Magnetic resonance imaging findings in patients meeting task force criteria for arrhythmogenic right ventricular dysplasia

Prognostic value of right ventricular trabecular complexity in patients with arrhythmogenic cardiomyopathy

OBJECTIVES

The present study aimed to investigate the incremental prognostic value of the right ventricular fractal dimension (FD), a novel marker of myocardial trabecular complexity by cardiac magnetic resonance (CMR) in patients with arrhythmogenic cardiomyopathy (ACM).

METHODS

Consecutive patients with ACM undergoing CMR were followed up for major cardiac events, including sudden cardiac death, aborted cardiac arrest, and appropriate implantable cardioverter defibrillator intervention. Prognosis prediction was compared by Cox regression analysis. We established a multivariable model supplemented with RV FD and evaluated its discrimination by Harrell's C-statistic. We compared the category-free, continuous net reclassification improvement (cNRI) and integrated discrimination index (IDI) before and after the addition of FD.

RESULTS

A total of 105 patients were prospectively included from three centers and followed up for a median of 60 (48, 66) months; experienced 36 major cardiac events were recorded. Trabecular FD displayed a strong unadjusted association with major cardiac events (p < 0.05). In the multivariable Cox regression analysis, RV maximal apical FD maintained an independent association with major cardiac events (hazard ratio, 1.31 (1.11-1.55), p < 0.002). The Hosmer-Lemeshow goodness of fit test displayed good fit (X2 = 0.68, p = 0.99). Diagnostic performance was significantly improved after the addition of RV maximal apical FD to the multivariable baseline model, and the continuous net reclassification improvement increased 21% (p = 0.001), and the integrated discrimination index improved 16% (p = 0.045).

CONCLUSIONS

In patients with ACM, CMR-assessed myocardial trabecular complexity was independently correlated with adverse cardiovascular events and provided incremental prognostic value.

CLINICAL RELEVANCE STATEMENT

The application of FD values for assessing RV myocardial trabeculae may become an accessible and promising parameter in monitoring and early diagnosis of risk factors for adverse cardiovascular events in patients with ACM.

KEY POINTS

• Ventricular trabecular morphology, a novel quantitative marker by CMR, has been explored for the first time to determine the severity of ACM. • Patients with higher maximal apical fractal dimension of RV displayed significantly higher cumulative incidence of major cardiac events. • RV maximal apical FD was independently associated with major cardiac events and provided incremental prognostic value in patients with ACM.

3D Fractal Dimension Analysis: Prognostic Value of Right Ventricular Trabecular Complexity in Participants with Arrhythmogenic Cardiomyopathy

BACKGROUND

Arrhythmogenic cardiomyopathy (ACM) is characterized by progressive myocardial fibro-fatty infiltration accompanied by trabecular disarray. Traditionally, two-dimensional (2D) instead of 3D fractal dimension (FD) analysis has been used to evaluate trabecular disarray. However, the prognostic value of trabecular disorder assessed by 3D FD measurement remains unclear.

PURPOSE

To investigate the prognostic value of right ventricular trabecular complexity in ACM patients using 3D FD analysis based on cardiac MR cine images.

STUDY TYPE

Retrospective.

POPULATION

85 ACM patients (mean age: 45 ± 17 years, 52 male).

FIELD STRENGTH/SEQUENCE

3.0T/cine imaging, T2-short tau inversion recovery (T2-STIR), and late gadolinium enhancement (LGE).

ASSESSMENT

Using cine images, RV (right ventricular) volumetric and functional parameters were obtained. RV trabecular complexity was measured with 3D fractal analysis by box-counting method to calculate 3D-FD. Cox and logistic regression models were established to evaluate the prognostic value of 3D-FD for major adverse cardiac events (MACE).

STATISTICAL TESTS

Cox regression and logistic regression to explore the prognostic value of 3D-FD. C-index, time-dependent receiver operating characteristic (ROC) curves and area under the ROC curve (AUC) to evaluate the incremental value of 3D-FD. Intraclass correlation coefficient for interobserver variability. P < 0.05 indicated statistical significance.

RESULTS

26 MACE were recorded during the 60 month follow-up (interquartile range: 48-67 months). RV 3D-FD significantly differed between ACM patients with MACE (2.67, interquartile range: 2.51 ~ 2.81) and without (2.52, interquartile range: 2.40 ~ 2.67) and was a significant independent risk factor for MACE (hazard ratio, 1.02; 95% confidence interval: 1.01, 1.04). In addition, prognostic model fitness was significantly improved after adding 3D-FD to RV global longitudinal strain, LV involvement, and 5-year risk score separately.

DATA CONCLUSION

The myocardial trabecular complexity assessed through 3D FD analysis was found associated with MACE and provided incremental prognostic value beyond conventional ACM risk factors.

EVIDENCE LEVEL

4 TECHNICAL EFFICACY: Stage 1.

The Many Faces of Arrhythmogenic Cardiomyopathy: An Overview

Arrhythmogenic cardiomyopathy (AC) is a disease that involves electromechanical uncoupling of cardiomyocytes. This leads to characteristic histologic changes that ultimately lead to the arrhythmogenic clinical features of the disease. Initially thought to affect the right ventricle predominantly, more recent data show that it can affect both the ventricles or the left ventricle alone. Throughout the recent era, diagnostic modalities and criteria for AC have continued to evolve and our understanding of its clinical features in different age groups as well as the genotype to the phenotype correlations have improved. In this review, we set out to detail the epidemiology, etiologies, presentations, evaluation, and management of AC across the age continuum.

Clinical and Genetic Characteristics of Arrhythmogenic Right Ventricular Cardiomyopathy Patients: A Single-Center Experience

Background

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited progressive cardiomyopathy. We aimed to define the long-term clinical outcome and genetic characteristics of patients and family members with positive genetic tests for ARVC in a single tertiary care cardiac center in Saudi Arabia.

Methods

We enrolled 46 subjects in the study, including 23 index-patients (probands) with ARVC based on the revised 2010 ARVC Task Force Criteria (TFC) and 23 family members who underwent a genetic test for the ARVC between 2016 and 2020.

