Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)
Details
CPVT is an inherited arrhythmia syndrome defined by exercise- or emotion-triggered polymorphic or bidirectional ventricular tachycardia in a structurally normal heart with a normal resting QT interval — the normal resting ECG being precisely why it is missed. Gain-of-function RYR2 variants cause 60–70% of cases, with loss-of-function CASQ2 and the rarer TECRL, TRDN and calmodulin genes accounting for most of the rest; all converge on diastolic sarcoplasmic reticulum calcium leak, delayed afterdepolarisations and triggered ventricular arrhythmia. It accounts for up to 15% of sudden cardiac death under 35 and carries 30–50% mortality by that age if unrecognised. Management escalates in a fixed order — non-selective beta-blockade for everyone, flecainide next, sympathetic denervation before devices — and the ICD is now a last resort precisely because its shocks aggravate the arrhythmia they treat.
Key Facts
Epidemiology
- Prevalence ~1:10,000, accounting for up to 15% of sudden cardiac death under 35, 12% of autopsy-negative sudden unexplained death in the young, and some SIDS cases. (sources/cpvt-jcm-2024, rating: medium; sources/channelopathies-jaha-2025, rating: high)
- Onset is in childhood: mean age 7–12 years, with >60% having had a first syncope or cardiac arrest by age 20. Late onset in the third or fourth decade is recognised and does not exclude the diagnosis. (sources/cpvt-jcm-2024)
- Males present in childhood and adolescence; females around age 20. The reversal of the usual male excess is one reason CPVT is under-recognised in women. (sources/cpvt-jcm-2024)
- A negative family history proves nothing: ~30% have a family history of stress-related syncope, seizure or SCD in relatives under 40, rising to 60% in RYR2 families, and the rest present de novo. (sources/cpvt-jcm-2024)
- Diagnosis is late — the mean interval from first symptom to diagnosis is 2 ± 0.8 years, and many of those years are spent with the wrong diagnosis.
Genetics
| Gene | Subtype | Inheritance | Share of CPVT | ClinGen validity | Note |
|---|---|---|---|---|---|
| RYR2 | CPVT1 | Autosomal dominant | 60–70% | Definitive | Gain-of-function missense in 96% |
| CASQ2 | CPVT2 | Autosomal recessive | 2–5% | Definitive (AR); Moderate (AD) | Earlier onset, greater beta-blocker resistance |
| TECRL | CPVT3 | Autosomal recessive | <1% | Definitive | CPVT/LQTS overlap phenotype |
| TRDN | CPVT5 | Autosomal recessive | <1% | Definitive | Triadin loss-of-function |
| CALM1, CALM3 | CPVT4, CPVT6 | Autosomal dominant | <1% | Moderate | Calmodulinopathy; neonatal bidirectional VT |
| PKP2, KCNJ2, ANK2 | — | — | — | Disputed | Older literature only; not causal without corroboration |
(sources/clingen-summary-2026-05-09, rating: high; sources/cpvt-jcm-2024)
- The definitive gene list is short — RYR2, biallelic CASQ2, TECRL and TRDN. CALM1/2/3 are Moderate. PKP2 and KCNJ2 were disputed in 01/2021 and ANK2 likewise, all three having been attributed to CPVT in older literature; see concepts/ClinGen-Gene-Disease-Validity.
- Penetrance is 63–78% overall, 75–80% for RYR2 and 100% for biallelic CASQ2 — so a genotype-positive relative is managed as CPVT rather than observed.
- De novo variants are the majority of monogenic cases and produce earlier, more severe disease than familial ones. Genetic testing is warranted with no family history at all.
