularization - aortic valve surgery - mitral valve surgery - tricuspid
valve surgery - left ventricular assist device - heart transplantation
Introduction
We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)
approach for a systematic literature review. The MEDLINE database was searched using
the following search terms combined with the publication date being between January
1, 2019, and December 31, 2019, for the different sections of this article: Coronary
Artery Bypass Grafting; Aortic Valve; TAVI; Aortic Valve Disease; Mitral Valve Surgery;
MitraClip; Tricuspid Valve; Aortic Aneurysm; Aortic dissection; LVAD; Mechanical Circulatory
Support and Heart Transplantation; clinical trial. [Supplementary Fig. S1] (online only) shows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses
diagram for the literature review. We selected publications based on their value for
indications, decision making, and patient information. Articles with focus on individual
technical details without relevant information for the above-described goals were
omitted.
Surgical Treatment of Coronary Artery Disease
Surgical Treatment of Coronary Artery Disease
In 2019, publications in the field can be separated into four categories: (1) studies
addressing coronary artery bypass grafting (CABG) versus percutaneous coronary intervention
(PCI), (2) new diagnostic tools for diagnosis and treatment of coronary artery disease
(CAD), (3) technical aspects of CABG conduct, and (4) the role of medical therapy
in CABG patients.
CABG versus PCI
Recent years have been filled with publications addressing comparisons of CABG and
PCI. Two years ago, a large patient-level meta-analysis of the most pertinent randomized
trials demonstrated a survival advantage for CABG compared with PCI in multivessel
disease. This CABG survival advantage can be observed repeatedly in various trials
and registry analyses and seems to be dependent on the severity of CAD.[1] This recognition is also reflected in the 2018 revised guidelines for myocardial
revascularization.[2]
In 2019, we published an investigation exploring the mechanisms through which PCI
and CABG mediate their treatment effect.[3] [Fig. 1A] shows autopsy examinations of coronary artery trees relating the degree of coronary
artery stenosis to its likelihood to occlude a vessel ([Fig. 1A], I) or to cause an infarction ([Fig. 1A], II). The image gives rise to three important recognitions. First, the likelihood
for vessel occlusion increases with the severity of coronary artery stenoses present.
Second, there were more occlusions than infarctions caused, an observation supporting
the well-known phenomenon of a clinically silent vessel occlusion, which is generally
explained by the presence of collaterals.[4] Third, the majority of myocardial infarctions are caused by nonflow limiting coronary
artery stenoses (86% by stenosis less than 70%). The last recognition gives rise to
the question whether PCI (independent of stent type) can be expected to prevent new-onset
myocardial infarction in a statistically relevant dimension. This question receives
clinical support from repeated trials reporting no survival benefit and no impact
of PCI on new myocardial infarctions in comparison to medical therapy (Stergiopoulos
et al[5] and see later). Our article also illustrates the inability of randomized studies
to demonstrate that ischemia testing may predict outcome after myocardial revascularization
(with either PCI or CABG, see later and the original article for more details). We
were then able to show that the repeatedly demonstrated survival advantage of CABG
compared with PCI was visible every time, and there was also a difference in the rate
of new myocardial infarctions. Thus, it is our suggestion that coronary bypass surgery
prolongs life not primarily by revascularization but first and foremost by surgical
collateralization (i.e., by providing protection against new infarctions, [Fig. 1B]). We thereby revive the concept that has been proposed already 10 years ago by Jeon
et al[6] who demonstrated that the insertion of a bypass graft is usually distal to the site
of thrombotic vessel occlusion.
Fig. 1 Main findings of 2019 publications on invasive treatment of coronary artery disease.
(A) Relationship between coronary artery stenosis severity in pathological vessel segments
and vessel occlusion (I) or infarct occurrence (II). Relating the occurrence of infarction
to vessel stenosis shows that vessels with more than 70% stenosis cause only 14% of
all myocardial infarctions. (B) Schematic illustration how bypass grafting but not stenting can protect against
infarction from not flow-relevant stenoses. (C) Kaplan–Meier's survival of patients with end-stage renal failure having received
either CABG or PCI.[14] (Reproduced with permission.) (D) Primary end point of the EXCEL trial at 5 years.[15] (Reproduced with permission.) (E) Survival free of CV events in the MASS II patient population (including CAD patients
with medical, PCI, and/or PCI treatment) depending on the ability to induce ischemia
by stress testing.[20] (Reproduced with permission of CC-BY license.) CABG, coronary artery bypass grafting;
CV, Cardiovascular; PCI, percutaneous coronary intervention.