Results

Of the probands, 17 (73.9%) were males with a mean age at presentation of 24.95 ± 13.9 years (7 to 55 years). Predominant symptoms were palpitations in 14 patients (60.9%), and syncope in 10 patients (43.47%). Sustained ventricular tachycardia (VT) was documented in 12 patients (52.2%). The mean left ventricular ejection fraction (LVEF) by echocardiogram was 52.81±6.311% (30-55%), and the mean right ventricular ejection fraction (RVEF) by cardiac MRI was 41.3±11.37% (23-64%). Implantable cardioverter-defibrillator (ICD) implantation was performed in 17 patients (73.9%), and over a mean follow-up of 13.65 ± 6.83 years, appropriate ICD therapy was noted in 12 patients (52.2%). Genetic variants were identified in 33 subjects (71.7%), 16 patients and 17 family members, with the most common variant of plakophilin 2 (PKP2) in 27 subjects (81.8%).

Conclusions

ARVC occurs during early adulthood in Saudi patients. It is associated with a significant arrhythmia burden in these patients. The PKP2 gene is the most common gene defect in Saudi patients, consistent with what is observed in other nations. We reported in this study two novel variants in PKP2 and desmocollin 2 (DSC2) genes. Genetic counseling is needed to include all first-degree family members for early diagnosis and management of the disease in our country.

Arrhythmogenic right ventricular cardiomyopathy and sports activity: from molecular pathways in diseased hearts to new insights into the athletic heart mimicry

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disease associated with a high risk of sudden cardiac death. Among other factors, physical exercise has been clearly identified as a strong determinant of phenotypic expression of the disease, arrhythmia risk, and disease progression. Because of this, current guidelines advise that individuals with ARVC should not participate in competitive or frequent high-intensity endurance exercise. Exercise-induced electrical and morphological para-physiological remodelling (the so-called 'athlete's heart') may mimic several of the classic features of ARVC. Therefore, the current International Task Force Criteria for disease diagnosis may not perform as well in athletes. Clear adjudication between the two conditions is often a real challenge, with false positives, that may lead to unnecessary treatments, and false negatives, which may leave patients unprotected, both of which are equally inacceptable. This review aims to summarize the molecular interactions caused by physical activity in inducing cardiac structural alterations, and the impact of sports on arrhythmia occurrence and other clinical consequences in patients with ARVC, and help the physicians in setting the two conditions apart.

Cardiac Magnetic Resonance Imaging Macroscopic Fibro-Fatty Infiltration of the Myocardium in Pediatric Patients with Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia

Background: Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is an inherited, progressive form of cardiomyopathy, which is characterized by fibrofatty replacement of the myocardium. While the gold standard for diagnosis remains pathologic evaluation of biopsy, advances in noninvasive imaging, including cardiac magnetic resonance imaging (CMRI), have led to improved clinical diagnosis.Case report: We report three additional cases of pediatric patients that have pathologically confirmed ARVC/D with CMRI images, demonstrating extensive macroscopic fatty infiltration of the right and left ventricular myocardium. The identification using CMRI allowed timely transplantation and patient survival.Conclusion: Our study is designed to highlight how fibrofatty changes are minimal using CMRI in the pediatric population and how this can be a valuable tool to provide an additional method of diagnosis.

Potential role of imaging markers in predicting future disease expression of arrhythmogenic cardiomyopathy

Aim: To evaluate the predictive accuracy of trabecular hypertrophy/derangement and late gadolinium enhancement in predicting diagnosis of arrhythmogenic cardiomyopathy (AC). Materials & methods: Fifty-nine suspected AC patients were evaluated. To evaluate the ability of these markers to detect patients fulfilling definite diagnosis at 4-year follow-up, sensitivity (Se), specificity (Sp), positive and negative predictive value (PPV and NPV) and predictive accuracy (PA) were calculated. Results: Presence of trabecular hypertrophy/derangement showed high NPV, while late gadolinium enhancement at cardiac MRI high Sp, NPV and PA. Their combination with symptoms and/or revised Task Force Criteria showed a high Sp, NPV and PA for definitive diagnosis during follow-up. Conclusion: In suspected AC patients, the absence of these markers allows to identify those with lower risk of disease progression.

Right Ventricular Strain Predicts Structural Disease Progression in Patients With Arrhythmogenic Right Ventricular Cardiomyopathy

Background

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited condition associated with ventricular arrhythmias and myocardial dysfunction; however, limited data exist on identifying patients at highest risk. The purpose of the study was to determine whether measures of right ventricular (RV) dysfunction on echocardiogram including RV strain were predictive of structural disease progression in ARVC.

Methods and Results

A retrospective analysis of serial echocardiograms from 40 patients fulfilling 2010 task force criteria for ARVC was performed to assess structural progression defined by an increase in proximal RV outflow tract dimensions (parasternal short or long axis) or decrease in RV fractional area change. Echocardiograms were analyzed for RV free‐wall peak longitudinal systolic strain using 2‐dimensional speckle tracking. Risk of structural progression and 5‐year change in RV outflow tract measurements were compared with baseline RV strain. Of the 40 ARVC patients, 61% had structural progression with an increase in the mean parasternal short‐axis RV outflow tract dimension from 36.2 to 38.5 mm (P=0.022) and 68% by increase in parasternal long‐axis RV outflow tract dimension from 36.1 to 39.2 mm (P=0.001). RV fractional area change remained stable over time. Baseline RV strain was significantly associated with the risk of structural progression and 5‐year rate of change. Patients with an RV strain more positive than −20% had a higher risk (odds ratio: 18.4; 95% CI, 2.7–125.8; P=0.003) of structural progression.

Conclusions

RV free wall strain is associated with the rate of structural progression in patients with ARVC. It may be a useful marker in determining which patients require closer follow‐up and treatment.

Screening relatives in arrhythmogenic right ventricular cardiomyopathy: yield of imaging and electrical investigations

AIMS

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disease and presymptomatic screening of relatives is recommended. In 2010, the Task Force Criteria (TFC2010) introduced specific diagnostic imaging parameters. The aim of the study was to evaluate the diagnostic yield of family screening and the value of different diagnostic modalities.

METHODS AND RESULTS

Family evaluation, including cardiac magnetic resonance (CMR), is routinely offered to ARVC relatives at our institution. We retrospectively registered baseline characteristics, symptomatology, and results of non-invasive examinations from 2010 to 2016 and assessed the findings according to TFC2010. A total of 286 relatives (150 females; age 12-76 years; 251 first-degree) were included. A total of 103 (36%) individuals reported cardiovascular symptoms. The non-invasive workup showed that 101 (35%) relatives had ≥1 positive parameter on signal-averaged electrocardiogram (ECG), 40 (14%) had abnormal findings on Holter monitoring, 36 (13%) fulfilled an ECG criterion, six (2%) fulfilled CMR criteria, and echocardiographic abnormalities was seen in one (0.3%) relative. In total, 21 (7% overall; 13% among gene-positive subgroup) relatives were diagnosed with ARVC and 78 (27% overall; 49% among gene-positive subgroup) with borderline ARVC based on the combined non-invasive evaluations. Family history and electrical investigations alone diagnosed 20 out of 21 (95%) ARVC cases and 73 out of 78 (94%) borderline cases.

