Diagnostic Differentiation Between Arrhythmogenic Cardiomyopathy and Athlete’s Heart by Using Imaging
Author + information
- Received March 19, 2018
- Revision received April 17, 2018
- Accepted April 19, 2018
- Published online September 3, 2018.
Author Information
- Flavio D’Ascenzi, MD, PhDa,∗ (flavio.dascenzi{at}unisi.it), @FlavioDascenzi,
- Marco Solari, MDa,
- Domenico Corrado, MD, PhDb,
- Alessandro Zorzi, MD, PhDb and
- Sergio Mondillo, MDa
- aDepartment of Medical Biotechnologies, Division of Cardiology, University of Siena, Siena, Italy
- bDepartment of Cardiac, Thoracic, and Vascular Sciences, Division of Cardiology, University of Padova, Padova, Italy
- ↵∗Address for correspondence:
Dr. Flavio D’Ascenzi, Department of Medical Biotechnologies, Division of Cardiology, University of Siena, Viale M. Bracci, 16 53100 Siena, Italy.
Central Illustration
Abstract
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.
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a rare genetic disease histologically characterized by replacement of myocardium with fibrous and fatty tissue, resulting in right ventricular (RV) dilation, dysfunction, and ventricular arrhythmia (1). ARVC is an important cause of sudden cardiac death (SCD) in youth and athletes (2). Life-threatening ventricular arrhythmias may occur in previously asymptomatic individuals and are typically caused by physical exercise (3).
Diagnosis of ARVC is based on International Task Force Criteria, which combine family history and electrophysiological, morphological, functional, and histological criteria (4). In 2010, Task Force Criteria were modified to improve sensitivity while maintaining specificity, mostly for the clinical screening of family members, by incorporating the recent advances in genetic testing and by providing quantitative imaging parameters, also by cardiac magnetic resonance (CMR) imaging (5). In clinical practice, CMR has become the preferred imaging technique for evaluating the RV when ARVC is suspected because it is more sensitive than echocardiography for detecting early ventricular dilation and dysfunction when clinical manifestations of early ARVC are subtle (6). An additional advantage of CMR is its ability to characterize tissue types. Although CMR is a highly accurate imaging modality, it is expensive, not widely available, and time consuming, and claustrophobic patients may be unable to undergo the examination. Hence, echocardiography still has a crucial role in detecting RV abnormalities and particularly valuable for the high quality of acoustic windows usually found in young subjects; however, expertise and a focused examination are required (7).
According to the Task Force Criteria, diagnosis of ARVC by echocardiography requires a combination of regional RV wall motion abnormalities (WMAs) and global RV dilation and dysfunction. Cutoff values were derived from studies in the general population. Recently, a number of studies focused on training-induced RV remodeling and revealed that some features of the so-called “athlete’s heart” may overlap with those of ARVC, especially at an early stage of the disease. Therefore, a careful evaluation of the RV is required for differential diagnosis in order to avoid false diagnosis of ARVC (by interpreting physiological features as abnormal) or, on the contrary, to fail to identify pathological features of a disease at risk of sports-related SCD (8).
This paper provides a thorough discussion of the echocardiographic characteristics of RV remodeling in athletes, with a specific focus on the differential diagnosis between athlete’s heart and ARVC.
Athlete’s Heart
Intensive training results in morphological and functional remodeling of cardiac chambers and in peripheral cardiovascular adaptations.
Cardiac enlargement was demonstrated by thoracic percussion in cross-country skiers and confirmed by chest radiograms, pathology reports (9), and in the 1970s, by electrocardiography (ECG) and vectorcardiography (10). Two-dimensional echocardiography has led to important advances in our understanding of cardiac adaptation to exercise conditioning (11–16). Although athletic training results in remodeling of all cardiac cavities, formal assessment of the RV has often been neglected primarily because of the lack of simple and reliable methods to estimate RV function (17) and its complex geometry (18). However, in the last decade, several studies have investigated RV remodeling in athletes and have described the most relevant characteristics of RV adaptation to training. The most important findings are summarized in Table 1.