- The 2020 Primer gives RYR2's share as 65% of probands (CPVT1), with CASQ2 the rarer but more severe autosomal recessive CPVT2, and CALM1/CALM2, TRDN, TECRL and ANK2/KCNJ2 accounting for overlapping exercise-induced phenotypes. Its recommended panel covers all 105 translated RYR2 exons plus CASQ2, KCNJ2, CALM1/2/3, TRDN, TECRL and PKP2 — the last because PKP2-ARVC has a pre-cardiomyopathic electrical phase that mimics CPVT. (sources/inherited-arrhythmias-nrdp-2020, rating: very high)
- About one-third of clinically diagnosed CPVT has no identifiable gene, so a negative panel does not exclude the disease, and undiscovered CPVT genes are presumed. (sources/inherited-arrhythmias-nrdp-2020)
- An incidentally found variant is usually not disease. In 6,517 unselected clinical exome referrals 8.8% carried a rare RYR2 or CASQ2 variant, 97.7% of them VUS, versus 6.0% of ExAC controls and 60.1% of clinically robust CPVT cases — and none of 140 variant-positive paediatric referrals with low pre-test suspicion had clinical CPVT. Exome variants overlapped control residues far more than case residues (60.4% vs 7.9%). A targeted CPVT panel, not exome, is the right test, and an asymptomatic VUS is neither a diagnosis nor a licence for cascade testing. (sources/cpvt-exome-circep-2017, rating: high)
- RYR2 spans two opposite diseases. Gain-of-function causes CPVT; loss-of-function causes calcium release deficiency syndrome — short-coupled torsades at rest, sometimes mislabelled idiopathic VF, with exon 3 deletion overlapping LVNC. Variant direction cannot be inferred from position. (sources/arrhythmia-genetics-mgenetik-2025, rating: high)
- Variant-level detail lives with the genes — hotspot architecture, domain-by-domain age of onset, the Chang 2025 catalogue and ClinGen validity by phenotype: see entities/RYR2 and entities/CASQ2.
Pathophysiology
Adrenergic stimulation of a leaky RYR2 loads the sarcoplasmic reticulum until spontaneous diastolic calcium sparks coalesce into waves; NCX1 then extrudes one Ca²⁺ in exchange for three Na⁺, a net inward current that produces the delayed afterdepolarisation; when the DAD reaches the sodium current threshold it fires a triggered action potential, and salvos of triggered beats give bidirectional VT. The alternating morphology reflects alternating bundle-branch exit from Purkinje triggered activity, not an epicardial focus. (sources/membrane-potential-physrev-2021, rating: very high; sources/channelopathies-jaha-2025)
| Gene | Primary defect | Route to the DAD |
|---|---|---|
| RYR2 (CPVT1) | Channel open probability rises in diastole | Calcium leak → NCX inward current |
| CASQ2 (CPVT2) | Lost luminal buffering and lost RYR2 inhibition via triadin/junctin | Release at a lower SR load → NCX |
| TECRL (CPVT3) | ER oxidoreductase loss reduces RYR2 and CASQ2 protein | Same pathway, plus QT prolongation |
| CALM1/2/3 | Apo-calmodulin fails to stabilise the RYR2 closed state | Destabilised channel → waves → NCX |
- The two-hit CASQ2 mechanism explains its severity: with buffering and inhibitory signalling both lost, release occurs at lower SR calcium load and beta-blockade has less to work with. (sources/channelopathies-jaha-2025)
- Two accounts of the polymorphic transition remain. The wedge model holds that epicardial ectopy reverses activation, raises Tpeak–Tend and spatial dispersion of repolarisation, and permits reentry (propranolol and verapamil suppressed all activity in wedge preparations); the transgenic-mouse model instead implicates His–Purkinje DAD-triggered focal activity. The Primer leaves both hypotheses standing. (sources/inherited-arrhythmias-nrdp-2020, rating: very high)
- Calmodulinopathy CPVT is a regulatory-partner disease, not a channel disease — the RYR2 gene is normal, and the loss is of the apo-calmodulin pool that stabilises the channel's closed state (sources/calm-fcvm-2018, rating: high). Mechanism and phenotype: concepts/Calmodulinopathy.