There were many publications in 2019 comparing PCI and CABG, which also present data
suggestive of a link between mortality and new myocardial infarctions. A meta-analysis
of 15 studies in more than 13,000 patients with a follow-up of up to 5 years demonstrated
that CABG provides a lasting impact versus PCI in the occurrence of new myocardial
infarctions during follow-up.[7] This reduction in infarct occurrence was largest after 5 years and was not diminished
by the use of drug-eluting stents.
The FREEDOM trial presented its 8-year outcomes with again a significant survival
advantage of CABG over PCI in patients with double- and triple-vessel disease and
diabetes mellitus.[8] While this 8-year follow-up of the original trial patients only recorded survival
information, a single-center analysis on 430 freedom-like patients, who received either
medical, interventional, or surgical therapy, demonstrated the lowest long-term mortality
and the lowest rate of new myocardial infarctions in the CABG group.[9]
A meta-analysis of 20 studies comparing PCI and CABG in patients with reduced ejection
fraction and at least 1-year follow-up (more than 54,000 patients) demonstrated again
a mortality benefit for CABG over PCI, again associated with a reduction in new-onset
myocardial infarctions.[10]
In the setting of non-ST segment elevation myocardial infarction (NSTEMI), an Israeli
multicenter analysis on more than 5,000 patients, of which 15% were operated, demonstrated
447 risk-adjusted patient pairs that CABG provided a survival advantage associated
with a reduction in new-onset myocardial infarctions.[11] Another single-center analysis on 1,100 multivessel disease patients with NSTEMI
also demonstrated a survival advantage for CABG.[12] Although the authors did not present information on myocardial infarctions during
follow-up, the survival impact was visible once the SYNTAX score exceeded 22.
Assuming that more complex CAD carries greater risk for new infarctions, this rationale
is able to explain the 10-year results from the SYNTAX trial,[13] where complete follow-up was generated by the participating centers without additional
funding. The only end point that was monitored demonstrated a nonsignificant difference
in survival at 10 years, but a very much significant survival advantage for CABG if
the SYNTAX score was more than 32. Examining the survival curves demonstrates that
after 5 years, the curves for PCI and CABG narrow again. One vague speculation may
be that bypass graft occlusions over time (most grafts in SYNTAX were veins) may be
responsible (infarct protection would get lost with graft occlusion).
Another group of patients with high risk for myocardial infarctions are patients with
chronic kidney disease. A Veterans Affairs hospital registry analysis on almost 1,000
patients having received CABG or PCI in patients with chronic kidney disease who became
dialysis dependent within the next 5 years again revealed a survival advantage for
the CABG population ([Fig. 1C]).[14]
Finally, the 5-year results of the EXCEL trial were presented. The trial compared
CABG versus PCI in patients with left main CAD and a SYNTAX score less than 32.[15] The primary outcome consisted of death myocardial infarction and stroke and was
reported as not significantly different at 5 years ([Fig. 1D]). Since there had been previous discussions on the definition of myocardial infarction
used by this trial[16] and the fact that all-cause mortality at 5 years was significantly lower with CABG,
a fierce discussion arose, resulting in one of the main surgeons of the trial withdrawing
his authorship from the 5-year article. The discussion culminated in the European
Association for Cardio-Thoracic Surgery (EACTS) withdrawing its support for the current
European guidelines on myocardial revascularization. At the time of submission, the
controversy was still unresolved. (Press release Prof. Pagano, Secretary General of
the EACTS: https://www.eacts.org/eacts-responds-to-bbc-newsnights-investigation-on-the-excel-trial/, December 9, 2019). Irrespective of this discussion and of the definition for myocardial
infarction used, the published data already contain information that supports the
connection between death and new-onset myocardial infarctions. In the time from 30
days to 5 years, death rate was significantly higher in the PCI group (12.4 vs. 9.1%
in CABG) which was associated with a myocardial infarction rate that was almost twice
as high as in the PCI group (6.8 vs. 3.5% in CABG).[15] Finally, the NOBLE trial, assessing PCI and CABG for left main disease in a similar
patient population as EXCEL demonstrated less myocardial infarctions with CABG at
5 years, although in this study, there was no difference in mortality between the
groups.[17]
The recognition, that a survival advantage may primarily be mediated by protection
against new infarctions, may be sobering, but the notion is not new.[5]
[18] To assess the impact of revascularization according to current guideline recommendations
on outcome in patients with relevant CAD and evidence for ischemia, the ISCHEMIA trial
was conducted. The trial compared a conservative, medically treated arm with an invasive
treatment arm consisting of three quarters of PCI and one quarter of CABG patients.