Summary of the Most Relevant Echocardiographic Findings of the Right Ventricle in Athlete’s Heart
RV size
Current evidence suggests that intensive and prolonged physical exercise induces an increase in RV cavity size and RV mass (19–21) and that competitive athletes exhibit a dimensional increase in the right chambers (7,21,22). RV size can be estimated by echocardiography through RV outflow tract (RVOT) diameters, RV end-diastolic and end-systolic areas, and RV basal and mid-cavity diameters, as shown in Figure 1. Echocardiographic studies have demonstrated that the increase in RV size is more evident in male endurance athletes, in whom differential diagnosis with pathological remodeling of ARVC may be particularly challenging, although athletes usually maintain normal RV systolic and diastolic function, end-diastolic wall thickness, normal collapsibility of inferior vena cava, and normal pulmonary artery systolic pressure (23). The extent of RV remodeling results in a relevant percentage of athletes fulfilling dimensional echocardiographic criteria for the diagnosis of ARVC. Zaidi et al. (23) found that 61% of male and 46% of female athletes had RV dimensions above the cutoff value of the minor criteria, whereas 37% of male and 24% of female athletes had RV dimensions above the cutoff value of the major criteria. In a population of Olympic athletes, 23% exceeded the criteria of RV dilation proposed by the American Society of Echocardiography, and in 16% and 41% of cases, respectively, fulfilled major and minor criteria for the diagnosis of ARVC (24). Endurance athletes demonstrated the greatest degree of RV remodeling and the highest percentages of RV classified as “dilated” according to the American Society of Echocardiography and Task Force Criteria for ARVC (24). Notably, RVOT dimensions indexed to body surface area (BSA) were greater in female than in male athletes (23,24).
Assessment of RV Size by Echocardiography
RV outflow tract diameters can be obtained by PLAX and PSAX views, whereas RV basal and mid-cavity diameters can be obtained from the 4-chamber view. PLAX = parasternal long-axis; PSAX = parasternal short-axis; RV = right ventricular.
A recent meta-analysis of 46 echocardiographic studies and a total of 6,806 competitive athletes (25) demonstrated that male competitive athletes exhibit a marked RV remodeling in which the upper limits of normality are greater than those in the general population. Athletes engaged in combined sports (such as rowing or canoeing), requiring a combination of static and dynamic exercise, exhibit the greatest RV dimensional remodeling, whereas athletes engaged in strength sports, such as weight lifting, exhibited the lowest degree of RV remodeling.
In addition to the type of sport practiced, increasing age and years of training also have been identified as predictors of right heart dimensions (26); thus, athletes with more years of training show the greatest degree of RV remodeling.
Cardiovascular remodeling induced by exercise is associated not only with cardiac but also with extracardiac modifications (27,28), including dilation of the inferior vena cava that represents the consequence of physiological adaptation to the augmented venous return, increased volume load, and cardiac output (29,30). Therefore, a comprehensive evaluation of athlete’s heart should include evaluation of extracardiac adaptations induced by hemodynamic changes imposed by training.
Exercise-induced RV remodeling is dynamic in nature. Indeed, when evaluating the athlete during the competitive season, an increase in RV size can be found in comparison with baseline data, confirming that RV remodeling is a dynamic process and that the RV rapidly adapts in response to the increased demand imposed by training (31). These findings also were confirmed in children practicing competitive sports (32) and suggest that, although RV dilation in ARVC patients is almost an irreversible process, the extent of training-induced RV enlargement in athlete’s heart can change according to load conditions imposed by training. Furthermore, the anatomic features of the RV, such as a thin wall and a propensity for a volume-overload adaptation, could be responsible for an earlier adaptation of this ventricle compared to that of the left ventricle.
Therefore, taken together, these studies suggest that the RV is often dilated in competitive and top-level athletes. Male sex, sports discipline, age, and years of training should be taken into account in order to properly interpret RV remodeling. The greater the duration and intensity of exercise, the higher the cardiac output and, ultimately, the hemodynamic stimulus for the dimensional increase of the RV (24).
