A Pictorial Review of the 2020 Padua Criteria in Diagnosing Arrhythmogenic Cardiomyopathy with Insights from Native T1 Mapping

Abstract

Arrhythmogenic cardiomyopathy (ACM) is a heritable myocardial disorder characterized by progressive fibrofatty replacement, typically involving the right and/or left ventricles. The 2020 Padua Criteria offer an updated, multiparametric diagnostic framework that addresses the limitations of the 2010 Task Force Criteria. Cardiac magnetic resonance (CMR), particularly native T1 mapping, has emerged as a pivotal modality for myocardial tissue characterization in ACM. This prospective study evaluated four patients with clinically suspected ACM and 12 age-matched healthy controls. All participants underwent comprehensive CMR at 3.0 Tesla, including cine imaging, late gadolinium enhancement (LGE), and native/postcontrast T1 mapping. The Padua Criteria were applied for diagnostic classification and phenotypic characterization. Quantitative T1 mapping was employed to assess myocardial fibrosis. Application of the Padua Criteria yielded diagnoses of right-dominant ACM (n = 1), biventricular ACM (n = 2), and a borderline case (n = 1). Native T1 values were significantly elevated in the right ventricular free wall among ACM patients compared with controls (mean 1462.25 vs. 1245.51 ms, p < 0.0001). Notably, native T1 mapping identified diffuse myocardial abnormalities in cases lacking LGE. The Padua Criteria facilitates accurate phenotypic classification of ACM. Native T1 mapping enhances diagnostic sensitivity, particularly in early or subtle disease, and represents a promising noninvasive biomarker of myocardial fibrosis. Further validation in larger cohorts is warranted.

Keywords

arrhythmogenic cardiomyopathy - cardiac magnetic resonance (CMR) - late gadolinium enhancement (LGE) - native T1 mapping - Padua Criteria - right ventricular dysfunction

Background

Arrhythmogenic cardiomyopathy (ACM) is a genetically determined myocardial disorder characterized by the progressive replacement of healthy myocardium with fibrofatty tissue.[1] This pathological remodeling predominantly affects the right ventricle (RV) but may also involve the left ventricle (LV) or both, resulting in ventricular arrhythmias, heart failure, and an increased risk of sudden cardiac death, particularly in young individuals and athletes. Consequently, the disorder formerly known as arrhythmogenic right ventricular dysplasia was redefined under the more inclusive term ACM to encompass biventricular and left-dominant variations.[2]

ACM accounts for around 5% of unexpected adult fatalities,[3] with 80% of diagnoses occurring in individuals under 40 years of age. Therefore, early and accurate diagnosis of ACM is essential to guide therapeutic decision-making and prevent adverse cardiac events. Historically, the Revised Task Force Criteria of 2010 served as the diagnostic gold standard.[4] However, several limitations have been identified, most notably the lack of specific parameters for LV involvement, insufficient emphasis on tissue characterization, and dependence on subjective or operator-dependent findings.[5]

To address these gaps, the 2020 Padua Criteria were introduced as an updated, multiparametric framework that incorporates structural, functional, electrocardiographic (ECG), and tissue-based findings from both the RV and LV. Importantly, these criteria emphasize the role of cardiac magnetic resonance (CMR) imaging in detecting characteristic abnormalities and enable more comprehensive phenotypic classification of ACM into RV-dominant, biventricular, and LV-dominant subtypes.[6]

CMR is crucial in ACM diagnosis due to its capacity to detect regional wall motion anomalies, chamber volumes, and systolic function. Among CMR techniques, native T1 mapping has emerged as a promising noninvasive tool for quantifying myocardial fibrosis without the need for contrast agents. By measuring the intrinsic T1 relaxation time of myocardial tissue, native T1 mapping offers the potential to detect diffuse fibrotic changes that may not be visible on late gadolinium enhancement (LGE) imaging.[7] While its role in ischemic and nonischemic cardiomyopathies is increasingly recognized, there remains limited data on its utility in ACM, particularly in the context of the Padua Criteria.

In this study, we aimed to evaluate the application of the 2020 Padua Criteria for diagnosing and phenotyping ACM and to explore the potential of native T1 mapping in supporting tissue characterization and enhancing diagnostic accuracy.