The final article has just been published. The primary end point (consisting of cardiovascular
death, myocardial infarction, hospitalization for unexpected angina, heart failure,
or survived resuscitated cardiac arrest) confirmed previous findings that the invasive
strategy was not better than conservative therapy at 5 years (although curves crossed
at 3 years) and that there was no difference at all in all-cause mortality over the
5 years.
A similar conclusion was drawn by the STICH trial 10-year results, in which all patients
where viability testing was performed were assessed. The study concluded that knowledge
of viability or nonviability did not affect the survival advantage provided by CABG,
again questioning the role of revascularization as main mechanism for the survival
advantage associated with CABG.[19]
Finally, a follow-up analysis of the MASS II trial, where patients were randomized
between 1995 and 2000 to medical therapy PCI or CABG, analyzed the role of ischemia
detection by electrocardiogram stress testing (Bruce protocol). The authors found
that the detection of ischemia did not predict the probability of survival free of
cardiovascular events ([Fig. 1E]).[20]
In summary, it appears reasonable to conclude from the data in 2019 alone that a prognostic
impact of all current therapies for the treatment of stable CAD (now also termed chronic
coronary syndromes) stems mainly from surgical collateralization and probably less
so from revascularization. Thus, it may be time to rethink our terminology of our
invasive treatment strategy (specifically for CABG) and to assess patients with chronic
coronary syndromes not only by their number of severe coronary lesions but also by
their risk to develop new myocardial infarctions.
New Tools for the Diagnosis and Treatment of Coronary Artery Disease
After the SYNTAX III Revolution trial demonstrated the feasibility to provide treatment
recommendation for invasive therapy based on coronary computed tomography (CT) imaging
in patients with triple-vessel disease,[21] the same group demonstrated in 2019 that surgeons are able to plan CABG surgery
based on the sole availability of CT coronary images in the majority of cases (80%).[22] A trial to test its practical feasibility is underway.
Another new diagnostic tool for the planning of CABG surgery is based on functional
flow assessments over coronary stenoses such as the determination of the fractional
flow reserve (FFR). The GRAFFITI trial randomized 172 patients in a group with classic
assessment of bypass graft targets and one group where FFR assessment was used for
graft selection.[23] The classic group received on average one graft more than the FFR group (three vs.
two grafts). Within the 12 months follow-up, there was no difference in adverse events,
mortality, and importantly in patency rates ([Fig. 2A]). In contrast, the IMPAG trial assessed 199 coronary lesions in 67 patients by FFR
measurement.[24] They then performed fully arterial revascularization as judged by classic eyeball
assessment. There was no mortality and no adverse events within the 6 months follow-up.
Patency was controlled after 6 months with coronary CT and outcomes related to FFR
values before surgery. The authors found that 96% of all grafts were classified as
perfect if the FFR value was less than 0.79. If the FFR value was more than 0.79,
the fraction of occluded grafts was up to 20% in the sequential setting and more than
50% in a single graft setting.
Fig. 2 Main findings of 2019 publications on the conduct of coronary bypass surgery. (A) Main illustration of the GRAFITTI trial, assessing the impact of using FFR assessment
for bypass grafting.[23] (Reproduced with permission.) (B) Long-term survival of the entire GOPCABE trial patient population (off-pump vs.
on-pump in the elderly) compared the age-matched German population.[27] (Reproduced with permission.) (C) (I) All-cause mortality of the ART trial comparing bilateral versus single internal
thoracic artery grafting.[31] (Reproduced with permission.) (II) All-cause mortality for patients with single
or bilateral internal thoracic artery grafting of the ART trial surgeon who included
the most patients and who had the lowest crossover rate.[32] (Reproduced with permission.) (D) Mortality hazard ratios for different drug classes used in the treatment of patients
having received coronary bypass grafting in Sweden (data from the SWEDEHEART registry).
Statins had the largest impact on survival.[34] (Reproduced with permission.) FFR, fractional flow reserve.
Considering our surgical collateralization hypothesis, the important information is
that in both trials earlier, bypass grafting irrespective of FFR value did not increase
adverse events. Graft occlusions were silent. Thus, even a 50% chance of a graft remaining
open may be considered an additional piece of protection against new infarctions.[3]
Technical Aspects of CABG Conduct
The issue of graft patency and its related morbidity moves center stage if it comes
to technical aspects of CABG conduct. The controversy regarding off-pump's ability
to provide similar precision, completeness of revascularization, and patency of grafts
were fueled by several publications in 2019. A subanalysis of the EXCEL trial comparing
on-pump to off-pump patients revealed inferior survival in the off-pump patients.[25] In contrast, a German analysis suggests that off-pump surgery may be superior to
on-pump surgery in patients with previous coronary bypass surgery.[26] Finally, the German GOPCABE trial compared off- and on-pumps in the elderly patients.