RV morphologic features
Echocardiographic characteristics of RV in athletes are not confined to a mere increase in cavity size. Indeed, elite athletes were found to have a characteristic remodeling of the RV in terms of qualitative features. Up to 81% of elite athletes showed a round-shaped apex, 37% exhibited prominent RV trabeculations, and a hyper-reflective moderator band was found in 0.5% of athletes (24). Conversely, none of the athletes showed the RV WMAs that are required for imaging diagnosis of ARVC in addition to RV dilation. These peculiarities should be carefully taken into account when evaluating the RV of competitive athletes and should be interpreted as a benign and physiological adaptation of the RV induced by the high hemodynamic overload during chronic intensive exercise.
RV function in the athlete
Conventional indexes of RV function
A comprehensive and appropriate assessment of the RV includes the most common indexes of ventricular function, including tricuspid annular plane systolic excursion, tissue Doppler-derived RV peak systolic velocity (RV s′), and early myocardial relaxation velocity (RV e′), RV fractional area change (RVFAC), and RV strain (Figure 2). However, data currently available for RV function in athletes are controversial, and these discrepancies are due mainly to differences among the studies in terms of demographic and athletic characteristics of the study populations and in terms of indexes used for assessing RV function.
Assessment of RV Function by 2D and Speckle-Tracking Echocardiography
Figure shows RV strain, s′ velocity, and TAPSE as measures of RV function. TAPSE = tricuspid annular plane systolic excursion; other abbreviations as in Figure 1.
Despite a marked RV dimensional remodeling, competitive athletes usually have almost normal systolic and normal or supranormal diastolic functions (23,24,33). A recent meta-analysis of 6,806 competitive athletes (25) showed that competitive athletes had a lower reference value of RVFAC (i.e., 32%) than that recommended for the general population by the American Society of Echocardiography (ASE) and the European Association of Cardiovascular Imaging (34) and significantly below the cutoff proposed by the Task Force for ARVC diagnosis, which considers an RVFAC ≥40% to be normal (5). Conversely, normative reference values for tricuspid annular plane systolic excursion, TDI-derived parameters, and RV strain obtained in athletes were comparable with those recommended for the general population, suggesting that the novel echocardiographic techniques seem to assess more accurately RV function in competitive athletes.
Evaluation of RV function by speckle-tracking echocardiography
Application of speckle-tracking echocardiography (STE) has led to a more comprehensive knowledge of exercise-induced cardiac remodeling (16,35). STE has recently been applied extensively to athlete’s heart. Application of STE to the RV provides global RV strain and regional strain values of basal, mid, and apical segments. Although some authors have focused on differences between absolute values of RV and left ventricular (LV) strain between athletes and controls (36), others have analyzed predictors of RV size and strain in athletes (37).
Conflicting results have been reported when applying STE to the RV of athletes. Indeed, although some authors reported normal or even supranormal values of RV global strain in athletes, others found a reduction in athletes compared to controls (22,31,37,38). However, the reduction of RV strain was confined to the basal segment alone, and further studies demonstrated that resting parameters of RV function were poorly suggestive of contractile reserve and, especially in endurance athletes, should not be interpreted as a sign of subclinical damage but rather as a physiological exercise-induced modification (39). Particularly for the basal segment, the hypothesis is that, given that volume is greatest at the RV base, a lesser degree of deformation may be required to generate the same stroke volume, thereby explaining why RV deformation may be reduced in this region (16,39). In subsets of endurance and ultraendurance (25) athletes, a possible detrimental effect of intensive training on the RV systolic function has been hypothesized as RV dysfunction and has been observed to be reduced after ultraendurance competition (37). This marked impact of a single endurance event on RV could represent a sort of “fatigue” that is recovered in most well-trained subjects but that could have detrimental effects in other athletes who are not well adapted. Future studies with large samples of athletes observed over a long-term period are needed to investigate the cumulative effect of chronic exercise on RV function and to interpret the clinical meaning of a transient decrease in RV function.
Taken together, the results of these studies suggest that healthy athletes can show a slightly lower RVFAC at rest and question the applicability of the RVFAC cutoff values included in the Task Force Criteria for differential diagnosis between ARVC and athlete’s heart. On the other hand, the other indexes of RV function are normal in competitive athletes, suggesting that evaluation of RV function should be comprehensive and multiparametric.