- TECRL changes the label as well as the mechanism: adrenergic bidirectional VT with QT prolongation, an overlap with LQTS that makes it phenotypically distinct from CPVT1 and CPVT2. (sources/genetics-va-fcvm-2022, rating: medium)
Clinical Presentation
- Exertional or emotional syncope is the commonest first event, and about one-third of VT episodes degenerate to VF — so the first presentation may be cardiac arrest. (sources/cpvt-jcm-2024)
- 30% have had at least one cardiac arrest before diagnosis and up to 80% at least one syncope. The disease announces itself; it is the label that arrives late.
- Seizure-like activity during syncope buys the wrong diagnosis. CPVT is routinely managed as epilepsy or vasovagal syncope, and the resting ECG is normal — so a young person with exertional collapse needs an exercise test, not reassurance. (sources/channelopathies-jaha-2025)
- Early repolarisation on the ECG marks a more symptomatic presentation, and NSVT on exercise testing a worse outcome — though some arrests occur in patients with a clean stress test. (sources/cpvt-jcm-2024)
ECG and Diagnosis
The HRS consensus offers four routes to diagnosis (sources/cpvt-jcm-2024):
- Structurally normal heart, normal ECG, and unexplained exercise- or catecholamine-induced bidirectional VT or polymorphic PVCs in a patient under 40.
- A pathogenic variant in a CPVT gene, in a proband or a relative.
- A relative of an index case, with a normal heart and exercise-induced PVCs or bidirectional/polymorphic VT.
- Criterion 1 in a patient over 40, once coronary and structural disease are excluded.
| Test | Role | Performance |
|---|---|---|
| Resting ECG | Normal by definition | Excludes LQTS; may show early repolarisation |
| Exercise stress test | Primary diagnostic test | Provokes VT in ~2/3 |
| Burst exercise protocol | Higher sensitivity | Standard protocol equivocal |
| Epinephrine challenge | Only when exercise is not possible | Sensitivity 28%, specificity 98% |
| 24-h Holter | Ambient burden and trigger capture | Less sensitive than exercise |
| Genetic testing | All probands and first-degree relatives | Positive in 60–70% of CPVT1 |
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The characteristic stress-test sequence is diagnostic even without bidirectional VT: sinus rhythm at rest, then unifocal PVCs appearing at ~110–130 bpm, progressing to bigeminy, couplets, bidirectional couplets, then non-sustained or polymorphic VT at higher rates — often ceasing at peak exercise or immediately in recovery. If the history and echo are consistent, exercise-induced ectopy culminating in bidirectional couplets makes CPVT very likely even if full bidirectional VT never occurs. (sources/inherited-arrhythmias-nrdp-2020, rating: very high)
-
A rare RYR2 missense sits in 3% of healthy people, so a compelling phenotype gives only ~20:1 odds that the variant is causal — the reason the exercise test, not the panel, is the diagnostic arbiter. Per the 2013 HRS/EHRA/APHRS consensus, a CPVT1 pathogenic variant is equivalent to a clinical diagnosis and compels cascade testing plus consideration of prophylactic beta-blockade in asymptomatic carriers. (sources/inherited-arrhythmias-nrdp-2020)
-
PVC morphology matters more than count: late-coupled, LBBB pattern with inferior axis (most sensitive and specific), larger burden, first appearance at higher workload, bigeminy at peak stress, QRS >120 ms, coupling interval >400 ms, and disappearance within the first minute of recovery. (sources/cpvt-jcm-2024)
-
CPET adds a mechanistic clue — the ventilatory anaerobic threshold consistently precedes ectopy, suggesting the shift to anaerobic metabolism contributes to arrhythmogenesis.
-
Epinephrine is not a substitute for exercise testing: in 81 patients it missed up to 70% of RYR2 carriers who failed to reach target heart rate. Protocol and criteria: concepts/Pharmacological-Provocation-Testing. (sources/pharmacological-provocation-europace-2025, rating: high)
-
Bidirectional VT is the hallmark but not the whole phenotype — its differential, including Andersen-Tawil syndrome: concepts/Bidirectional-Ventricular-Tachycardia.