The 5-year outcome showed no difference between groups but demonstrated that the long-term
survival of the combined operative cohort was better than that of the age-matched
German population ([Fig. 2B]).[27]
A series of large registry studies then demonstrated in 2019 that fully arterial revascularization
is associated with a survival benefit and increased patency rates.[28]
[29]
[30] The 10-year results of the ART trial may serve as perfect example illustrating the
above-described controversy. The trial randomized more than 3,000 patients to the
use of the left thoracic artery plus radial or vein grafts or the use of bilateral
thoracic arteries plus vein or radial artery grafts. The intention-to-treat primary
end point of death from any cause at 10 years demonstrated equal outcome ([Fig. 2C], I). The as-treated subanalysis of single arterial versus multiple arterial bypass
grafting then demonstrated a significant survival advantage for multiple arterial
grafts, suggesting an impact of the conduct of surgery.[31] Most importantly, the trial demonstrated that if the highest volume of surgeon's
outcomes were assessed (he/she had the lowest crossover rate from double to single
internal thoracic artery use and performed 95% of cases off-pump), there was a significant
survival advantage for the use of bilateral thoracic arteries ([Fig. 2C], II).[32] These findings demonstrated again, what many other publications have suggested before,
that individual surgical precision is a critical factor for optimal long-term outcome.
The Role of Medical Therapy in CABG Patients
The importance of medical therapy for patients having received coronary bypass grafting
has already been stressed in the recently renewed European Society of Cardiology guidelines
on coronary revascularization. In 2019, the TiCAB trial did not demonstrate an advantage
of adding ticagrelor to aspirin in patients fresh after coronary bypass surgery.[33]
One of the most interesting observations, this year, came from the Swedeheart registry,
where the investigators demonstrated a 40% risk reduction in mortality by using statins
(and also using renin–angiotensin–aldosterone system inhibitors) postoperatively ([Fig. 2D]).[34] Again, a treatment strategy reducing the risk of myocardial infarction is associated
with a survival advantage.
The main findings of 2019 publications on surgical treatment for CAD are:
-
Superiority of CABG over PCI appears to be due to surgical collateralization and infarct
protection.
-
The prognostic relevance of revascularization in chronic coronary syndromes is still
questionable.
-
Coronary CT has the potential to suffice for CABG planning.
-
Fully arterial CABG plus optimal surgical competence appears to be associated with
the best long-term survival.
-
Medical therapy is important after CABG, specifically the use of statins.
Aortic Valve Surgery
TAVI versus SAVR
In 2019, the contest between transcatheter aortic valve implantation (TAVI) and surgical
aortic valve replacement (SAVR) continued. Two randomized trials presented their primary
outcome in patients with low operative risk (i.e., Society of Thoracic Surgery [STS]
score < 3%). The Evolut Low Risk trial randomized 1,400 patients to either conventional
surgery or transfemoral TAVI using the Evolut R, the Evolut Pro, or the CoreValve
prosthesis and demonstrated equal outcome of the primary end point of death or disabling
stroke ([Fig. 3A]).[35] There was a trend toward less adverse events periprocedurally. However, the difference
was not significant. The other trial was the PARTNER 3 study that randomized nearly
1,000 patients to either SAVR or TAVI using the transfemoral Sapien 3 prosthesis.[36] The mean STS score was 1.9%. In this trial, the combined end point of death, stroke,
or rehospitalization at 12 months was superior for TAVI ([Fig. 3B]). The difference was also visible in the single end points, although not significant
for mortality.
Fig. 3 Main findings of 2019 publications on aortic valve surgery. (A) Primary outcome of the Evolut Low Risk trial.[35] (Reproduced with permission.) (B) Primary outcome of the PARTNER 3 trial.[36] (Reproduced with permission.) (C) Landmark analysis of the first 2 and the following 3 years of the PARTNER II trial.[38] (Reproduced with permission.) (D) Death from any cause (left panel) and MACE (right panel) of a propensity core matched
analysis of an Italian registry comparing TAVI and SAVR at 5 years.[39] (Reproduced with permission.) (E) Primary outcome (combined end point: A and all-cause death: B) of the RECOVERY trial
comparing early SAVR in asymptomatic patients with aortic stenosis versus conservative
(according to current guidelines) treatment.[47] (Reproduced with permission.) MACE, major adverse cardiac events; SAVR, surgical
aortic valve replacement; TAVI, transcatheter aortic valve implantation.