Arrhythmogenic RV cardiomyopathy
Pathogenesis and clinical presentation
ARVC is caused by a genetically determined defect of the intercellular junctions called “desmosomes.” The disease is characterized by incomplete penetrance and variable phenotypic expression: it shows a male predominance and typically becomes overt after pubertal development. A family history of SCD or ARVC is reported by ≈50% of patients (40).
The pathophysiological process begins with rupture of the defective desmosomes and consequent necrosis or apoptosis of myocytes that are replaced by fibrofatty tissue. The disease initially affects the subepicardial layers of the ventricular wall and only later becomes transmural. Moreover, the fibrofatty replacement process does not homogenously affect the entire heart but, in the classic (right-dominant) variant, predominantly involves the angles of the so-called triangle of dysplasia (RV inflow, apex, and RVOT). Other variants are characterized by a biventricular or left-dominant involvement (1).
The most common clinical presentation of ARVC is ventricular arrhythmia, which can range from simple premature ventricular beats to ventricular tachycardia and ventricular fibrillation leading to cardiac arrest and SCD (41). The pathogenesis of ventricular arrhythmias changes during the different disease phases: in young, often previously asymptomatic patients, SCD is mainly due to ventricular fibrillation, in the context of bouts of acute myocyte death and reactive inflammation (so-called hot phase). By contrast, older patients with a long-lasting disease more often experience scar-related hemodynamically stable ventricular tachycardia due to a re-entry mechanism around a myocardial scar (42). Heart failure due to RV or biventricular dysfunction (resembling a dilated cardiomyopathy) is rare and observed only in the late stage of the disease.
Typical electrocardiographic abnormalities consisting of T-wave inversion in the right precordial leads V1 to V4 with no J point and ST-segment elevation, and depolarization abnormalities (intraventricular conduction delay, epsilon waves) are observed in most patients (5).
Imaging features and diagnostic criteria
The imaging features of arrhythmogenic cardiomyopathy reflect the regional involvement of the disease process. An essential element for the diagnosis of ARVC by imaging modalities is the presence of a regional RV WMAs, consisting of akinesia and dyskinesia or aneurysm in combination with global RV dilation or dysfunction. However, it must be emphasized that imaging abnormalities are not sufficient for the diagnosis of ARVC, which requires a combination of multiple criteria from different categories (imaging features, ECG abnormalities, ventricular arrhythmia, family history and genetic background, and endomyocardial biopsy) (Table 2) (5).
Criteria for the Diagnosis of Arrhythmogenic Right Ventricular Cardiomyopathy According to the Task Force Criteria
Because the disease process spares the subendocardial layers, which mostly contribute to myocardial contraction, the left ventricle exhibits no dilation and no or mild regional dysfunction. However, in up to 70% of patients, contrast-enhanced CMR reveals areas of fibrofatty replacement in the form of late gadolinium enhancement (LGE), typically confined to the lateral LV wall (43). This observation suggests that the disease process is usually biventricular, although LV involvement often remains clinically concealed.
Link between ARVC and sports activity
Arrhythmogenic cardiomyopathy is one of the leading causes of SCD in athletes (3,44). Competitive sports activity poses a 5-fold increase in the risk of SCD in adolescents and young adults with ARVC (45). Athletic activity also favors ARVC progression and worsening of the diseased arrhythmic substrate because of increased mechanical wall stress and adrenergic stimulation (3,46,47). Clinical studies demonstrated that endurance sports and intense physical exercise increase age-related penetrance, risk of ventricular tachyarrhythmia, and occurrence of heart failure in carriers of the ARVC desmosomal gene (48–50). Indeed, Saberniak et al. (49) found that ARVC patients and mutation-positive family members who regularly practiced sports activity showed reduced biventricular function compared with nonathletes. The amount and intensity of exercise activity were associated with impaired LV and RV functions, and the authors concluded that exercise may aggravate and accelerate myocardial dysfunction in ARVC. These findings are in agreement with those of the study by James et al. (48) in which carriers of the ARVC desmosomal mutation demonstrated that endurance exercise increased the risk of major ventricular arrhythmias, heart failure, and ARVC phenotypic expression in desmosomal mutation carriers. For this reason, current recommendations agree that patients with ARVC should be restricted from competitive sports activity (51,52).
