Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)

ARVC occupies a genuinely distinctive place in this section: it’s the cardiomyopathy phenotype built specifically around the right ventricle, in a section otherwise dominated by LV-centered disease — and it’s a leading cause of sudden cardiac death in young people and athletes, which raises the stakes on getting the diagnosis right. See Introduction to Diseases of the Myocardium for how ARVC fits into the broader phenotype framework this page builds on.

What ARVC Is

ARVC is an inherited disorder causing fibrofatty replacement of the RV myocardium, producing RV dilation and dysfunction, myocardial scarring, and a real risk of sudden cardiac death from ventricular arrhythmia. It usually manifests in the second to fourth decade of life, affects men more frequently than women, and shows age-related penetrance with substantial clinical and genetic variability even within the same family.

Genetics

Most ARVC follows autosomal dominant inheritance with variable penetrance, caused by mutations in genes encoding desmosomal proteins — plakophilin-2 (PKP2), desmoplakin (DSP), desmoglein-2 (DSG2), desmocollin-2 (DSC2), and plakoglobin (JUP) — which together account for about half of disease. Non-desmosomal genes are also implicated: transmembrane protein 43 (TMEM43), lamin A/C, titin (TTN), desmin, alpha-T-catenin (CTNNA3), N-cadherin, and phospholamban. Rare recessive forms — Carvajal syndrome and Naxos disease — present with a distinctive cutaneous phenotype alongside the cardiac findings. Genotype carries real prognostic weight: patients with multiple variants tend to develop a more severe phenotype, and DSP or DSG2 variant carriers are specifically more prone to heart failure.

Pathology: The Triangle, Now a Quadrangle, of Dysplasia

Histologically, ARVC is characterized by fibrofatty replacement occurring in an epicardial-to-endocardial direction, classically concentrated in three regions collectively termed the “triangle of dysplasia”: the RV apex, the subpulmonic (outflow tract) anterior wall, and the inferoposterior (inflow tract) wall.

This concept has been meaningfully revised. Autopsy data show LV histopathologic involvement is genuinely common — in one UK series of patients who died suddenly from ARVC, 87% had LV involvement on postmortem examination — with the inferolateral LV wall the most frequently affected territory. This has led to the “quadrangle of dysplasia” concept, adding the LV inferolateral wall to the original three RV regions, and to proposals from some authors to rename the disease “arrhythmogenic cardiomyopathy” altogether, dropping the right-ventricular specification. Recognizing this biventricular reality matters practically: it broadens the scope of functional assessment in suspected ARVC, and it reduces the real risk of misclassifying biventricular ARVC as dilated cardiomyopathy instead — and when LV involvement predominates without the RV findings that define ARVC itself, the current diagnostic framework instead classifies the patient under non-dilated left ventricular cardiomyopathy, reflecting genuine genetic overlap between the two phenotypes.

Clinical Presentation

ARVC should be suspected in adolescents or young adults presenting with palpitations, syncope, or aborted sudden death. Frequent ventricular ectopy or ventricular tachycardia of LBBB morphology is among the most common presentations, and right precordial T-wave inversion (V1–V3) on a routine ECG should itself raise suspicion. Less common ECG findings include low QRS voltage in the peripheral leads and terminal activation delay in the right precordial leads. RV dilation found incidentally on 2D echocardiography is itself a frequent reason patients are first referred for further evaluation.

A genuine diagnostic trap worth knowing: chest pain, dynamic ST-T wave changes, and myocardial enzyme release in the setting of normal coronary arteries can occur in ARVC — a presentation that mimics myocarditis or acute MI, and requires the differential to be actively considered rather than assumed away by normal coronaries. Less commonly, ARVC presents as RV or biventricular heart failure that can mimic DCM or non-dilated LV cardiomyopathy directly — reinforcing why a thorough assessment of both ventricles matters even when the presentation doesn’t look classically RV-predominant.

Epsilon waves and signal-averaged ECG (SAECG) deserve a specific caution: these have been part of classic ARVC teaching, but are frequently over-diagnosed, show poor inter-observer agreement even among experts, and can occur in the setting of severe structural disease without adding meaningfully to the diagnosis. Use them with caution rather than as a primary diagnostic anchor.

Why Conventional RV Function Parameters Underperform Here

TAPSE and RV tissue Doppler S′ — the standard quick measures of RV systolic function — typically become abnormal only in advanced ARVC. They’re also limited by angle dependency relative to the plane of longitudinal contraction, a problem that worsens specifically in ARVC as tricuspid annular dilation — which also drives secondary tricuspid regurgitation as the disease progresses — and displacement alter that plane later in the disease course. See Evaluation of the Right Ventricle for the general approach these parameters fit into — and why, in ARVC specifically, they shouldn’t be relied upon as early or standalone indicators.