A meta-analysis then summarized the data of all available prospective randomized trials
of all risk categories.[37] While mortality was never significantly different between TAVI and SAVR in the individual
trials, the combined assessment presented significantly lower mortality with TAVI
(p = 0.03). This advantage was exclusively caused by patients receiving transfemoral
TAVI. In addition, TAVI patients presented with less periprocedural renal failure,
atrial fibrillation but more need for pacemaker implantation, paravalvular leaks,
and vascular complications. In addition, there was a trend toward more endocarditis
in the TAVI population, although the incidence in general was low.
While it appears from these data, that TAVI is certainly not inferior (if not superior)
to SAVR in the perioperative period, long-term follow-ups are still missing (for obvious
reasons). In 2019, the 5-year outcomes for PARTNER II were presented and an Italian
registry demonstrated a propensity-matched analysis. While in PARTNER II, where the
Sapien XT valve was randomized to classic surgery in patients with intermediate risk,
the primary outcome of death disabling stroke was not significantly different at 5
years, a landmark analysis demonstrated that the curves crossed between 2 and 3 years
and that surgery provided significantly improved outcome in the second half ([Fig. 3C]).[38] The Italian registry analysis, where 650 risk-adjusted patient pairs out of 8,000
patients with either TAVI or SAVR were compared, also demonstrated a significant survival
advantage for SAVR at 5 years ([Fig. 3D]).[39] Finally, a single-center propensity-matched comparison in low-risk patients (109
pairs, EuroSCORE II < 4%) suggested similar outcomes between TAVI and SAVR at 1 year,
but a remarkable (and significant) survival advantage for SAVR after 5 years.[40] Thus, longer follow-up appears necessary.
While durability of tissue valves may be one explanation for this possible difference
at 5 years, one summary of the available information[41] and one outcome study of the NOTION trial illustrated that signs for structural
valve deterioration were even lower in the TAVI population, although the rates of
valve failure were low and the same in both groups.[42] Thus, the differences in mortality observed in several studies[39]
[40]
[43]
[44] may not be explained by differences in midterm durability.
Aortic stenosis is often accompanied by other cardiac pathologies. The presence of
concomitant mitral stenosis was analyzed in 971 TAVI patients over an 8-year period
in a single-center study.[45] The authors found signs of mitral stenosis in 176 of almost 1,000 patients. They
could demonstrate that the presence of mitral stenosis increased the rate of stroke
and cardiovascular death depending on the severity of the stenosis.
Another issue related to adverse events, specifically in TAVI patients, is the occurrence
of prosthetic valve thrombosis, which is occurring about four times as often as in
classic surgery.[46] In 2019, the GALILEO trial published its primary outcome, where aspirin plus rivaroxaban
was compared with a double platelet inhibition strategy post-TAVI. The trial confirmed
the high occurrence of valve thrombosis in the TAVI population and also demonstrated
the efficacy of anticoagulation to prevent or treat this problem. However, the trial
also demonstrated increased mortality in the group with aspirin plus rivaroxaban,
creating a “catch-22 situation” for a not insignificant fraction of patients receiving
TAVI. Taking these findings together, it underscores the need for individualized and
joint decision making and comprehensive consenting of patients with severe aortic
stenosis.
Classic Aortic Valve Surgery
The first prospective randomized evidence for the efficacy of SAVR in asymptomatic
patients with severe aortic stenosis emerged in 2019. The RECOVERY trial[47] randomized 145 asymptomatic patients with flow velocities above 4.5 m/s or mean
pressure gradients above 50 mm Hg randomized to early surgery to a conservative strategy
until a guideline indication for valve replacement occurred. In the surgical group,
95% of patients received aortic valve replacement within 2 months. During the 8-year
follow-up, three quarters of patients in the conservative group required surgery for
meeting guideline-conform indications. The primary end point consisted of operative
mortality or cardiovascular death during follow-up. It was significantly higher in
the conservative group, as was all-cause mortality ([Fig. 3E]).
Another interesting analysis in this context is a single-center observational study
of 614 patients above 75 years of age having received classic aortic valve replacement.[48] The authors compared these surgical patients with 61,000 persons of the normal population
(1–100 matched). The analysis demonstrated that those patients having survived surgery
had normal life expectancy thereafter and that mortality was only higher in the year
of surgery. These data support the efficacy of mechanical elimination of an aortic
valve stenosis and the excellent long-term outcomes of classic aortic valve replacement.