The left-dominant variant of ARVC is characterized by an early and predominant LV involvement (53). At variance with the classic right-dominant variant, the accuracy of conventional investigations, including routine ECG and standard echocardiography for the diagnosis of left-dominant ARVC, is limited because repolarization abnormalities and LV systolic dysfunction, either regional or global, are observed in few affected patients, and the disease lesion can be identified only by using contrast-enhanced CMR imaging (54). Not surprisingly the left-dominant variant is increasingly observed in athletes who have experienced cardiac arrest (55–57).
Differential Diagnosis Between Athlete’s Heart and ARVC
Exercise-induced increase in RV dimension could mimic the RV pathological remodeling in ARVC. Indeed, RV dilation is one of the most relevant phenotypic expression of ARVC (5). Therefore, the differential diagnosis is sometimes challenging in the athlete and could lead to an incorrect diagnosis of a rare and life-threatening disease in healthy subjects, with psychological, economic, and familiar consequences, or to miss a diagnosis in athletes, exposing them to the risk of SCD, particularly during competition. Furthermore, athletic activity may favor the disease expression in carriers of the desmosomal gene mutation and worsen the disease severity in ARVC patients (48,49).
Many efforts have been made in the last decades to solve the controversial issue of the differential diagnosis between athlete’s heart and ARVC and the Task Force Criteria were modified in 2010 to improve the sensitivity while maintaining specificity (5). Despite the undisputed usefulness of the Task Force 2010 criteria as a diagnostic tool for ARVC, concerns have been raised about their practical applicability as a screening tool in low-risk populations (25,58), particularly using imaging modalities.
The imaging criteria proposed by the Task Force rely on a combination of regional RV kinetic abnormalities (i.e., akinesia, dyskinesia, aneurysms or dyssynchronous contraction), and RV dilation or reduced global RV function. Unfortunately, competitive athletes often exhibit training-induced RV dilation and sometimes a slight reduction in RV function. However, despite similarities between athlete’s heart and ARVC, in the last decades, some echocardiographic features have been identified in order to help physicians distinguish between physiological and pathological RV remodeling. These features are summarized in Table 3.
Dimensional and Functional Parameters Obtained by Echocardiography in Arrhythmogenic Right Ventricular Cardiomyopathy Versus Athlete’s Heart
The first relevant echocardiographic difference between ARVC patients and competitive athletes is the presence of RV WMAs: indeed, although RV bulging, dyskinesia, akinesia, and aneurysms are typical findings of ARVC, they are not found in healthy athletes (23,58) (Figures 3A and 3B, Online Videos 1 and 2). Notably, hypokinesia is not considered among the criteria for the diagnosis of ARVC. Recognition of RV regional WMAs needs specific skills in echocardiography, with the possibility of misleading interpretations also in specialized centers. Moreover, standard echocardiographic views do not explore the inferior (subtricuspid) RV wall, which requires a dedicated (inflow) echocardiographic view (Online Video 3). Accordingly, when the echocardiographic examination raises the suspicion of RV WMAs, CMR is needed to confirm the presence of WMAs (Online Video 4).
Typical Features of RV Size and Function in Athlete's Heart and in ARVC
(A) Typical features of athlete's heart. (B) Typical features of ARVC. The arrows indicate wall motion abnormalities, typically found in ARVC. ARVC= arrhythmogenic right ventricular cardiomyopathy; RV = right ventricular; RVOT = right ventricular outflow tract; WMA = wall motion abnormalities; other abbreviations as in Figure 1. See Online Videos 1, 2, 3, and 4.
Apical four-chamber view showing right ventricular wall motion abnormalities in a patient with arrhythmogenic right ventricular cardiomyopathy.
Apical four-chamber view showing a dilated but normocinetic right ventricle of a professional athlete.
Modified parasternal long-axis view focused on the evaluation of right ventricular wall motion.
A case of a female athlete with family history of sudden cardiac death and initial abnormalities identified at the initial clinical and echocardiographic evaluation. Cardiac magnetic resonance confirmed the presence of a cardiomyopathy.