Giudicessi Diagnostic Scorecard
A pre-test probability tool for RYR2-mediated CPVT that requires at least one exercise or Holter finding. Its practical value is variant adjudication: integrating phenotype reduces the RYR2 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 | Ischaemic/structural disease | −2 |
| Age | ≥50 at sentinel event | −1 |
| Family history | First-degree relative with definite CPVT | +1.5 |
| Suspicious autopsy-negative SCD (exertional, drowning) in first/second-degree relative ≤45 | +1 | |
| Unexplained autopsy-negative SCD in first/second-degree relative ≤45 | +0.5 |
Interpretation: ≥3.5 points = definite/probable CPVT (≥90% likelihood); 2–3 = possible (~50%); 0.5–1.5 = nondiagnostic; ≤0 = no CPVT evidence.
Risk Stratification
Risk is carried by the patient and by the variant, and the variant signal is now strong enough to decide which drug comes second.
- Patient-level predictors of adverse events: younger age at diagnosis, proband status, multiple variants, autosomal recessive inheritance, prior aborted cardiac arrest, and absent or incomplete beta-blockade. (sources/cpvt-jcm-2024)
Variant-level outcomes — six variants had enough patients to compare, and the differences are wide enough to decide whether the second drug should wait for a breakthrough event:
| Variant | Beta-blocker effective | Flecainide added (post-2013) | ICD implanted | Reading |
|---|---|---|---|---|
| p.G2337V | 10/11 (91%) | 0/21 | 1/21 | Most responsive; monotherapy often sufficient |
| p.G357S | — | 0/91 | 1/94 | Commonest variant; predominantly benign |
| p.R420Q | — | — | 13/24 | Intermediate |
| p.R420W | 5/17 (29%) | 7/9 | — | Poorly responsive; escalate early |
| p.C2277R | 2/8 (25%) | 6/8 | — | Poorly responsive; combine from the outset |
| p.S2246L | — | 3/4 | 7/9 | Highest-risk variant |
(sources/RYR2-CPVT-CircEP-2025, rating: very high)
- A dash means the cohort reported no figure for that cell, not that the treatment was unnecessary — the three columns come from different subsets of patients.
- Sample size is the weakness. Each variant rests on 3 to 91 patients drawn from heterogeneous publications — the residue-level contrasts are biologically convincing but not guideline-grade.
- Penetrance differs within the same gene: every p.M3978I carrier is symptomatic; p.G155R carriers are almost all asymptomatic except one 16-year-old sports-related sudden death. The molecular basis is unknown, and it is why cascade counselling cannot be variant-agnostic.
- Queryable resource: markslab-cpvtdb.org offers per-variant outcomes with 3D RYR2 structure. Domain architecture and structural mechanisms: entities/RYR2.
Beta-Blockers
- Non-selective beta-blockade is the foundation of therapy in every patient with a clinical diagnosis: nadolol or propranolol, because complete beta-1 and beta-2 blockade is what suppresses adrenergic calcium overload. (sources/VA-SCD-ESC-2022, rating: very high)
- Nadolol 1–2 mg/kg/day is preferred. Beta-1-selective agents carry a HR 2.04 (p=0.002) for events versus nadolol in symptomatic children and HR 5.8 (p=0.001) in a 216-patient multinational RYR2 cohort; nadolol and propranolol do not differ. (sources/cpvt-jcm-2024)
- About 30% escalate beyond beta-blockers. The variant table above argues for escalating early in a predicted non-responder rather than waiting for a breakthrough event.
- Non-adherence is a therapeutic problem, not a compliance footnote: 15% of an international cohort were non-adherent, and 60% of evening-hour cardiac events were attributed to missed doses.
- A beta-blocker-free strategy is narrow but real: 10% of the international registry could not tolerate beta-blockers, and a no-beta-blocker course is defensible only in an asymptomatic patient with no bigeminy, couplets or complex ectopy on stress testing.