CONCLUSION

Consecutive evaluation of ARVC relatives diagnosed 7% with definite and 27% with borderline ARVC according to the TFC2010. Screening relatives for electrical abnormalities with 12 lead ECG, signal-averaged ECG, and Holter monitoring was more sensitive than imaging modalities.

Diagnostic Differentiation Between Arrhythmogenic Cardiomyopathy and Athlete's Heart by Using Imaging

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an important cause of sudden cardiac death (SCD) in youth and athletes. In the last decade, several studies focused on right ventricular (RV) remodeling in athletes and revealed that features of the physiological adaptation of the right heart to training, such as RV dilation, may overlap with those of ARVC. Therefore, a careful multiparametric evaluation is required for differential diagnosis in order to avoid false diagnosis of ARVC or, in contrast, fail to identify the risk of causing SCD. This review summarizes physiological adaptation of the RV to exercise and describes features that could help distinguishing between athlete's heart and ARVC.

Regional Strain by Cardiac Magnetic Resonance Imaging Improves Detection of Right Ventricular Scar Compared With Late Gadolinium Enhancement on a Multimodality Scar Evaluation in Patients With Arrhythmogenic Right Ventricular Cardiomyopathy

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy is an inherited cardiomyopathy characterized by fibrofatty replacement of right ventricular myocardium resulting in reentrant ventricular tachycardia (VT). Cardiac magnetic resonance imaging (CMR) can noninvasively measure regional abnormalities using tissue-tracking strain as well as late gadolinium enhancement (LGE). In this study, we examine arrhythmogenic substrate using regional CMR strain, LGE, and electroanatomic mapping (EAM) in arrhythmogenic right ventricular cardiomyopathy patients presenting for VT ablation.

METHODS AND RESULTS

Twenty-one patients underwent right ventricular endocardial EAM, whereas 17 underwent epicardial EAM, to detect dense scar (<0.5 mV) as well as CMR study within 12 months. Quantitative regional strain analysis was performed in all 21 patients, although the presence of LGE was visually examined in 17 patients. Strain was lower in segments with dense scar on endocardial and epicardial EAM (-9.7±4.1 versus -7.3±4.0, and -9.8±2.8 versus -7.6±3.8; P<0.05), in segments with LGE scar (-9.9±4.4 versus -6.0±3.6; P=0.001), and at VT culprit sites (-7.4±3.7 versus -10.1±4.1; P<0.001), compared with the rest of right ventricular. On patient-clustered analysis, a unit increase in strain was associated with 21% and 18% decreased odds of scar on endocardial and epicardial EAM, respectively, 17% decreased odds of colocalizing VT culprit site, and 43% decreased odds of scar on LGE-CMR ( P<0.05 for all). LGE and EAM demonstrated poor agreement with κ=0.18 (endocardial, n=17) and κ=0.06 (epicardial, n=13). Only 8 (15%) VT termination sites exhibited LGE.

CONCLUSIONS

Regional myocardial strain on cine CMR improves detection of arrhythmogenic VT substrate compared with LGE. This may enhance diagnostic accuracy of CMR in arrhythmogenic right ventricular cardiomyopathy without the need for invasive procedures and facilitate the planning of VT ablation procedures.

Misdiagnosis of ARVC leading to inappropriate ICD implant and subsequent ICD removal - lessons learned

INTRODUCTION

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited progressive cardiomyopathy characterized by frequent life-threatening arrhythmias. The diagnosis of ARVC is challenging and is on the basis of a set of major and minor criteria as described by the modified Task Force Criteria (TFC). We report our clinical experience in a series of patients who were misdiagnosed with ARVC and subsequently underwent removal of their implantable cardioverter defibrillator (ICD) after a re-evaluation at our center.

METHODS AND RESULTS

We studied 12 patients who were misdiagnosed with ARVC and had ICD implantation before our assessment. All patients had a repeat evaluation and were scored according to TFC before ICD removal. Cardiac magnetic resonance imaging (CMR) studies performed at outside institutions during the initial evaluation were reported abnormal and classified as meeting major TFC in ninety percent of patients. The most common abnormality reported was fatty infiltration of the right ventricular (RV) free wall and/or presence of focal intra-myocardial fat in six patients (50%). On re-evaluation, none of these findings fulfilled the TFC for the diagnosis.

CONCLUSION

This study demonstrated that high dependence on misinterpretation of CMR along with a misunderstanding of the TFC evaluation are the main reasons for the misdiagnosis of ARVC. Despite the updated criteria for almost a decade, this study reminds that the diagnosis of ARVC is complex and hence careful TFC evaluation and consideration of multiple cardiac test results should be the focused approach for clinicians when confronted with suspected ARVC patients.

The Prognostic Value of Right Ventricular Deformation Imaging in Early Arrhythmogenic Right Ventricular Cardiomyopathy

OBJECTIVES

The aim of this study was to investigate the prognostic value of echocardiographic deformation imaging in arrhythmogenic right ventricular cardiomyopathy (ARVC) to optimize family screening protocols.

BACKGROUND

ARVC is characterized by variable disease expressivity among family members, which complicates family screening protocols. Previous reports have shown that echocardiographic deformation imaging detects abnormal right ventricular (RV) deformation in the absence of established disease expression in ARVC.

METHODS

First-degree relatives of patients with ARVC were evaluated according to 2010 task force criteria, including RV deformation imaging (n = 128). Relatives fulfilling structural task force criteria were excluded for further analysis. At baseline, deformation patterns of the subtricuspid region were scored as type I (normal deformation), type II (delayed onset, decreased systolic peak, and post-systolic shortening), or type III (systolic stretching and large post-systolic shortening). The final study population comprised relatives who underwent a second evaluation during follow-up. Disease progression was defined as the development of a new 2010 task force criterion during follow-up that was absent at baseline.