With respect to valve durability, there were many publications in 2019 mainly focused
on the gray zone in the guidelines (i.e., patients at age between 50 and 70 years).
All these publications demonstrated that biological prostheses are not associated
with a poorer survival compared with mechanical prostheses.[49]
[50]
[51]
[52]
[53]
[54] They presented less bleeding and thrombotic events but required higher rates of
reoperation.[50]
[51]
[54] These findings were also true for patients with end-stage renal failure.[50]
[52]
[53]
The main findings of 2019 publications on surgical treatment of aortic valve disease
are:
-
Transfemoral TAVI may be superior to surgical AVR in the periprocedural/perioperative
period.
-
This advantage appears to get lost over time and surgery may become superior at 5
years.
-
In patients receiving classic SAVR, the selection of a biological prosthesis does
not limit prognosis. This also seems to be true in patients with end-stage renal failure.
Mitral and Tricuspid Valves Surgery
Mitral and Tricuspid Valves Surgery
Mitral Valve
The last year in mitral valve surgery was mainly characterized by discussions around
the COAPT and the MITRA FR trials.[55]
[56] The COAPT trial had demonstrated superior outcome for MitraClip versus medical therapy
in patients with functional mitral regurgitation (MR) including a significant survival
advantage, while MITRA FR did not find any differences between MitraClip and medical
therapy even at 2 years.[56] However, we[57] and others[58] have questioned plausibility of the COAPT results because of inconsistent echocardiographic
measurements. The authors had not provided the regurgitant volume in their original
publication in 2018.[59] We had suggested that based on the available data, it was impossible for these patients
to generate a forward cardiac output because the expected regurgitant volume would
be equal to total stroke volume. In 2019, the authors then presented values that fully
support our concern (regurgitation volume: device group: 59.7 ± 21.0 mL and control
group: 59.9 ± 23.5 mL).[55] They went on to suggest the concept of disproportionate MR as possible explanation,[60] where the relationship of effective regurgitant orifice (ERO) and the regurgitant
volume is not supposed to be proportionate any more (specifically in smaller ventricles).
Although the idea of this disproportionate MR may be intriguing, the math still does
not add up. If MR is disproportionate because there is more regurgitant volume than
expected from the ERO, calculated cardiac outputs will become even more negative,
which is not possible. If the MR is disproportionate because the regurgitant volume
is lower than expected from the ERO, the MR may not be relevant anymore. Considering
these plausibility problems for the echocardiographical quantification of functional
MR, patient selection based on echocardiography (especially for those deriving the
suggested prognostic effect) appears very difficult.
Harmel et al published a study addressing the surgical treatment of functional MR.[61] The authors analyzed around 100 consecutive patients who either received an annuloplasty
alone or an annuloplasty plus an additional subvalvular technique, anchoring the two
papillary muscles independently to the implanted annuloplasty ring. The authors demonstrated
superior outcome for the subvalvular group, where improved 5-year survival was associated
with less return of severe MR ([Fig. 4A]). Although the technique does not fully address the underlying pathology of FMR,[62] it importantly demonstrates that a subvalvular technique, stabilizing the geometric
dimension of a repair, results in better durability, which may be associated with
a survival advantage. Thus, this study underscores that future trials on FMR still
require a surgical arm.
Fig. 4 Main findings of 2019 publications on mitral and tricuspid valves surgery. (A) Survival (left panel) and freedom from severe mitral regurgitation in patients with
functional mitral regurgitation either received annuloplasty only or annuloplasty
plus a subvalvular technique.[61] (Reproduced with permission.) (B) Survival (I) and posttreatment prevalence of mitral regurgitation (II) in patients
who received MitraClip or surgical treatment for structural mitral regurgitation.[63] (Reproduced with permission.) (C) Meta-analysis of trials comparing mitral valve replacement (MVR) with mitral valve
repair (MVr) in patients with structural MR.[64] (Reproduced with permission.) (D) Freedom from structural valve deterioration (SVD) after bioprosthetic valve replacement
in patients who did (BB) or did not (non-BB) receive β blocker therapy.[65] (Reproduced with permission.) (E) Long-term survival in risk-adjusted patients who received either tricuspid valve
repair or replacement for tricuspid regurgitation.[67] (Reproduced with permission.)