Flecainide
- Added to beta-blockade when control is inadequate — the variant table above identifies the genotypes that need it. (sources/VA-SCD-ESC-2022)
- The mechanism is contested and does not change management: sodium channel blockade alone, direct RYR2 open-state blockade, and no direct RYR2 effect have each been demonstrated. Efficacy is established; the route is not. (sources/flecainide-af-europace-2011, rating: medium; sources/RYR2-CPVT-CircEP-2025)
- Dosing, proarrhythmia and monitoring: entities/Flecainide.
Left Cardiac Sympathetic Denervation
- Offered when beta-blockade plus flecainide is ineffective, not tolerated or contraindicated. It removes the noradrenaline release that triggers diastolic calcium release, and its practical advantage over a tablet is that it works on the evening dose the patient forgot. (sources/VA-SCD-ESC-2022)
- The largest series (n=63) saw major cardiac events fall from 86% to 21% over a median 37 months — an annual event rate of 3.4 to 0.5 per patient-year, a 92% reduction — with one-third of previously refractory patients still having events. (sources/cpvt-jcm-2024)
- Triple therapy — nadolol, flecainide and LCSD — is the consensus first-line approach after a sentinel cardiac arrest, because denervation insures against the consequence of a single missed dose.
- Not curative and never standalone. Bilateral denervation is reserved for failure of LCSD alone or recurrent shocks. Procedure, complications and the LQTS evidence base: concepts/Left-Cardiac-Sympathetic-Denervation.
Other Pharmacological Options
| Drug | Evidence | Verdict |
|---|---|---|
| Propafenone | Case reports only | Not established |
| Verapamil | Early small studies promising; longer follow-up showed no benefit | Rarely used |
| Ivabradine | Tested with nadolol or flecainide; no reduction in DADs or delayed arrhythmias in animal models | Not a CPVT treatment |
| Dantrolene | Attenuates abnormal calcium handling in animal models only | No human data |
ICD Therapy
- The shock is the harm. A shock produces a catecholamine surge that drives further RYR2 calcium release, more DADs and more VT — a proarrhythmic feedback loop peculiar to CPVT. Bidirectional and polymorphic VT shocks fail in 99% of cases; VF shocks succeed in 94%, so the device treats only the terminal rhythm. (sources/cpvt-jcm-2024)
- Contemporary outcomes argue for last resort: a meta-analysis of 53 studies (n=1,429, 35% with an ICD) found 40% with ≥1 appropriate shock, 21% with ≥1 inappropriate shock and 20% with electrical storm, and 60% of the seven deaths were attributed to ICD-associated incessant VT.
- The registry comparison is confounded: 47% adverse outcomes with an ICD versus 15.8% without, but the no-ICD group received more nadolol/propranolol and more guideline-directed therapy. It argues for optimising drugs, not for withholding a device.
- Programming matters more than in other diseases — a single VF zone at 230–300 bpm and no VT zone, to avoid treating PVCs and self-terminating bidirectional VT; a single-chamber transvenous device is generally adequate. Inappropriate shocks affect 20–30%, nearly half of them from AF or NSVT that would have self-terminated. The subcutaneous device performs comparably in the EFFORTLESS registry (5.5% CPVT), but transvenous is preferred when a device is indicated.
- Expert opinion now places denervation before the device: an ICD should not be implanted without prior LCSD, and PACES gives a Class IIa recommendation to pharmacological therapy or sympathetic denervation without an ICD even when aborted cardiac arrest is the presentation.
Catheter Ablation
- Adjunctive and not curative — the substrate is intracellular calcium handling rather than a focal scar, so ablation can only target the triggering beats. (sources/cpvt-jcm-2024)
- The origin is disputed: the largest series (n=14) found LV basal anterior and LV septal sources with biventricular triggering beats in a third, contrary to earlier reports of RVOT predominance. More than 90% were non-inducible acutely, ~60% were syncope-free at follow-up, and recurrences clustered beyond the first year.