Notably, although RV remodeling in athletes is characterized by a global enlargement of the cardiac chambers, RV dilation is more pronounced in RV inflow than in RVOT (58). Bauce et al. (7), investigating 40 patients with ARVC, 40 athletes, and 40 sedentary control subjects demonstrated that ARVC patients without severe RV dilation or dysfunction had both RV inflow and outflow tract dilation, whereas athletes showed a characteristic dilation of the RV inflow and subpulmonary diameter: RVOT parasternal long-axis diameter was greater in ARVC patients than in athletes, whereas the latter had greater RVOT parasternal long-axis diameter than control subjects. Accordingly, evaluation of RVOT parasternal long-axis diameter could be important for the differential diagnosis. A longitudinal study confirmed these findings, demonstrating that during the competitive season, RV areas and diameters increased whereas RVOTs did not change significantly (31). However, despite the predominant increase in RV body, physicians should be aware that competitive athletes have RVOT diameters beyond the cutoff values suggested by the ASE for the general population (26) and, in some cases, also beyond the thresholds suggested as minor or major criteria for the diagnosis of ARVC (23–25).
RV enlargement in athletes is usually accompanied by a concomitant remodeling of the LV, reflecting a global and symmetrical adaptation of the heart to the hemodynamic changes induced by training (58). This balanced biventricular adaptation does not differ among athletes practicing different sports (24), whereas ARVC patients usually show no or mild LV dilation (7). Recently, the RV/LV ratio <0.9 has been proposed to distinguish between RV physiological remodeling and ARVC (59). In a large population of highly trained athletes, the authors found an RV/LV ratio of 0.74 ± 0.08 (95% confidence interval: 0.73 to 0.75), suggesting that this parameter could be used to properly interpret RV enlargement in borderline cases (24). A similar ratio between RV end-diastolic volume and LV end-diastolic volume of >1.2 on CMR has been reported (59).
The analysis of global RV function is crucial for the differential diagnosis between ARVC and athlete’s heart. Among the Task Force Criteria for ARVC, only RVFAC is taken into account for estimating RV function (5). Although a marked decrease of RVFAC is uncommon in healthy athletes, a slight reduction of RVFAC can be found (25). Therefore, physicians should be aware that RVFAC is sometimes reduced also in healthy athletes. Furthermore, the calculation of RVFAC has some relevant limitations, such as reproducibility. Recently an expert consensus document from the European Association of Cardiovascular Imaging discussing ARVC has recommended the inclusion of additional quantitative echocardiographic data, suggesting that a careful assessment of RV function will improve the accuracy of ARVC diagnosis (58) and support the use of additional parameters for determining RV function in these subjects (22,25,37,60). Indeed, global RV strain is typically reduced in ARVC patients, whereas it is normal in athletes (Figures 3A and 3B). ARVC patients may show a subclinical RV dysfunction with reduced RV global longitudinal strain, and a further decrease is observed in ARVC patients who are regularly engaged in sports activities (49). Additionally, mechanical dispersion of RV contraction detected by STE may represent an early predictor of future arrhythmic events (61,62).
Additional Role of CMR
CMR has emerged as a second-line technique for the differential diagnosis between athlete’s heart and ARVC and currently plays a relevant role in helping to establish an accurate diagnosis in athletes (63). Indications for the use of CMR include confirmation of abnormal or borderline echocardiographic findings or when a left-dominant arrhythmogenic cardiomyopathy is suspected (apparently unexplained T-wave inversion in the inferolateral leads and/or ventricular arrhythmia with a right bundle branch block configuration suggesting LV origin) (64). Due to the high spatial resolution and unlimited imaging planes, CMR offers the potential to optimally evaluate dilation and dysfunction, regional WMAs, and structural changes of the RV (64). It must be emphasized that areas of apparent dyskinesia and bulging are frequently encountered in normal individuals and that a combination of WMAs and global RV dilation and dysfunction is needed to fulfill the CMR criteria for ARVC diagnosis (5,65). The ability of CMR to allow noninvasive tissue characterization by using dedicated sequences for evaluation of fat infiltration and post-contrast sequences for LGE is another important advantage of CMR. Although tissue characterization of the RV is not included among current diagnostic criteria, the presence of fat infiltration and/or LGE in an athlete with RV morphological and functional abnormalities may be useful to confirm the diagnosis (58). However, there are some possible pitfalls that should be taken into account. The first pitfall is that spin-echo sequences, which are used to detect the fatty tissue, may lead to ARVC misdiagnosis based on the low specificity of increased intramyocardial fat (66,67). The second pitfall is that it is conventionally considered problematic to detect LGE at the level of the thin RV wall (43). Availability of the newer generation CMR machines with updated pulse sequences enhance the ability to identify RV intramyocardial fibrofatty scar tissue and to discriminate pathologic fatty infiltration from normal epicardial fat (64). Recent studies demonstrated the usefulness of combined regional wall motion assessment and tissue characterization by CE-CMR. The highest accuracy was found when WMAs and pre- and post-contrast signal abnormalities were considered together (68).