While the earlier investigations addressed functional MR, Buzzatti et al compared
100 MitraClip-treated with 206 surgically treated patients with an age older than
75 years, an STS score of less than 8% and with structural MR as underlying pathology.
The authors found a trend toward less periprocedural complications in the MitraClip
group but a tremendous survival advantage for surgery after 5 years, with the curves
diverging after 1 year ([Fig. 4B]).[63] These results suggest that mitral valve repair remains the gold standard for operable
patients even at older age.
A meta-analysis of 12 studies having included patients with structural MR compared
outcomes for mitral valve repair with replacement.[64] In almost 3,000 patients, the authors demonstrated a significant survival advantage
for mitral valve repair, which was again independent of age ([Fig. 4C]). In case mitral valve replacement is required, a risk-adjusted analysis on 138
patients with biological mitral valve prostheses then demonstrated that patients who
received β blocker therapy showed higher freedom from structural valve deterioration
([Fig. 4D]).[65] If mitral valve surgery is indicated in the presence of previous cardiac surgery,
the valve can be approached through a miniright-sided thoracotomy. This type of surgery
performed mainly on the fibrillating heart was compared with classic redo sternotomy
by Patel et al.[66] Propensity matching of reoperative mitral valve cases (90 patient pairs out of more
than 400) demonstrated no difference in survival, but faster mobilization, earlier
discharge and a trend toward lower operating times in the minimally invasive group.
Tricuspid Valve
A comparison of repair and replacement was also published for the tricuspid valve.
The Mayo Clinic analyzed their database between 1993 and 2013 and presented a risk-adjusted
comparison of 1,735 patients with tricuspid repair with 806 patients with tricuspid
replacement.[67] The authors demonstrated a significantly better survival after 15 years in the repair
group and suggest performing repair whenever possible ([Fig. 4E]).
Another publication confirmed previous studies and guideline recommendations, by demonstrating
that adding tricuspid repair to an otherwise indicated cardiac operation does not
increase operative risk and leads to improvement in right ventricular function during
follow-up.[68] Their analysis was performed on 300 risk-adjusted patient pairs, where tricuspid
regurgitation was mild to moderate and there was evidence for annulus dilatation.
A Texan publication then demonstrated their experience with 95 isolated tricuspid
valve operations out of 685 operations addressing the tricuspid valve between 2007
and 2017. In the isolated cohort, the authors found a mortality of 3.2%, without having
lost a single patient in the past 6 years. The authors suggest that tricuspid valve
surgery is safe today and that these outcomes should serve as benchmark for interventional
procedures.[69]
A provocative analysis was then published from the Massachusetts General Hospital,
questioning a survival advantage possibly provided by tricuspid valve surgery.[70] The authors performed a risk-adjusted comparison of 171 patients having received
tricuspid surgery with more than 3,000 patients treated conservatively. While the
direct comparison showed superiority of surgery, considering an immortal time bias,
the difference was no longer present. The authors also did not find a difference between
repair and replacement. While this information was prominently published, the immortal
time bias comparison contains only 19 surgical patients. In addition, the authors
write ∼85% repairs but show 85% replacement. Finally, the findings are in stark contrast
with a previous publication from the Brigham and Women's Hospital suggesting a survival
impact of tricuspid surgery.
The main findings of 2019 for mitral and tricuspid valves surgery are:
-
The debate on MitraClip efficacy continues, with COAPT echodata still being inconsistent.
-
Surgical treatment of functional MR may still afford a survival advantage if the proper
surgical technique is applied.
-
Surgery appears superior to MitraClip in structural MR.
-
Repair of the mitral or the tricuspid valves may afford a survival advantage over
replacement.
-
β blocker therapy may improve durability of biological prosthesis in the mitral position.
Surgery of the Aorta
Three publications in 2019 addressed generally important information on the treatment
of acute type A dissections. First, a Japanese registry analysis on more than 10,000
patients demonstrated that surgical treatment of type A dissections has improved over
the years despite the fact that patients have become older. They also demonstrate
that patients receiving replacement of the ascending aorta plus partial arch only
tended to have better outcomes than those with full arch replacement. However, this
difference became smaller over time indicating increased competence and handling of
these difficult surgical cases.[71]
An analysis from the University of Stanford assessed their experience of 345 patients
with type A dissections focusing on preexisting neurological injury.[72] The authors found that preexisting neurological injury increased perioperative risk,
but the duration of symptoms before surgery did not influence perioperative mortality
or potential neurological recovery. Thus, they suggest operating on patients irrespective
of preexisting neurological injuries.
Another complication of type A dissections is the development of mesenteric ischemia.