RESULTS

Sixty-five relatives underwent a second evaluation after a mean follow-up period of 3.7 ± 2.1 years. At baseline, 28 relatives (43%) had normal deformation (type I), and 37 relatives (57%) had abnormal deformation (type II or III) in the subtricuspid region. Disease progression occurred in 4% of the relatives with normal deformation at baseline and in 43% of the relatives with abnormal deformation at baseline (p < 0.001). Positive and negative predictive values of abnormal deformation were, respectively, 43% (95% confidence interval: 27% to 61%) and 96% (95% confidence interval: 82% to 100%).

CONCLUSIONS

Normal RV deformation in the subtricuspid region is associated with absence of disease progression during nearly 4-year follow-up in relatives of patients with ARVC. Abnormal RV deformation seems to precede the established signs of ARVC. RV deformation imaging may potentially play an important role in ARVC family screening protocols.

Fibrofatty Changes: Incidence at Cardiac MR Imaging in Patients with Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy

Purpose To determine the incidence of ventricular fatty replacement and late gadolinium enhancement (LGE) at cardiac magnetic resonance (MR) imaging in patients with arrhythmogenic right ventricular (RV) dysplasia/cardiomyopathy (ARVD/C) and the relationship of these findings to disease severity. Materials and Methods This was a retrospective institutional review board-approved HIPAA-compliant study. All subjects provided written informed consent. Seventy-six patients with ARVD/C were enrolled from 2002 to 2012. Quantitative and qualitative cardiac MR imaging analyses of the RV and the left ventricle (LV) were performed to determine cardiac MR imaging-specific Task Force Criteria (TFC) and non-TFC features (ARVD/C-type pattern of fatty infiltration and/or nonischemic pattern LGE). Patients were separated into four groups on the basis of cardiac MR imaging TFC: (a) patients with major cardiac MR imaging criteria, (b) patients with minor criteria, (c) patients with partial criteria, and (d) patients with no criterion. Continuous variables were compared by using the independent Student t test and analysis of variance. Categoric variables were compared by using the Fisher exact test. Results Of 76 patients (mean age, 34.2 years ± 14 [standard deviation]; 51.3% men), 42 met major cardiac MR imaging criteria, seven met minor criteria, seven met partial criteria, and 20 met no criterion. Most probands (36 [80.0%] of 45) met major or minor cardiac MR imaging criteria. Only 13 (41.9%) of 31 family members met any cardiac MR imaging criterion. The most common non-TFC MR imaging features were RV fatty infiltration (28.9%) and LV LGE (35.5%). Non-TFC cardiac MR imaging features were seen in 88.1% of subjects with major criteria, in 28.6% of those with minor criteria, in 71.4% of those with partial criteria, and in 10.0% of those with no criteria. Conclusion In this large cohort of patients with ARVD/C, non-TFC findings of ventricular fatty infiltration and LGE were frequent and were most often found in those who met major cardiac MR imaging criteria and in probands. (©) RSNA, 2016 Online supplemental material is available for this article.

Noninvasive Multimodality Imaging in ARVD/C

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a familial cardiomyopathy resulting in progressive right ventricular (RV) dysfunction and malignant ventricular arrhythmias. Although ARVD/C is generally considered an inherited cardiomyopathy, the arrhythmogenic nature of the disease is striking. Affected individuals typically present in the second to fourth decade of life with arrhythmias originating from the right ventricle. Over the past decade, pathogenic ARVD/C-causing mutations have been identified in 5 genes encoding the cardiac desmosome. Disruption of the desmosomal connection system between cardiomyocytes may be represented structurally by ventricular enlargement, global or regional contraction abnormalities, RV aneurysms, or fibrofatty replacement. These abnormalities are typically observed in predilection areas, including the subtricuspid region, basal RV free wall, and left ventricular posterolateral wall. As such, structural and functional abnormalities on cardiac imaging constitute an important diagnostic criterion for the disease. This paper discusses the current status and role of echocardiography, cardiac magnetic resonance imaging, and computed tomography for suspected ARVD/C.

Right ventricular strain by MR quantitatively identifies regional dysfunction in patients with arrhythmogenic right ventricular cardiomyopathy

BACKGROUND

Analysis of regional wall motion of the right ventricle (RV) is primarily qualitative with large interobserver variation in clinical practice. Thus, the purpose of this study was to use feature tracking to analyze regional wall motion abnormalities in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC).

METHODS

We enrolled 110 subjects (39 overt ARVC [mutation+/phenotype+] (35.5%), 40 preclinical ARVC [mutation+/phenotype-] (36.3%), and 31 control subjects (28.2%)). Cine steady state free precession cardiac MR was performed with temporal resolution ≤40 ms in the horizontal long axis (HLA), axial, and short axis directions. Regional strain was analyzed using feature tracking software and reproducibility was assessed by means of intraclass correlation coefficient. Dunnett's test was used in univariate analysis for comparisons to control subjects; cumulative odds logistic regression was used for minimally and fully adjusted multivariate models.

RESULTS

Strain was significantly impaired in overt ARVC compared with control subjects both globally (P < 0.01) and regionally (all segments of HLA view, P < 0.01). In the HLA view, regional reproducibility was excellent within (intraclass correlation coefficient [ICC] = 0.81) and moderate between (ICC = 0.62) observers. Using a threshold of -31% subtricuspid strain in the HLA view, the sensitivity and specificity for overt ARVC were 75.0% and 78.2%, respectively. In multivariable analysis involving all three groups, subtricuspid strain less than -31% (beta = 1.38; P = 0.014) and RV end diastolic volume index (beta = 0.06; P = 0.001) were significant predictors of disease presence.

CONCLUSION

RV strain can be reproducibly assessed with MR feature tracking, and regional strain is abnormal in overt ARVC compared with control subjects.

Right Ventricular Outflow Tract Arrhythmias: Benign Or Early Stage Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia?

Ventricular arrhythmias (VAs) arising from the right ventricular outflow tract (RVOT) are a common and heterogeneous entity. Idiopathic right ventricular arrhythmias (IdioVAs) are generally benign, with excellent ablation outcomes and long-term arrhythmia-free survival, and must be distinguished from other conditions associated with VAs arising from the right ventricle: the differential diagnosis with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is therefore crucial because VAs are one of the most important causes of sudden cardiac death (SCD) in young individuals even with early stage of the disease. Radiofrequency catheter ablation (RFCA) is a current option for the treatment of VAs but important differences must be considered in terms of indication, purposes and procedural strategies in the treatment of the two conditions. In this review, we comprehensively discuss clinical and electrophysiological features, diagnostic and therapeutic techniques in a compared analysis of these two entities.

Yield of serial evaluation in at-risk family members of patients with ARVD/C

BACKGROUND

Incomplete penetrance and variable expressivity of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) complicate family screening.