Materials and Methods

Study Design and Population

This was a prospective, observational study conducted at the Barnard Institute of Radiology, Madras Medical College, Chennai, Tamil Nadu, India, over a 3-month period from August 2024 to October 2024. The study population included—four patients with clinical suspicion of ACM, based on history, ECG, and echocardiographic findings, and 12 healthy volunteers without a history of cardiac disease, who served as controls for imaging parameter comparisons. Informed consent was obtained from all participants. Ethical approval was granted by the institutional review board prior to study initiation.

Imaging Protocol

All participants underwent CMR imaging with a 3-Tesla magnetic resonance imaging (MRI) equipment (Magnetom Skyra, Siemens Healthineers, Erlangen, Germany). A standardized CMR procedure was employed, encompassing the subsequent sequences: T2 Half-fourier acquisition single-shot turbo spin-echo (HASTE) axial and true Fast imaging with steady-state precession (FISP) cine pictures in four-chamber, two-chamber, three-chamber, and short-axis views. In every case, T2 Short tau inversion recovery (STIR) axial and Phase sensitive inversion recovery (PSIR) postcontrast pictures were taken. Native T1 mapping was conducted in both cases and controls utilizing a modified Look-Locker inversion recovery (MOLLI) sequence[8] in short-axis slices through the apex, mid-body, and base, as well as in the four-chamber view. Retrospective ECG gating was employed for cine true FISP images, whereas prospective ECG gating was utilized for other sequences. Steady-state free precession pictures were obtained for cine imaging in standard long- and short-axis orientations. Cardiac MR protocol also included postcontrast T1 mapping and calculation of extracellular volume (ECV) fraction in all the patients.

Diagnostic Criteria and Phenotyping

The 2020 Padua Criteria were applied in a two-step diagnostic process:

1. Multiparametric assessment: Classification of RV and LV involvement based on the presence of major and minor criteria, which included morphological, functional, ECG, and tissue characterization findings[9] ([Table 1]).

2. Phenotype classification: Each patient was categorized into one of the following phenotypes: right-dominant ACM, biventricular ACM, or left-dominant ACM ([Fig. 1]).

Table 1 The 2020 Padua Criteria showing the criteria for RV and LV involvement

Category	Right ventricle (Upgraded 2010 ITF criteria)	Left ventricle (New diagnostic criteria)
I. Morphofunctional ventricular abnormalities	Major: Regional RV akinesia, dyskinesia, or bulging + either global RV dilatation (per age/sex/body size nomograms) or global RV systolic dysfunction (reduced RVEF) Minor: Regional RV akinesia, dyskinesia, or aneurysm of RV free wall	Major: Global LV systolic dysfunction (reduced EF or longitudinal strain), ± LV dilatation (increase of LV EDV) Minor: Regional LV hypokinesia or akinesia of LV free wall, septum, or both
II. Structural myocardial abnormalities	Major (by CE-CMR): Transmural LGE (stria pattern) of ≥1 RV region (inlet, outlet, apex) in ≥ 2 views. Major (by EMB): Fibrous replacement in ≥ 1 sample, without fatty tissue	Major (by CE-CMR): LV LGE (stria pattern) of ≥ 1 Bull's Eye segment in ≥ 2 views of free wall (subepicardial/midmyocardial), septum, or both (excluding septal junctional LGE).
III. Repolarization abnormalities	Major: Inverted T waves in right precordial leads (V1–V3) in individuals with complete pubertal development (absent complete RBBB) Minor: Inverted T waves in V1 and V2 (without RBBB) or in V1–V4 with complete RBBB	Minor: Inverted T waves in left precordial leads (V4–V6) in absence of complete LBBB
IV. Depolarization abnormalities	Minor: Epsilon wave in right precordial leads (V1–V3), or terminal activation duration ≥ 55 ms including R' in V1–V3 (no RBBB)	Minor: Low QRS voltages (< 0.5 mV peak to peak) in limb leads (if no obesity, emphysema, or pericardial effusion)
V. Ventricular arrhythmias	Major: Frequent RV extrasystoles (> 500/day), or VT of LBBB morphology Minor: Same as major but with inferior axis (“RVOT pattern”)	Minor: Frequent LV extrasystoles (> 500/day), or VT with RBBB morphology (“fascicular pattern”)
VI. Family history/genetics	Major: Pathologic ACM diagnosis in 1st-degree relative or identified pathogenic mutation Minor: Suspected ACM or sudden death < 35 years in 1st-degree relative, or ACM diagnosis in 2nd-degree relative	Same as RV criteria