Yang et al demonstrated their experience on 602 patients between 1996 and 2017 from
the University of Michigan in Ann Arbor.[73] Mesenteric ischemia was present in 82 patients. The authors demonstrate that interventional
fenestration or stent implantation aimed at relieving bowel ischemia before the thoracic
aorta is addressed results in excellent outcomes. All patients were ischemia was successfully
relieved could be operated on the thoracic aorta at normal risk.
Surgery for Terminal Heart Failure
Surgery for Terminal Heart Failure
Important new information was published in 2019 in the field of terminal heart failure.
The MOMENTUM 3 trial, in which the centrifugal pump HeartMate 3 was compared with
the axial-flow pump HeartMate II published its final report.[74] The authors demonstrated a significant reduction in strokes, pump thromboses, and
gastrointestinal bleedings with the new HeartMate 3 ([Fig. 5A]).
Fig. 5 Main findings of 2019 publications on surgery for terminal heart failure. (A) Forest plot for main outcomes of the MOMENTUM 3 trial comparing the HeartMate II
to the HeartMate 3 device.[74] (Reproduced with permission.) (B) Suggested angiotensin receptor-mediated mechanism for gastrointestinal neoangiogenesis
associated with nonpulsatile ventricular assist device therapy.[75] (Reproduced with permission.) (C) Survival in patients having undergone heart transplantation as primary or redo (separated
in to previous heart, previous LVAD, or previous heart transplantation) surgery.[79] (Reproduced with permission.) (D) Survival after heart transplantation in patients having received organs from brain-dead
or circulatory-death donors.[81] (Reproduced with permission.) LVAD, left ventricular assist device.
Gastrointestinal bleedings in the context of continuous flow ventricular assist devices
are considered to be caused by arteriovenous malformations. Converse et al analyzed
a series of 111 patients for gastrointestinal bleedings and demonstrated a 60% reduction
in bleeding risk when ACE inhibitors were part of the patients' medication. The authors
suggest that the inhibition of an angiotensin receptor-mediated mechanism reduces
the induction of arteriovenous malformations ([Fig. 5B]).[75]
A consensus paper of the European Association of Cardio-Thoracic Surgery then summarized
current recommendations for ventricular assist device use. It documents that long-term
mechanical support is an established therapy for terminal heart failure.[76]
The use of intramyocardial injections of mesenchymal stem cells has been suggested
to improve contractile recovery during left ventricular support. The efficacy of this
treatment was tested by the American surgical research network, Cardiothoracic Surgical
Trials Network in a prospective randomized trial including 159 patients.[77] Despite great expectations, injection of stem cells into mechanically supported
failing hearts did not generate a detectable effect within the 6 months observation
period.
The use of mechanical support increased in recent years because suitable donor organ
is often not readily available (i.e., bridge to transplantation due to organ shortage).
An analysis of the United Network for Organ Sharing analyzed the impact of previous
mechanical support on heart transplantation outcomes. On more than 5,000 patients
who received a heart transplantation between 2008 and 2015, a risk-adjusted comparison
of patients transplanted from assist devices with patients primarily transplanted
was performed. The authors identified the presence of a left ventricular assist device
(LVAD) as significant risk factor. Long-term survival was worse in patients with previous
mechanical support.[78] A second analysis also analyzed the same database, but between 2005 and 2017. They
identified more than 14,000 patients with heart transplantations and identified not
only the presence of an LVAD but also previous cardiac surgery as risk factors. Patients
who had previous heart transplantations had the worst survival ([Fig. 5C]).[79] The authors suggest to critically consider the presence of an LVAD in the context
of donor heart allocation.
Other options against organ shortage are directed at increasing the donor pool. An
analysis from Boston, where 44 lungs or hearts of hepatitis C positive donors were
transplanted combined with a 4-week antiviral treatment strategy, demonstrated normal
long-term results without hepatitis C infection of the recipient.[80]
The current strategy in heart transplantation is the use of brain-dead (i.e., heart
beating) donors. With the advent of the organ care system, the use of hearts from
circulatory-death donors became possible. Here, the heart of a circulatory-death donor
is implanted into the in vitro perfusion system and recovery of function is assessed.
Hearts with adequate recovery may be used for transplantation. In 2019, an Australian
center presented their experience with this technique.[81] The center explanted 33 organs for clinical use and it was possible to transplant
23 of those hearts successfully. With the exception of one early death, all patients
having received those organs survived the first 4 years ([Fig. 5D]). Given the successful experience of others,[82] this technique is an attractive perspective in heart transplantation