OBJECTIVES

The objective of the present study was to determine the optimal approach to longitudinal follow-up regarding: 1) screening interval; and 2) testing strategy in at-risk relatives of ARVD/C patients.

METHODS

We included 117 relatives (45% male, age 33.3 ± 16.3 years) from 64 families who were at risk of developing ARVD/C by virtue of their familial predisposition (72% mutation carriers [92% plakophilin-2]; 28% first-degree relatives of a mutation-negative proband). Subjects were evaluated by electrocardiography (ECG), Holter monitoring, signal-averaged ECG, and cardiac magnetic resonance (CMR). Disease progression was defined as the development of a new criterion by the 2010 Task Force Criteria (not the "Hamid criteria") at last follow-up that was absent at enrollment.

RESULTS

At first evaluation, 43 subjects (37%) fulfilled an ARVD/C diagnosis according to the 2010 Task Force Criteria. Among the remaining 74 subjects (63%), 11 of 37 (30%) with complete re-evaluation experienced disease progression during 4.1 ± 2.3 years of follow-up. Electrical progression (n = 10 [27%], including by ECG [14%], Holter monitoring [11%], or signal-averaged ECG [14%]) was more frequently observed than structural progression (n = 1 [3%] on CMR). All 5 patients (14%) with clinical ARVD/C diagnosis at last follow-up had an abnormal ECG or Holter monitor recording, and the only patient with an abnormal CMR already had an abnormal ECG at enrollment.

CONCLUSIONS

Over a mean follow-up of 4 years, our study showed that: 1) almost one-third of at-risk relatives have electrical progression; 2) structural progression is rare; and 3) electrical abnormalities precede detectable structural changes. This information could be valuable in determining family screening protocols.

Imaging of the right heart--CT and CMR

Right ventricular (RV) structure and function is of substantial importance in a broad variety of clinical conditions. Cardiac magnetic resonance (CMR) and computed tomography (CT) each provide three-dimensional RV imaging, high-resolution evaluation of RV structure/anatomy, and accurate functional assessment without geometric assumptions. This is of particular significance for the RV, where complex geometry compromises reliance on indices derived from two-dimensional (2D) imaging planes. CMR flow-based imaging can be applied to right-sided heart valves, enabling evaluation of hemodynamic and valvular dysfunction that may contribute to or result from RV dysfunction. Tissue characterization imaging by both CMR and CT provides valuable complementary assessment of the RV. Changes in myocardial tissue composition provide a mechanistic substrate for RV dysfunction and cardiac arrhythmias. This review provides an overview of RV imaging by both CMR and CT, with focus on assessment of RV structure/function, flow, and tissue characterization. Emerging evidence and established guidelines are discussed in the context of imaging contributions to diagnosis, prognostic risk stratification and disease management of clinical conditions that impact the right ventricle.

Arrhythmogenic right ventricular cardiomyopathy/dysplasia in Saudi Arabia: a single-center experience with long-term follow-up

BACKGROUND AND OBJECTIVES

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a rare genetic disorder that primarily involves the right ventricle (RV). It is characterized by progressive replacement of RV myocardium by fibrofatty tissues. It commonly presents with ventricular tachycardia (VT) of RV origin and may result in RV failure. The aim of this study is to evaluate the clinical characteristics of adult patients with ARVC/D treated at the Heart Centre, King Faisal Specialist Hospital and Research Centre (KFSH&RC), Riyadh, Saudi Arabia.

DESIGN AND SETTINGS

This is a retrospective study of patients with ARVC/D diagnosed and treated at the KFSH&RC Heart Centre in Riyadh.

PATIENTS AND METHODS

Twenty-two cases with ARVC/D with regular follow-up at our Heart Centre from January 2007 to May 2010 were included in this study. The diagnosis of ARVC/D was made according to the revised International Task Force Criteria. The clinical data were collected from patients' charts and electronic medical records.

RESULTS

The majority of patients were males (18; 82%). The diagnosis of ARVC/D was definite in 18 patients (82%), borderline in 2 (9%), and possible in 2 (9%). The mean age at diagnosis was 33.3 years. The follow-up period ranged from 29 to 132 months, with a mean follow-up period of 84 months. Ten patients presented with sustained VT, and 3 were survivors of cardiac arrest. Electrocardiogram abnormalities were present in 16/22 patients (72.7%). Echocardiographic changes meeting major diagnostic criteria were seen in 16 patients (76%). Cardiac magnetic resonance imaging was performed in 11 patients, and showed changes compatible with major diagnostic criteria in 7 patients (64%). Implantable cardioverter defibrillators (ICDs) were implanted in 17 patients; 8 had appropriate ICD shocks and 5 had inappropriate ICD shocks. Antitachycardia pacing was effective in terminating most of the VT/ventricular fibrillation episodes.

CONCLUSION

ARVC/D is a rare but increasingly recognized heart muscle disease seen in Saudi Arabia and other parts of the world. It is associated with a highly nonspecific presentation. VT of RV origin is a common presentation for this disease. Antiarrhythmic medications and ICD implantation are the main management options.

Arrhythmogenic right ventricular cardiomyopathy (ARVC): cardiovascular magnetic resonance update

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is one of the most arrhythmogenic forms of inherited cardiomyopathy and a frequent cause of sudden death in the young. Affected individuals typically present between the second and fourth decade of life with arrhythmias coming from the right ventricle. Pathogenic mutations in genes encoding the cardiac desmosome can be found in approximately 60% of index patients, leading to our current perception of ARVC as a desmosomal disease. Although ARVC is known to preferentially affect the right ventricle, early and/or predominant left ventricular involvement is increasingly recognized. Diagnosis is made by combining multiple sources of diagnostic information as prescribed by the "Task Force" criteria. Recent research suggests that electrical abnormalities precede structural changes in ARVC. Cardiovascular Magnetic Resonance (CMR) is an ideal technique in ARVC workup, as it provides comprehensive information on cardiac morphology, function, and tissue characterization in a single investigation. Prevention of sudden cardiac death using implantable cardioverter-defibrillators is the most important management consideration. This purpose of this paper is to provide an updated review of our understanding of the genetics, diagnosis, current state-of-the-art CMR acquisition and analysis, and management of patients with ARVC.