The 2010 Revised Task Force Criteria: Real Numbers, Not Just Qualitative Impressions

This is the central diagnostic framework for ARVC, and it’s worth knowing the actual thresholds rather than a vague sense of “RV looks dilated and dysfunctional.”

	Major criterion	Minor criterion
Wall motion	Regional RV akinesia, dyskinesia, or aneurysm	Regional RV akinesia or dyskinesia
PLAX RVOT diameter	≥32 mm (≥19 mm/m²)	29–32 mm
PSAX RVOT diameter	≥36 mm (≥21 mm/m²)	32–36 mm
RV fractional area change	≤33%	33–40%

A major criterion requires the wall motion abnormality plus at least one of the structural/functional findings at major threshold; the minor tier works the same way at its own thresholds. Each parameter carries real, quantified diagnostic accuracy, worth knowing rather than treating all three as interchangeable:

• PLAX RVOT ≥32 mm: 75% sensitive, 95% specific
• PSAX RVOT ≥36 mm: 62% sensitive, 95% specific
• FAC ≤33% with a regional wall motion abnormality: 55% sensitive, 95% specific

RVOT dilation is seen in essentially all ARVC patients — 100% of probands in the North American Multidisciplinary Study had RVOT dilation — making it one of the most reliably present structural findings, even though its specificity alone (without the accompanying wall motion abnormality) is limited. Measure the RVOT in both PLAX and PSAX views, since the PLAX view in particular is highly dependent on transducer angle and rib interspace, and shouldn’t be used as the sole view for RVOT assessment.

RV Systolic Function and Fractional Area Change

Qualitative RV systolic dysfunction — global or regional — is common, present in 79% of probands in the North American Multidisciplinary Study, with the anterior wall and apex most frequently affected. RV fractional area change (FAC) from the apical four-chamber view is the most useful conventional quantitative correlate of RV systolic function in ARVC, calculated as (end-diastolic area − end-systolic area) ÷ end-diastolic area. Beyond its diagnostic role in the Task Force Criteria, FAC also carries independent prognostic value, predicting major adverse cardiac events in this population — worth quantifying whenever feasible, even when endocardial definition is imperfect, given this dual diagnostic-and-prognostic importance. An ultrasound-enhancing agent can help when endocardial delineation is poor.

Structural Features Worth Screening For Specifically

Beyond chamber size and function, several structural findings occur with increased frequency in ARVC and carry real diagnostic weight:

• Trabecular derangement — the single most frequent structural abnormality in the North American Multidisciplinary Study, present in 54% of probands versus none of matched controls.
• A hyperreflective (hyperechoic) moderator band.
• Focal RV wall thinning, distinct from the akinetic/dyskinetic segments described above.
• Localized aneurysms or sacculations, particularly at the RV inflow tract, apex, and infundibulum — the same regions emphasized by the triangle of dysplasia.

Strain Imaging: Earlier Detection, Genuine Promise

RV longitudinal strain abnormalities occur before overt RV dysfunction develops, making strain quantification a genuinely promising tool for screening relatives or genotype-positive individuals who don’t yet meet full Task Force Criteria.

• Normal RV longitudinal strain, using a six-segment model (apical, basal, and mid free wall and septum), is more negative than −20% in healthy adults; a cutoff of −18% has been shown to differentiate normal from abnormal segments in ARVC.
• Mechanical dispersion — the variability (typically expressed as standard deviation) in time-to-peak systolic strain across RV segments — carries both diagnostic and prognostic value, and has been specifically correlated with malignant arrhythmia risk in established disease.
• The subtricuspid RV basal region is a specific site worth examining deliberately, since mechanical dysfunction there has been emphasized in both established and preclinical stages of ARVC.
• A technical note: prominent trabeculations should be excluded from strain analysis, with tracking focused on genuine endocardial contraction rather than trabecular motion.
• The optimal strain metric (free-wall strain, global longitudinal strain, or segmental strain) hasn’t yet been definitively established — all have shown value, but consensus on which is best hasn’t been reached.

3D Echocardiography

3D imaging can reduce RV volume measurement variability compared with 2D, and avoids some of 2D’s planar limitations for an inherently complex, asymmetric chamber — though it remains technically more demanding for the RV than the LV, requiring real experience with acquisition, cropping, and measurement. 3D speckle-tracking is a further, still-emerging extension of this approach.

The Key Mimic: Athletic RV Remodeling

High-intensity exercise training alone can produce RV dilation, prominent trabeculation, and even a hyperreflective moderator band — genuinely overlapping with the structural findings used to diagnose ARVC. This overlap is a real reason ARVC can be delayed or missed in young, highly trained patients: a prospective study of sudden death under age 30 in the Veneto region of Italy found that 20% of fatal events were caused by previously undiagnosed ARVC.

Distinguishing the two requires integrating echo findings with detailed personal and family history, and applying the Task Force Criteria excluding the RV structure and function components specifically to help separate physiologic adaptation from true disease — strain quantification holds real promise for sharpening this distinction further.

