Keywords
aortic dissection - myocardial infarction - percutaneous coronary intervention
Introduction
Type A aortic dissection is a life-threatening condition with a wide range of clinical
manifestations.[1] Aortic dissections can sometimes mimic an acute myocardial infarction due to similar
presenting symptoms and initial clinical investigations. Misdiagnosis in such an instance
can be catastrophic due to the immediate administration of thrombolytic and antiplatelet
agents, which theoretically increase the mortality risk in this group. We report the
case of a 52-year-old male who presented with an inferior ST-segment elevation myocardial
infarction with two drug-eluting stents (DESs) inserted prior to the diagnosis of
an acute aortic dissection.
Case Presentation
A 52-year-old gentleman presented to hospital with central chest pain, diaphoresis,
and collapse while at work. His past medical history was significant for hypertension,
and he was a current smoker. Initial electrocardiogram (ECG) by the ambulance crew
suggested inferior ST-segment elevation. He was urgently transferred to the cardiac
catheterization laboratory for primary percutaneous coronary intervention (PCI). He
was clinically in shock on arrival with a systolic blood pressure of 70 mm Hg and
a heart rate of 40 in complete heart block. Initial contrast injection suggested severe
ostial disease of the right coronary artery. A 3 mm × 30 mm XIENCE DES was inserted
into the proximal vessel with hemodynamic improvement but with some persistent ST-elevation.
The ostium appeared missed, so a second DES was deployed with both stents overlapping.
ST-segments and hemodynamics subsequently improved with a heart rate of 120. No obvious
aortic dissection was seen on the aortogram during the procedure.
The patient was transferred to the ward for observation following the procedure. He
became hypoxic requiring optiflow overnight, with episodes of hemoptysis. Clinical
examination revealed signs of pulmonary edema and a diastolic murmur. Urgent review
of the PCI images suggested possible aortic dissection ([Fig. 1]). The echocardiography revealed free-flowing aortic regurgitation with a dissection
flap visible in the ascending aorta which was confirmed on computed tomography aortogram.
Fig. 1 (A) Left ventricular aortography showing the true lumen delineated by the dissection
flap (arrow). (B) Transesophageal echocardiogram showing the right coronary artery (RCA) stent protruding
into the aorta (arrow). (C) Intraoperative picture demonstrating RCA stent protruding from the ostium (arrow).
The patient underwent an emergency aortic dissection repair with a mechanical aortic
valve replacement, ascending aorta and hemiarch replacement, and coronary bypass graft
to the right coronary artery (RCA). An intimal tear on the noncornary cusp at the
level of the sinotubular junction was found. The DESs were found protruding into the
aorta from the right coronary os and were removed ([Fig. 1]). The patient was discharged 3 weeks later with almost complete recovery in follow-up
at 6 months.
Discussion
Acute aortic dissection can be a challenging diagnosis to make in an emergency setting.
ECGs often show some degree of nonspecific ST-segment or T-wave changes, but changes
suggestive of an acute myocardial infarction in aortic dissection are rare.[2] Misdiagnosis can have potential deleterious consequences as a result of antiplatelet
and thrombolytic agents given prior to surgical repair. The involvement of the RCA
is well documented and attributed to dissection flaps more commonly originating in
the anterior aspect of the ascending aorta above the sinuses of Valsalva.[3]
Although misdiagnosis occurred in our case, it is debatable that early administration
of a DES and antiplatelet agents allowed adequate reperfusion for the myocardium to
recover from the initial shock and permit successful surgical repair. Hemodynamics,
ST-segment changes, and complete heart block all resolved once the second DES was
deployed, with a view to discharging the patient in the coming days. Had the dissection
been visualized prior to DES deployment, it is likely that the patient would have
been referred directly to the operating room without sufficient protection of the
right coronary territory. In this case, PCI acted as a bridge to a successful repair
of an acute aortic dissection complicated by an acute RCA territory infarct. The requirement
of two overlapping stents was likely secondary to the space created by the dissection
flap, displacing the true ostium. Intraoperatively, the DES could be seen protruding
into the aorta and was removed. A coronary bypass graft was placed to the mid-RCA
to ensure adequate flow which may have been compromised at the ostium due to the manipulation
of the stents.
This case highlights the importance of being vigilant in a patient who presented with
an acute myocardial infarction. The diagnosis of aortic dissection can easily be missed
in such cases. Thorough clinical examination is needed, as well as careful interpretation
of available imaging studies. Although this patient was misdiagnosed, percutaneous
coronary intervention to the RCA most likely kept the patient clinically stable until
definitive surgical management for his aortic dissection.
