Enter your search text in the box above

Select a result to preview

#channelopathies #inherited-arrhythmias #sudden-cardiac-death #CPVT

Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)

Overview

CPVT is a channelopathy characterised by exercise- or emotion-triggered polymorphic or bidirectional ventricular tachycardia in the absence of structural heart disease or QT prolongation at rest. It is one of the most prevalent causes of SCD in individuals <35 years without structural heart disease, responsible for ~15% of sudden cardiac deaths in youth. The arrhythmic substrate is adrenergic-driven SR calcium overload → diastolic calcium release → delayed afterdepolarisations → triggered VT. Management is a stepwise escalation from beta-blockers through flecainide, LCSD, and ICD — with variant-specific response rates now defining the starting point for therapy decisions.

Epidemiology

Genetics

Pathophysiology

RYR2 (CPVT1) — DAD Mechanism

RYR2 GOF → SR Ca²⁺ overload during adrenergic stimulation → spontaneous diastolic Ca²⁺ sparks coalesce into intracellular Ca²⁺ waves → NCX1 (Na⁺/Ca²⁺ exchanger) forward mode activated (extrudes 1 Ca²⁺, imports 3 Na⁺ = net inward depolarising current) → delayed afterdepolarisation (DAD) → if DAD amplitude exceeds INa activation threshold → triggered action potential → salvos of triggered APs produce bidirectional VT. The bidirectional VT morphology reflects alternating bundle-branch exit blocks from Purkinje system triggered activity, not epicardial origin. (sources/channelopathies-jaha-2025, sources/membrane-potential-physrev-2021, rating: very high)

CASQ2 (CPVT2) — Calcium Release Unit

Calsequestrin-2 functions within a quaternary calcium release unit (RYR2 + CASQ2 + triadin + junctin) anchored in the junctional SR. CASQ2 normally buffers luminal SR Ca²⁺ and inhibits RYR2 in the closed state via triadin and junctin. CASQ2 LOF (misfolding, impaired polymerisation, or protein absence) disrupts this inhibitory signalling → RYR2 loses Ca²⁺-dependent gate control → spontaneous release even at lower SR Ca²⁺ loads → same NCX-DAD-triggered AP sequence as CPVT1, but without calsequestrin Ca²⁺ buffering, producing earlier onset and greater severity. (sources/channelopathies-jaha-2025, sources/membrane-potential-physrev-2021)

TECRL (CPVT3) — Mixed CPVT/LQTS Phenotype

TECRL encodes an oxidoreductase enzyme localised to the endoplasmic reticulum. Autosomal recessive. Homozygous TECRL pathogenic variants reduce RYR2 and CASQ2 protein levels → reduced SR calcium storage and aberrant calcium handling. The clinical phenotype is a distinctive overlap of CPVT and LQTS features — adrenergically triggered bidirectional VT coexisting with QT prolongation — making TECRL disease phenotypically distinct from CPVT1 and CPVT2. (sources/genetics-va-fcvm-2022, rating: medium)

CALM1/2/3 — Calmodulinopathy CPVT Subtype

Mutations in CALM1, CALM2, or CALM3 (all encoding identical calmodulin protein) can produce a CPVT phenotype via a mechanism distinct from RYR2 GOF. Calmodulin (CaM) is constitutively pre-bound to RyR2 in the apo form; this apo-CaM stabilises the RyR2 closed state by allosterically reinforcing the "zipping" interaction between N-terminal and central RyR2 domains — a Ca²⁺-independent mechanism. Specific CPVT-associated mutations (CALM1-p.N98S, CALM1-p.N54I, CALM3-p.A103V) alter the 3D CaM–RyR2 binding interface and disrupt this stabilisation → spontaneous Ca²⁺ waves → NCX-mediated transient inward current (ITI) → DADs → bidirectional VT. These mutations differ from LQTS calmodulin mutations in producing only a small reduction in C-lobe Ca²⁺ affinity (CDI is relatively preserved). ClinGen classifies CALM1/2/3 as Moderate evidence for CPVT. Neonatal-onset bidirectional VT or unexplained CPVT-like arrhythmia — especially de novo — should prompt CALM1/2/3 sequencing. See concepts/Calmodulinopathy for full mechanism detail. (sources/CALM-FCVM-2018, rating: high; sources/clingen-summary-2026-05-09, rating: high)

ECG and Diagnosis

Giudicessi Diagnostic Scorecard

Pre-test probability scoring tool for CPVT1 (RyR2-mediated). Requires ≥1 exercise stress test or ambulatory Holter finding. Key utility: integrating clinical phenotype into RYR2 VUS adjudication reduces the VUS rate from 48% to 7%. (sources/cpvt-jcm-2024)

Category Finding Points
Symptoms Exercise/activity-associated ACA/SCA +2
Exercise/activity-associated syncope or seizures +1
Exercise/Holter Bidirectional VT at HR >100 bpm +4
PVCs in bigeminy + bidirectional couplets at HR >100 bpm +2
PVCs at HR >100 bpm +1
QTc ≤420 ms +0.5
421–459 ms 0
≥460 ms −0.5
Genetic test Pathogenic variant +4
Likely pathogenic variant +2
VUS 0
Negative (RYR2/CASQ2/TRDN/CALM1-3) −1
Holter Ambulatory ectopy >2% of beats −1
Imaging Ischemic/structural disease −2
Age ≥50 at sentinel event −1
Family Hx 1st-degree relative with definite CPVT +1.5
Suspicious autopsy-negative SCD (exertional/drowning) in 1st/2nd-degree relative ≤45 +1
Unexplained autopsy-negative SCD in 1st/2nd-degree relative ≤45 +0.5

Interpretation: ≥3.5 pts = definite/probable CPVT (≥90% likelihood); 2–3 pts = possible CPVT (~50%); 0.5–1.5 = nondiagnostic; ≤0 = no CPVT evidence.