Abbreviations: ACM, arrhythmogenic cardiomyopathy; CE-CMR, contrast-enhanced cardiac magnetic resonance; CMR, cardiac magnetic resonance; EDV, end-diastolic volume; EF, ejection fraction; EMB, endomyocardial biopsy; LBBB, left bundle branch block; LGE, late gadolinium enhancement; LV, left ventricle; RBBB, right bundle branch block; RV, right ventricle; RVOT, right ventricular outflow tract.

Note: Adapted from Corrado et al.[9]

Fig. 1 Flowchart for phenotypic characterization of arrhythmogenic cardiomyopathy (ACM).

T1 Mapping and Data Analysis

T1 relaxation times were measured in both the RV free wall and LV myocardium, as well as the interventricular septum. The region-of-interest (ROI) was carefully placed to avoid blood pool and partial volume effects.[8] Mean native T1 values were calculated for both patient and control groups. ECV fractions were calculated in patients with hematocrit values, pre- and postcontrast T1 values using a specific formula. All image postprocessing and T1 value quantification were performed using Syngo.Via software. Data were analyzed using IBM SPSS Statistics (version 29.0) and Microsoft Excel. Continuous variables (e.g., native T1 values) were expressed as mean ± standard deviation. Comparisons between patient and control groups were made using the unpaired two-tailed Student's t-test. A p-value of < 0.05 was considered statistically significant.

Results

Twelve healthy persons without cardiac illness (mean age: 42.4 years) acted as controls, and four patients (three males, one female; mean age: 39.7 years) with ACM were incorporated into this study. LGE was present in all patients except patient 4. LGE was observed in the RV free wall in all LGE-positive patients and in the LV myocardium or septum in patients with biventricular involvement.

Phenotypic Classification Using Padua Criteria

Application of the 2020 Padua Criteria enabled precise phenotypic characterization ([Table 2]):

Table 2 Summary of phenotypic classification of the patients

	Case 1	Case 2	Case 3	Case 4
RV dyskinesia with systolic dysfunction	✓	✓	✓	✓
LV systolic dysfunction		✓	✓
LGE	Only in RV	Both in RV and LV	Both in RV and LV
Ventricular arrhythmias		✓
ECG repolarization abnormalities			✓	✓
Family history				✓
ACM phenotype	Definite ARVC	Definite biventricular	Definite biventricular	Borderline ARVC
T1 and ECV elevation	Only in RV	Both in RV and LV	Both in RV and LV	Only in RV

Abbreviations: ACM, arrhythmogenic cardiomyopathy; ARVC, arrhythmogenic right ventricular cardiomyopathy; ECG, electrocardiogram; ECV, extracellular volume; LGE, late gadolinium enhancement; LV, left ventricle; RV, right ventricle.

• Patient 1: Definite right-dominant ACM

A 69-year-old male presented with a 4-month history of chest pain and palpitations. ECG showed sinus bradycardia, and echocardiography revealed RV and right ventricular outflow tract dilatation. CMR demonstrated right atrial and RV dilatation with bulging and microaneurysms of the RV free wall. Cine imaging showed RV dyskinesia and mild systolic dysfunction (right ventricular ejection fraction [RVEF]: 19%; end-diastolic volume [EDV] index: 111 mL/m²). LGE imaging revealed enhancement of the RV free wall, indicating myocardial fibrosis. Native T1 mapping showed markedly elevated values in the RV free wall (mean T1 values: 1480.66 ms), and ECV was similarly increased, supporting diffuse fibrotic involvement ([Fig. 2A–F]). The patient met two major RV criteria, including morphofunctional and structural tissue abnormalities. No LV involvement was identified. The phenotype was consistent with definite right-dominant ACM.