Effect of the 2010 task force criteria on reclassification of cardiovascular magnetic resonance criteria for arrhythmogenic right ventricular cardiomyopathy

BACKGROUND

We sought to evaluate the effect of application of the revised 2010 Task Force Criteria (TFC) on the prevalence of major and minor Cardiovascular Magnetic Resonance (CMR) criteria for Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) versus application of the original 1994 TFC. We also assessed the utility of MRI to identify alternative diagnoses for patients referred for ARVC evaluation.

METHODS

968 consecutive patients referred to our institution for CMR with clinical suspicion of ARVC from 1995 to 2010, were evaluated for the presence of major and minor CMR criteria per the 1994 and 2010 ARVC TFC. CMR criteria included right ventricle (RV) dilatation, reduced RV ejection fraction, RV aneurysm, or regional RV wall motion abnormalities. When quantitative measures of RV size and function were not available, and in whom abnormal size or function was reported, a repeat quantitative analysis by 2 qualified CMR physicians in consensus.

RESULTS

Of 968 patients, 220 (22.7%) fulfilled either a major or a minor 1994 TFC, and 25 (2.6%) fulfilled any of the 2010 TFC criterion. Among patients meeting any 1994 criteria, only 25 (11.4%) met at least one 2010 criterion. All patients who fulfilled a 2010 criteria also satisfied at least one 1994 criterion. Per the 2010 TFC, 21 (2.2%) patients met major criteria and 4 (0.4%) patients fulfilled at least one minor criterion. Eight patients meeting 1994 minor criteria were reclassified as satisfying 2010 major criteria, while 4 patients fulfilling 1994 major criteria were reclassified to only minor or no criteria under the 2010 TFC.Eighty-nine (9.2%) patients had alternative cardiac diagnoses, including 43 (4.4%) with clinically significant potential ARVC mimics. These included cardiac sarcoidosis, RV volume overload conditions, and other cardiomyopathies.

CONCLUSIONS

Application of the 2010 TFC resulted in reduction of total patients meeting any diagnostic CMR criteria for ARVC from 22.7% to 2.6% versus the 1994 TFC. CMR identified alternative cardiac diagnoses in 9.2% of patients, and 4.4% of the diagnoses were potential mimics of ARVC.

Mutation-positive arrhythmogenic right ventricular dysplasia/cardiomyopathy: the triangle of dysplasia displaced

INTRODUCTION

The traditional description of the Triangle of Dysplasia in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (ARVD/C) predates genetic testing and excludes biventricular phenotypes.

METHODS AND RESULTS

We analyzed Cardiac Magnetic Resonance (CMR) studies of 74 mutation-positive ARVD/C patients for regional abnormalities on a 5-segment RV and 17-segment LV model. The location of electroanatomic endo- and epicardial scar and site of successful VT ablation was recorded in 11 ARVD/C subjects. Among 54/74 (73%) subjects with abnormal CMR, the RV was abnormal in almost all (96%), and 52% had biventricular involvement. Isolated LV abnormalities were uncommon (4%). Dyskinetic basal inferior wall (94%) was the most prevalent RV abnormality, followed by basal anterior wall (87%) dyskinesis. Subepicardial fat infiltration in the posterolateral LV (80%) was the most frequent LV abnormality. Similar to CMR data, voltage maps revealed scar (<0.5 mV) in the RV basal inferior wall (100%), followed by the RV basal anterior wall (64%) and LV posterolateral wall (45%). All 16 RV VTs originated from the basal inferior wall (50%) or basal anterior wall (50%). Of 3 LV VTs, 2 localized to the posterolateral wall. In both modalities, RV apical involvement never occurred in isolation.

CONCLUSION

Mutation-positive ARVD/C exhibits a previously unrecognized characteristic pattern of disease involving the basal inferior and anterior RV, and the posterolateral LV. The RV apex is only involved in advanced ARVD/C, typically as a part of global RV involvement. These results displace the RV apex from the Triangle of Dysplasia, and provide insights into the pathophysiology of ARVD/C.

Incremental value of cardiac magnetic resonance imaging in arrhythmic risk stratification of arrhythmogenic right ventricular dysplasia/cardiomyopathy-associated desmosomal mutation carriers

OBJECTIVES

The aim of this study was to identify the incremental value and optimal role of cardiac magnetic resonance (CMR) imaging in arrhythmic risk stratification of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C)-associated desmosomal mutation carriers without histories of sustained ventricular arrhythmia.

BACKGROUND

Risk stratification of ARVD/C mutation carriers is challenging.

METHODS

Sixty-nine patients (mean age 27.0 ± 15.3 years, 42% men) harboring ARVD/C-associated pathogenic mutations (83% plakophilin 2) without prior sustained ventricular arrhythmias were included. Electrocardiographic and 24-h Holter monitoring findings closest to presentation were analyzed for electrical abnormalities per revised task force criteria. CMR studies were done to identify abnormal cardiac structure and function according to the revised task force criteria.

RESULTS

Overall, 42 patients (61%) presented with electrical abnormalities on the basis of electrocardiography and Holter monitoring, of whom 20 (48%) had abnormal results on CMR. Only 1 of 27 patients (4%) without electrical abnormalities at initial evaluation had abnormal CMR results. Over a mean follow-up period of 5.8 ± 4.4 years, 11 patients (16%) experienced sustained ventricular arrhythmias, exclusively in patients with both electrical abnormalities (electrocardiography and/or Holter monitoring) and abnormal CMR results.

CONCLUSIONS

These results suggest that electrical abnormalities on electrocardiography and Holter monitoring precede detectable structural abnormalities in ARVD/C mutation carriers. Therefore, evaluation of cardiac structure and function using CMR is probably not necessary in the absence of baseline electrical abnormalities. Among ARVD/C mutation carriers, the presence of both electrical and CMR abnormalities identifies patients at high risk for events and thus patients who might benefit from prophylactic implantable cardioverter-defibrillator placement.

Prognostic value of cardiovascular magnetic resonance in patients with suspected arrhythmogenic right ventricular cardiomyopathy

BACKGROUND

Early recognition and accurate risk stratification are important in the management of arrhythmogenic right ventricular cardiomyopathy (ARVC). Identification of predictors of outcome by cardiovascular magnetic resonance (CMR) in patients undergoing evaluation for ARVC is limited. We investigated the predictive value of morphological abnormalities detected by CMR for major clinical events in patients with suspected ARVC.

METHODS

We performed a longitudinal study on 369 consecutive patients with at least one criterion for ARVC. Abnormal CMR was defined by the presence of one of the following: increased right ventricular (RV) volumes, reduced RV ejection fraction, RV regional wall motion abnormalities, myocardial fatty infiltration, and myocardial fibrosis. The end-point was a composite of cardiac death, sustained ventricular tachycardia, ventricular fibrillation, and appropriate ICD discharge.