Risk Stratification — Variant-Specific Outcomes

Chang 2025 — Largest CPVT Clinical Database (n=964, Marks Lab)

Systematic review of 221 publications (through Oct 2020): 964 CPVT patients with 263 unique RYR2 protein-coding variants. (sources/RYR2-CPVT-CircEP-2025, rating: very high)

Variant-specific beta-blocker efficacy:

Variant BB effective Notes
p.G2337V 10/11 (91%) Highly responsive; monotherapy often sufficient
p.R420W 5/17 (29%) Poorly responsive; early flecainide escalation
p.C2277R 2/8 (25%) Poorly responsive; combination from outset

Variant-specific flecainide use (post-2013):

Variant Flecainide + BB
p.R420W 7/9
p.C2277R 6/8
p.S2246L 3/4
p.G357S 0/91
p.G2337V 0/21

Variant-specific ICD implantation rates:

Variant ICD implanted
p.S2246L 7/9 — highest risk
p.R420Q 13/24
p.G357S 1/94 — predominantly benign
p.G2337V 1/21 — predominantly benign

Management

Beta-Blockers (First Line)

Non-selective beta-blockers (nadolol or propranolol) are Class I for all patients with a clinical CPVT diagnosis (ESC 2022). Non-selective agents preferred over selective BB — complete beta-1 and beta-2 blockade is required to suppress adrenergic-driven SR calcium overload. ~30% of patients require therapy beyond beta-blockers; variant-specific response data (see Risk Stratification) should guide early escalation decisions rather than waiting for breakthrough events. (sources/VA-SCD-ESC-2022, sources/RYR2-CPVT-CircEP-2025)

Flecainide (First Add-On)

Flecainide added to beta-blockers is the standard escalation for inadequate CPVT control. ESC 2022: ICD + flecainide + BB after aborted cardiac arrest is Class I (upgraded from IIa in 2022). Variant-specific flecainide use rates from Chang 2025 demonstrate that p.R420W, p.C2277R, and p.S2246L require flecainide combination in the majority of cases, while p.G357S and p.G2337V rarely need it. (sources/VA-SCD-ESC-2022, sources/RYR2-CPVT-CircEP-2025)

Mechanism of flecainide in CPVT (contested, clinically effective regardless):
Three competing mechanistic lines: (1) antiarrhythmic via Na⁺ channel blockade without affecting Ca²⁺ homeostasis (Liu 2011); (2) direct RYR2 open-state blockade — Hilliard 2010 showed flecainide inhibits RYR2 Ca²⁺ release channels by open-state blockade, reducing spark Ca²⁺ mass without compensatory SR Ca²⁺ loading, preventing diastolic Ca²⁺ waves; (3) no direct RYR2 channel effect (Bannister 2016). Clinical efficacy is established; primary mechanism remains unresolved. (sources/RYR2-CPVT-CircEP-2025, sources/flecainide-af-europace-2011)

LCSD — Surgical Escalation

Left cardiac sympathetic denervation (Class IIa, ESC 2022 — upgraded from IIb) when flecainide + beta-blockers are ineffective, not tolerated, or contraindicated. Surgical removal of the left stellate ganglion and lower thoracic sympathetic chain reduces noradrenaline release at the myocardium, directly attenuating the adrenergic trigger for diastolic calcium release. Particularly important in CPVT where ICD carries unique proarrhythmia risk. (sources/VA-SCD-ESC-2022)

Other Pharmacological Options (Limited Evidence)

ICD — Last Resort with Unique Proarrhythmia Risk

ICD shocks cause catecholamine surges that directly exacerbate CPVT arrhythmia — adrenergic storm triggered by the shock drives further RYR2 Ca²⁺ release → more DADs → more VT → more shocks. This ICD-proarrhythmia risk is unique to CPVT and does not apply to most other arrhythmia indications. Polymorphic VT and bidirectional VT shocks fail in 99% of cases; VF shocks succeed in 94%. (sources/cpvt-jcm-2024)

ESC 2022 indications:

Contemporary outcome data — paradigm shift toward last resort:

Catheter Ablation

Adjunctive therapy for patients who cannot receive flecainide or have refractory arrhythmias; not curative — arrhythmogenic substrate is not fully eliminated. (sources/cpvt-jcm-2024)

Sports and Exercise (AHA/ACC 2025)

A major paradigm shift from prior universal exercise restriction toward stratified shared-decision-making (SDM) based on genotype and stress test response. (sources/competitive-sports-aha-2025, rating: very high)

See concepts/Sports-Cardiology-SDM for full SDM framework.

ESC 2022 Guideline Summary

Special Entities

Ca²⁺ Release Deficiency Syndrome (CRDS)

A newly described RYR2 loss-of-function phenotypic spectrum distinct from classical CPVT. CRDS patients do not exhibit typical exercise-induced bidirectional VT; instead they present with short-coupled ventricular torsades-de-pointes arrhythmias. RYR2 exon 3 deletion has been associated with LVNC overlap and atypical CPVT. LOF RYR2 variants reduce Ca²⁺ release (vs. the GOF excess release in CPVT1), producing a clinically distinct arrhythmia syndrome that may be misclassified as idiopathic VF on standard workup. (sources/arrhythmia-genetics-mgenetik-2025)

Emerging Therapies

AAV-Based Gene Therapy

CRISPR/Cas9 Gene Editing

CPVT in Pregnancy

Contradictions / Open Questions

Connections

Sources