Fig. 2 Patient 1. (A) Electrocardiogram (ECG) showing sinus bradycardia (arrows). (B, C) Cardiac magnetic resonance (CMR) 4-chamber and short-axis views showing dilatation of right atrium (RA), right ventricle (RV) wall with bulging (arrows). (D) Late gadolinium enhancement (LGE) noted in RV free wall (arrows). (E) Pre- and (F) postcontrast T1 mapping in RV and left ventricle (LV) walls.

• Patient 2: Definite biventricular ACM

A 39-year-old male with a history of ventricular tachycardia (VT) on irregular treatment and lateral medullary syndrome presented with chest pain. ECG showed VT, and CMR demonstrated right atrial and RV dilatation with microaneurysms of the RV free wall. CMR also revealed RV dyskinesia with systolic dysfunction (RVEF: 21%; EDV index: 110 mL/m²), along with LGE in both RV and LV free walls. LV function was also mildly reduced (LVEF: 37.4%). Native T1 mapping showed elevated values in the RV free wall (mean T1 values: 1521.12 ms), and interventricular septum (mean T1 values: 1248.45 ms) ([Fig. 3A–G]); ECV was similarly increased. The patient met three major RV criteria (dyskinesia, LGE, VT) and one major and one minor LV criterion (LV systolic dysfunction, LGE). The diagnosis was consistent with definite biventricular ACM.

Fig. 3 Patient 2. (A) Electrocardiogram (ECG) showing wide QRS complexes indicating ventricular tachycardia (arrows). (B, C) Cardiac magnetic resonance (CMR) 4-chamber and short-axis views showing severe thinning of right ventricle (RV) wall with bulging (arrows). (D, E) Late gadolinium enhancement (LGE) noted in RV free wall (arrows) and in left ventricle (LV). (F) Pre- and (G) postcontrast T1 mapping in RV and LV walls.

• Patient 3: Definite biventricular ACM

A 24-year-old female presented with chest pain and giddiness. ECG showed ventricular premature complexes, T-wave inversions (TWIs), and right bundle branch block (RBBB). CMR revealed dilatation of the right heart with mild RV free wall bulging. CMR also showed dyskinesia and mild RV systolic dysfunction (RVEF: 39.8%; EDV index: 122 mL/m²), with LGE in the septum and RV free wall. LV function was also mildly reduced (LVEF: 46%). Native T1 values and ECV were elevated in both the RV (mean T1 values: 1453.75 ms) and septum (mean T1 values: 1341.66 ms), indicating diffuse myocardial fibrosis ([Fig. 4A–G]). The patient satisfied two major and one minor RV criteria (dyskinesia, LGE, RBBB) and one major and one minor LV criterion (LV systolic dysfunction, LGE). The phenotype was consistent with definite biventricular ACM.

Fig. 4 Patient 3. (A) Electrocardiogram (ECG) showing wide ventricular premature complexes (VPCs), T-wave inversion, and right bundle branch block (RBBB) in V1-V4 leads (arrows). (B, C) Cardiac magnetic resonance (CMR) 4-chamber and short-axis views showing the microaneurysms of right ventricle (RV) free wall (arrows). (D, E) Late gadolinium enhancement (LGE) noted in RV free wall (arrows) and in septum. (F) Pre- and (G) postcontrast T1 mapping in RV and left ventricle (LV) walls.

• Patient 4: Borderline right-dominant ACM

A 27-year-old male presented with exertional dyspnea and a family history of sudden cardiac death in his father. ECG showed TWI and RBBB. CMR demonstrated RV and right atrium dilatation with striations noted in RV free wall (accordion sign)[10] and microaneurysms of RV free wall. CMR also showed severely reduced RVEF (RVEF: 18.7%; EDV index: 121 mL/m²), with no evidence of LGE. However, native T1 and ECV were elevated in the RV free wall (mean T1 values: 1395.41 ms), suggesting early fibrotic changes ([Fig. 5A–F]). This patient met one major and two minor RV criteria (dyskinesia, family history, RBBB). No LV involvement was noted. The case was classified as borderline right dominant ACM.

Fig. 5 Patient 4. (A) Electrocardiogram (ECG) showing T-wave inversion and right bundle branch block (RBBB) in V1-V4 (arrows). (B, C) Cardiac magnetic resonance (CMR) 4-chamber and short-axis views showing striations (accordion sign) of right ventricle (RV) wall with microaneurysms (arrows). (D) Absent late gadolinium enhancement (LGE). (E) Pre- and (F) postcontrast T1 mapping in RV and left ventricle (LV) walls.