RESULTS

Twenty patients met the composite end-point over a mean follow-up of 4.3±1.5 years. An abnormal CMR was an independent predictor of outcomes (p<0.001). The presence of multiple abnormalities heralded a particular high risk of events (HR 23.0, 95% CI 5.7-93.2, p<0.001 for 2 abnormalities; HR 35.8, 95% CI 9.7-132.6, p<0.001 for 3 or more abnormalities). The positive predictive value of an abnormal CMR study was 21.0% for an adverse event, whilst the negative predictive value of a normal CMR study was 98.8% over the follow-up period.

CONCLUSIONS

CMR provides important prognostic information in patients under evaluation for ARVC. A normal study portends a good prognosis. Conversely, the presence of multiple abnormalities identifies a high risk group of patients who may benefit from ICD implantation.

Arrhythmogenic right ventricular cardiomyopathy mimics: role of cardiovascular magnetic resonance

BACKGROUND

Cardiovascular magnetic resonance (CMR) is commonly used in patients with suspected arrhythmogenic right ventricular cardiomyopathy (ARVC) based on ECG, echocardiogram and Holter. However, various diseases may present with clinical characteristics resembling ARVC causing diagnostic dilemmas. The aim of this study was to explore the role of CMR in the differential diagnosis of patients with suspected ARVC.

METHODS

657 CMR referrals suspicious for ARVC in a single tertiary referral centre were analysed. Standardized CMR imaging protocols for ARVC were performed. Potential ARVC mimics were grouped into: 1) displacement of the heart, 2) right ventricular overload, and 3) non ARVC-like cardiac scarring. For each, a judgment of clinical impact was made.

RESULTS

Twenty patients (3.0%) fulfilled imaging ARVC criteria. Thirty (4.6%) had a potential ARVC mimic, of which 25 (3.8%) were considered clinically important: cardiac displacement (n=17), RV overload (n=7) and non-ARVC like myocardial scarring (n=4). One patient had two mimics; one patient had dual pathology with important mimic and ARVC. RV overload and scarring conditions were always thought clinically important whilst the importance of cardiac displacement depended on the degree of displacement from severe (partial absence of pericardium) to epiphenomenon (minor kyphoscoliosis).

CONCLUSIONS

Some patients referred for CMR with suspected ARVC fulfil ARVC imaging criteria (3%) but more have otherwise unrecognised diseases (4.6%) mimicking potentially ARVC. Clinical assessment should reflect this, emphasising the assessment and/or exclusion of potential mimics in parallel with the detection of ARVC major and minor criteria.

Utility of cardiovascular magnetic resonance in identifying substrate for malignant ventricular arrhythmias

BACKGROUND

Sudden cardiac death (SCD) and sustained monomorphic ventricular tachycardia (SMVT) are frequently associated with prior or acute myocardial injury. Cardiovascular magnetic resonance (CMR) provides morphological, functional, and tissue characterization in a single setting. We sought to evaluate the diagnostic yield of CMR-based imaging versus non-CMR-based imaging in patients with resuscitated SCD or SMVT.

METHODS AND RESULTS

Eighty-two patients with resuscitated SCD or SMVT underwent routine non-CMR imaging, followed by a CMR protocol with comprehensive tissue characterization. Clinical reports of non-CMR imaging studies were blindly adjudicated and used to assign each patient to 1 of 7 diagnostic categories. CMR imaging was blindly interpreted using a standardized algorithm used to assign a patient diagnosis category in a similar fashion. The diagnostic yield of CMR-based and non-CMR-based imaging, as well as the impact of the former on diagnosis reclassification, was established. Relevant myocardial disease was identified in 51% of patients using non-CMR-based imaging and in 74% using CMR-based imaging (P=0.002). Forty-one patients (50%) were reassigned to a new or alternate diagnosis using CMR-based imaging, including 15 (18%) with unsuspected acute myocardial injury. Twenty patients (24%) had no abnormality by non-CMR imaging but showed clinically relevant myocardial disease by CMR imaging.

CONCLUSIONS

CMR-based imaging provides a robust diagnostic yield in patients presenting with resuscitated SCD or SMVT and incrementally identifies clinically unsuspected acute myocardial injury. When compared with non-CMR-based imaging, a new or alternate myocardial disease process may be identified in half of these patients.

Right ventricular mechanical dispersion is related to malignant arrhythmias: a study of patients with arrhythmogenic right ventricular cardiomyopathy and subclinical right ventricular dysfunction

AIMS

We evaluated if right ventricular (RV) mechanical dispersion by strain was related to ventricular arrhythmias (VT/VF) in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) and if mechanical dispersion was increased in so far asymptomatic mutation carriers.

METHODS AND RESULTS

We included 69 patients, 42 had symptomatic ARVC and 27 were mutation positive asymptomatic family members. Forty healthy individuals served as controls. Myocardial strain was assessed in 6 RV and 16 left ventricular (LV) segments. Contraction duration (CD) in 6 RV and 16 LV segments were measured as the time from onset R on electrocardiogram to maximum myocardial shortening in each segment. The standard deviation of CD was defined as mechanical dispersion. Mechanical dispersion was more pronounced in ARVC patients with arrhythmias compared with asymptomatic mutation carriers and healthy individuals in RV [52(41,63) vs. 35(23,47) vs. 13(9,19)ms, P < 0.001]. Mechanical dispersion was more pronounced in asymptomatic mutation carriers compared with healthy individuals (P < 0.001). Right ventricular mechanical dispersion predicted VT/VF in a multivariate logistic regression analysis [odds ratio (OR), 1.66 (95% confidence interval (CI) 1.06-2.58), P < 0.03]. Right ventricular and LV function by strain were reduced in symptomatic ARVC patients and correlated significantly (R = 0.81, P < 0.001). Right ventricular and LV strain were reduced in asymptomatic mutation carriers compared with healthy individuals (P < 0.001).

CONCLUSION

Right ventricular mechanical dispersion was pronounced in patients with ARVC with VT/VF. Right ventricular mechanical dispersion was present in asymptomatic mutation carriers and may be helpful in risk stratification. Right ventricular and LV function correlated in ARVC patients implying that ARVC is a biventricular disease.