Other conditions can also mimic ARVC’s RV dilation and dysfunction — congenital heart disease, ischemic, infiltrative, valvular, or dilated cardiomyopathy, and pulmonary arterial hypertension all need to be considered and integrated with the full clinical picture, not just the echo findings in isolation. A relatively normal LV with normal pulmonary artery pressure is a supportive feature when ARVC itself is the leading diagnosis, since it helps exclude pulmonary hypertension or LV-driven secondary RV dysfunction as alternative explanations.

Beyond Echo: CMR, CT, and Biopsy

Cardiac MRI is recommended as the first-line test specifically for assessing the RV structural/functional criteria, given its superior sensitivity for this purpose and its unique ability to detect LV involvement — otherwise genuinely underestimated by applying the 2010 Task Force Criteria, which were built primarily around RV findings. CMR’s own limitations are worth knowing, though: fibrosis is technically difficult to detect in the thin RV wall, fat and fibrosis in the RV are not specific to ARVC on their own, and current CMR sequencing can’t simultaneously assess fat and fibrosis in the same acquisition — genuine reasons CMR complements rather than replaces a careful echo. CMR for ARVC also requires real technical expertise in both acquisition and interpretation, and should be performed at centers experienced with this specific disease.

CT wasn’t included in the original 2010 Task Force Criteria but can identify fatty epicardial deposition and trabecular enlargement with good spatial and temporal resolution, at a radiation dose that can be minimized (as low as 1–2 mSv) — though far less data exist for CT than for echo or CMR in this disease.

Endomyocardial biopsy is useful in the differential diagnosis against myocarditis and sarcoidosis — see Cardiac Sarcoidosis for the broader context on that specific differential, which can be a genuine diagnostic dilemma since both conditions produce RV-predominant disease with arrhythmia. Biopsy is particularly considered in sporadic cases, or when non-invasive assessment remains inconclusive.

Family Screening

Clinical testing in relatives of an affected patient frequently reveals findings that don’t meet full diagnostic criteria on their own, but still carry real weight given the genetic context. RV systolic dysfunction (global or regional), or ECG abnormalities — repolarization changes, prolonged terminal activation duration, low QRS voltage, frequent ventricular ectopy (over 500 per 24 hours), or non-sustained VT — in a first-degree relative of an affected individual (or of a relative with autopsy-proven ARVC) is highly suggestive of ARVC and warrants close follow-up, even without meeting the full index-case criteria.

How to Diagnose It: A Practical Sequence

1. Measure the RVOT in both PLAX and PSAX views, recognizing PLAX’s genuine angle dependency, and compare against the major/minor Task Force thresholds.
2. Assess RV wall motion specifically for regional akinesia, dyskinesia, or aneurysm — the gatekeeping finding for both major and minor criteria — with particular attention to the triangle of dysplasia regions (apex, subpulmonic anterior wall, inferoposterior wall).
3. Quantify RV FAC from the apical four-chamber view whenever feasible, given its dual diagnostic and prognostic value, using an ultrasound-enhancing agent if endocardial definition is suboptimal.
4. Screen deliberately for structural features: trabecular derangement, a hyperreflective moderator band, focal wall thinning, and localized aneurysms or sacculations — these carry real diagnostic weight beyond chamber size and function alone.
5. Don’t stop at the RV — assess the LV specifically, particularly the inferolateral wall, given how commonly biventricular involvement is present even when not clinically obvious.
6. Add strain imaging when available, particularly in relatives, genotype-positive individuals, or borderline cases not yet meeting full Task Force Criteria — abnormal strain can precede overt dysfunction.
7. Actively consider athletic remodeling in young, highly trained patients, applying the Task Force Criteria excluding RV structure/function and integrating detailed personal and family history before attributing findings to training alone.
8. Correlate with ECG and clinical presentation — LBBB-morphology ventricular ectopy, right precordial T-wave inversion, and a history of palpitations, syncope, or aborted sudden death all support the diagnosis — while using epsilon waves and SAECG findings cautiously given their real limitations.
9. Recommend CMR when the diagnosis remains genuinely uncertain, specifically to better characterize RV findings and assess for LV involvement, at a center experienced with this disease.
10. For first-degree relatives, apply a lower diagnostic threshold — even non-diagnostic RV dysfunction or supportive ECG findings warrant close follow-up rather than reassurance.

Clinical Importance

ARVC rewards the same discipline this whole section has built toward: real, quantified thresholds instead of qualitative impressions, an honest accounting of which tools work early in disease versus only late (TAPSE and S′ late, strain and FAC earlier), and active consideration of the mimics — athletic remodeling most importantly — that can send the diagnosis in the wrong direction in either direction. Its genuinely biventricular nature, now widely recognized, is the clearest reminder in this entire section that a disease’s name doesn’t have to limit where you actually look.