Left ventricular LGE with a nonischemic distribution is observed in most ARVC patients and is more reproducible. In patients with left-dominant ARVC, it can represent the only abnormality at cardiac imaging. However, this finding is conventionally believed to lack specificity in the setting of differential diagnosis with the athlete’s heart because of the high prevalence of LV LGE in trained individuals (54). To overcome this possible limitation, it is crucial to evaluate the pattern and regional distribution of LGE: in athletes, it is usually confined to the junction between the free wall and septum, probably as a result of increased pulmonary pressure during exercise, whereas in ARVC patients, a stria of LGE with a nonischemic (i.e., subepicardial/midmyocardial) distribution mostly involving the inferolateral LV wall is typically observed.
Beyond Cardiac Imaging: A Comprehensive Approach
The differential diagnosis between ARVC and athlete’s heart based only on cardiac imaging may be difficult, and second-line investigation such as CMR can provide equivocal findings. However, it is important to stress that ARVC is characterized by multiple abnormalities including not only ventricular dilation and dysfunction but also ECG changes and ventricular arrhythmia. Moreover, as the disease is genetically determined, a large proportion of patients exhibit a positive family history for ARVC or SCD. Accordingly, a comprehensive clinical approach that includes ECG, ambulatory ECG monitoring, stress testing, and evaluation of family members may be useful to refine the diagnosis (Central Illustration).
How to Distinguish Between Athlete's Heart and Arrhythmogenic Cardiomyopathy
The differential diagnosis between athlete's heart and arrhythmogenic right ventricular cardiomyopathy include imaging features and comprehensive clinical approaches including ECG, ambulatory ECG monitoring, stress testing, and evaluation of family members. CMR = cardiac magnetic resonance; ECG = electrocardiography; LGE = late gadolinium enhancement; LV = left ventricular; RV = right ventricular; RVOT = right ventricular outflow tract; WMA = wall motion abnormality.
Conclusions
The differential diagnosis between athlete’s heart and ARVC is often challenging. Echocardiography is the first imaging technique used in this setting, and a comprehensive echocardiographic assessment of RV morphology and function could provide relevant information for the differential diagnosis between athlete’s heart and ARVC and to properly guide the indication to CMR. Although imaging techniques could help distinguish between physiological and pathological RV remodeling, integrating these findings with ECG, clinical signs and symptoms, family history, and occurrence of arrhythmia is crucial, particularly in borderline cases.
Footnotes
All authors have reported that they have no industrial relationships relevant to the contents of this paper to disclose.
- Abbreviation and Acronyms
- ARVC
- arrhythmogenic right ventricular cardiomyopathy
- CMR
- cardiac magnetic resonance
- LGE
- late gadolinium enhancement
- LV
- left ventricular
- RV
- right ventricular
- RVFAC
- right ventricular fractional area change
- RVOT
- right ventricular outflow tract
- SCD
- sudden cardiac death
- STE
- speckle-tracking echocardiography
- WMA
- wall motion abnormality
- Received March 19, 2018.
- Revision received April 17, 2018.
- Accepted April 19, 2018.
- 2018 American College of Cardiology Foundation
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- Barison A.,
- Todiere G.,
- et al.