Noninvasive diagnosis of electroanatomic abnormalities in arrhythmogenic right ventricular cardiomyopathy

BACKGROUND

The diagnostic reliability and pathophysiologic relevance of different noninvasive diagnostic criteria for arrhythmogenic right ventricular cardiomyopathy (ARVC) are undefined. We tested the association between noninvasive diagnostic criteria for ARVC and the presence of low-voltage areas (LVAs) detected at electroanatomic voltage mapping (EAM).

METHODS AND RESULTS

Noninvasive diagnostic criteria, including ECG, signal-averaged ECG (SAECG), and cardiac magnetic resonance (CMR) criteria, were compared with the presence and location of LVAs detected at right ventricular (RV) EAM in 17 patients (9 men) aged 50 ± 16 years with biopsy specimen-proven ARVC. LVAs were found in 15 (88%) patients. Patients with surface ECG abnormalities showed a higher degree of RV involvement than those without ECG abnormalities (number of LVAs, 1.8 ± 0.5 versus 0.9 ± 0.6, respectively; P < 0.01). A significant association was found between SAECG abnormalities and LVAs in the RV outflow tract (P = 0.03) but not between SAECG parameters and LVAs in other RV regions. Among CMR findings, RV delayed enhancement was more significantly associated with the distribution of LVAs (free wall, P < 0.01; outflow tract, P < 0.01; posteroinferior wall, P = 0.02). Regional RV dysfunction also showed a good correlation with LVAs, with the most significant association being found with the free wall (P = 0.01), whereas RV fat infiltration at CMR was not correlated with LVAs.

CONCLUSION

In patients with ARVC, SAECG abnormalities correlate with the presence of LVAs selectively in the RV outflow tract, whereas surface ECG abnormalities are associated with a more diffuse RV involvement. Myocardial delayed enhancement is the CMR finding more strongly associated with LVAs, thus supporting the appropriateness of its inclusion among diagnostic criteria for ARVC.

Magnetic resonance imaging assessment of arrhythmogenic right ventricular cardiomyopathy/dysplasia in children

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a genetically determined disease that progresses continuously from conception and throughout life. ARVC/D manifests predominantly in young adulthood. Early identification of the concealed cases in childhood is of utmost importance for the prevention of sudden cardiac death later in life. Magnetic resonance imaging (MRI) is routinely requested in patients with a confirmed or suspected diagnosis of ARVC/D and in family members of the patients with ARVC/D. Although the utility of MRI in the assessment of ARVC/D is well recognized in adults, MRI is a low-yield test in children as the anatomical, histological, and functional changes are frequently subtle or not present in the early phase of the disease. MRI findings of ARVC/D include morphologic changes such as right ventricular dilatation, wall thinning, and aneurismal outpouchings, as well as abnormal tissue characteristics such as myocardial fibrosis and fatty infiltration, and functional abnormalities such as global ventricular dysfunction and regional wall motion abnormalities. Among these findings, regional wall motion abnormalities are the most reliable MRI findings both in children and adults, while myocardial fibrosis and fat infiltration are rarely seen in children. Therefore, an MRI protocol should be tailored according to the patient's age and compliance, as well as the presence of other findings, instead of using the protocol that is used for adults. We propose that MRI in children with ARVC/D should focus on the detection of regional wall motion abnormalities and global ventricular function by using a cine imaging sequence and that the sequences for myocardial fat and late gadolinium enhancement of the myocardium are reserved for those who show abnormal findings at cine imaging. Importantly, MRI should be performed and interpreted by experienced examiners to reduce the number of false positive and false negative readings.

Case Report: Nonarrhythmogenic Right Ventricular Dysplasia Presenting with Severe Right Ventricular Failure in an Adolescent

Right ventricular dysplasia is usually discovered by the presence of ventricular arrhythmia. As arrhythmia is an epiphenomenon, the first presentation of some cases can be primarily heart failure. We describe an adolescent girl who presented with progressive right heart failure and whose hallmark was fibrofatty replacement of ventricular muscle, especially of the right side, without ventricular arrhythmia. The patient was successfully treated by orthotopic heart transplantation.

[Current indications for cardiac MR imaging]

MRI has acquired over the years a role in the evaluation of cardiovascular pathology especially with regards to its ability to assess right and left ventricular function and delayed postcontrast "viability" sequences. Current class I clinical indications include: viability for patients with ischemic cardiomyopathy and acute coronary syndrome, etiology and prognostic evaluation of non-ischemic cardiomyopathies including myocarditis and arrhytmogenic right ventricular cardiomyopathy, chronic pericarditis and cardiac masses, non-urgent aortic aneurysm and dissection, congenital cardiopathies: vascular malformations and follow-up after curative or palliative surgery. MRI provides a complete non operator dependent evaluation, and is particularly useful for follow-up since it may be repeated due to its absence of ionizing radiation

Morphologic variants of familial arrhythmogenic right ventricular dysplasia/cardiomyopathy a genetics-magnetic resonance imaging correlation study

OBJECTIVES

The purpose of this study was to determine the extent of left ventricular (LV) involvement in individuals predisposed to developing arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), and to investigate novel morphologic variants of ARVD/C.

BACKGROUND

The discovery of desmosomal mutations associated with ARVD/C has led researchers to hypothesize equal right ventricular (RV) and LV affliction in the disease process.

METHODS

Thirty-eight (age 30 +/- 17 years; 18 males) family members of 12 desmosomal mutation-carrying ARVD/C probands underwent genotyping and cardiac magnetic resonance imaging (CMR). The CMR investigators were blinded to clinical and genetic data.

RESULTS

Twenty-five individuals had mutations in PKP2, DSP, and/or DSG2 genes. RV abnormalities were associated with the presence of mutation(s) and with disease severity determined by criteria (minor = 1; major = 2) points for ARVD/C diagnosis. The only LV abnormality detected, the presence of intramyocardial fat, was present in 4 individuals. Each of these individuals was a mutation carrier, whereas 1 had no previously described ARVD/C-related abnormality. On detailed CMR, a focal "crinkling" of the RV outflow tract and subtricuspid regions ("accordion sign") was observed in 60% of the mutation carriers and none of the noncarriers (p < 0.001). The sign was present in 0%, 37%, 71%, and 75% of individuals who met 1, 2, 3, and 4+ criteria points, respectively (p < 0.01).

CONCLUSIONS

Despite a possible LV involvement in ARVD/C, the overall LV structure and function are well preserved. Independent LV involvement is of rare occurrence. The accordion sign is a promising tool for early diagnosis of ARVD/C. Its diagnostic utility should be confirmed in larger cohorts.