Cardiac MR cine images of the cases are included in the supplementary file ([Supplementary Material S1]).

Native T1 Mapping

The mean native T1 value in the RV free wall of the patient group was 1462.25 ms, significantly higher than that of the control group (1245.51 ms, p < 0.0001) ([Fig. 6A]). The mean native T1 value in the LV myocardium among controls was 1186.34 ms.[11] Two patients (patients 2 and 3) with suspected LV involvement demonstrated elevated T1 values in the interventricular septum and LV free wall ([Fig. 6B]). Elevated ECV values corresponded with regions of elevated native T1 in all patients.

Fig. 6 Bar chart showing mean native T1 values in right ventricle (RV) (A) and left ventricle (LV) (B) between patients and controls.

Discussion

This study demonstrates the utility of the 2020 Padua Criteria in the diagnosis and phenotypic classification of ACM and highlights the promising role of native T1 mapping as a noninvasive tool for myocardial tissue characterization.

The 2020 Padua Criteria, unlike the 2010 Revised Task Force Criteria, incorporate biventricular and left-dominant forms of ACM, addressing a significant limitation in earlier diagnostic frameworks. By adopting a multiparametric approach combining structural, functional, ECG, and tissue-based imaging features, the Padua Criteria allow for more nuanced and accurate classification. In our cohort, this approach enabled us to classify patients as right-dominant, biventricular, or borderline ACM, in line with the spectrum of phenotypes recognized in recent literature.

Native T1 mapping findings correlated well with LGE and phenotypic features. All four patients showed elevated native T1 values in the RV free wall, and those with suspected LV involvement (patients 2 and 3) exhibited elevated T1 values in the septum and LV free wall, consistent with the presence of diffuse myocardial fibrosis. These findings reinforce the growing evidence that native T1 mapping can detect early or subtle fibrotic changes, even when LGE is absent or inconclusive.[12]

Importantly, patient 4 demonstrated elevated RV T1 values despite the absence of LGE, suggesting that native T1 mapping may be more sensitive in early disease or nonscar fibrosis, providing incremental diagnostic value. These findings align with previous work by Georgiopoulos et al, who emphasized the role of T1 mapping in characterizing myocardial abnormalities in patients and at-risk family members.[7]

Native T1 mapping also offers practical advantages: it is noninvasive, does not require contrast, and is reproducible. This is particularly valuable in younger patients, those with renal dysfunction, or when serial imaging is needed.[13]

This study has some limitations. The small sample size restricts generalizability, and the lack of long-term follow-up data prevents prognostic assessment. Additionally, interobserver variability in ROI placement for T1 measurements, though minimized by standardized protocols, could influence results. Larger, multicenter studies are needed to validate our findings and determine optimal T1 cutoffs for ACM diagnosis.

Future work should aim to define reference T1 values for the RV, which are currently less standardized than LV values. Integrate ECV quantification more systematically across phenotypes. Explore the use of native T1 mapping in family screening and early detection strategies for ACM.[14]

Conclusion

The 2020 Padua Criteria provide a comprehensive and flexible framework for the diagnosis and phenotypic classification of ACM, effectively addressing the limitations of earlier diagnostic systems, particularly with respect to left ventricular involvement.

Our findings support the integration of native T1 mapping into the diagnostic pathway for ACM.[15] Elevated native T1 values in the RV free wall and septum were consistent with myocardial fibrosis and correlated with Padua-defined phenotypes. Notably, native T1 mapping demonstrated potential utility even in cases without visible LGE, highlighting its sensitivity in detecting early or diffuse myocardial involvement.

Incorporating native T1 mapping into standard cardiac MRI protocols may enhance diagnostic confidence, facilitate earlier detection, and reduce reliance on invasive methods such as myocardial biopsy. Further large-scale studies are warranted to standardize its application and establish diagnostic thresholds for routine clinical use.

Conflict of Interest

None declared.

Note

The manuscript was earlier presented by Dr. Thiagarajan Veerappan as part of poster presentation in AOCR 2025 at Chennai on January 24, 2025. Abstract ID – ABS0288.

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Publication History

Article published online:
09 December 2025