- Beta-blockers remain mandatory after ablation, and induction of non-triggering PVCs after the procedure predicts syncope recurrence — an indication for early LCSD or an ICD.
Pregnancy
- Non-selective beta-blockade continues through pregnancy and for at least 40 weeks postpartum — the postpartum period is the high-risk window. (sources/cv-pregnancy-esc-2018, rating: very high)
- Selective agents are acceptable only in a patient with no prior syncope and no confirmed CPVT event.
- Delivery is a medium-risk (Level 2) event: tertiary centre, IV access, IV beta-blocker drawn up, external defibrillator on site. Unlike LQTS, CPVT does warrant intrapartum telemetry, because arrhythmia can appear and escalate from isolated PVCs to unstable VT during labour. (sources/inherited-arrhythmias-nrdp-2020, rating: very high)
- The single available pregnancy study found no augmented maternal risk during or after pregnancy — the evidence base for CPVT in pregnancy is far thinner than for LQTS. (sources/inherited-arrhythmias-nrdp-2020)
- New VT in pregnancy or postpartum requires exclusion of structural disease and peripartum cardiomyopathy before CPVT is assumed. If a device indication emerges, a single-chamber ICD is preferred, placed with echocardiographic or electroanatomical guidance.
Sports and Exercise
The 2025 AHA/ACC statement replaced universal restriction with genotype- and stress-test-stratified shared decision-making. (sources/competitive-sports-aha-2025, rating: very high)
| Phenotype | Competitive sport |
|---|---|
| Gene-positive, no exercise-induced ectopy on burst testing | Reasonable, after discussing prophylactic beta-blocker ± flecainide |
| Asymptomatic with exercise-induced ectopy | May be considered once beta-blocker + flecainide have normalised the stress test |
| Previously symptomatic | Requires beta-blocker + flecainide ± LCSD and a normalised stress test; reassess every 6–12 months |
- Adequate suppression means ideally no ectopy — bigeminal PVCs may be acceptable; couplets or NSVT require intensification first.
- Burst exercise stress testing once or twice a year in every CPVT athlete.
- An ICD is never implanted solely to permit sport: the adrenergic storm after a shock worsens CPVT, and the inappropriate shock risk is ~5% per year.
- Full framework: concepts/Sports-Cardiology-SDM.
ESC 2022 Recommendations
| Recommendation | Class |
|---|---|
| Non-selective beta-blockers in every patient with a clinical diagnosis | I |
| Avoid competitive and strenuous exercise and stressful environments | I |
| ICD + beta-blocker + flecainide after aborted cardiac arrest | I |
| ICD for arrhythmic syncope or bidirectional/polymorphic VT despite maximally tolerated beta-blocker + flecainide | IIa |
| LCSD when beta-blocker + flecainide are ineffective, not tolerated or contraindicated | IIa |
| Epinephrine or isoproterenol challenge when exercise testing is not possible | IIb |
| Programmed electrical stimulation for SCD risk stratification | III — not recommended |
(sources/VA-SCD-ESC-2022, rating: very high)
Emerging Therapies
The gene is too large to replace — RYR2 is ~15,000 nt against an AAV capacity of ~4.7 kb — so every RYR2 strategy works around the gene rather than on it. (sources/gene-therapy-arrhythmia-2025, rating: high)
| Strategy | What it does | Stage reached |
|---|---|---|
| AAV9-CASQ2 replacement | Restores the calcium release unit in CPVT2 | Abolished adrenergic VT in knockout mice; >85% reduction for ≥1 year in the R33Q knock-in |
| CASQ2 overexpression in CPVT1 | Raises RYR2 refractoriness without touching RYR2 | Suppressed arrhythmia in RYR2 models; 1.5–2-fold above wild type predicted sufficient |
| CaMKII inhibitory peptide (AIP) | Mutation-agnostic pathway modulation | Eliminated vulnerability in R176Q mice; peptide specificity limits it |
| Allele-specific siRNA | Silences the mutant allele | ~60% knockdown; repeated dosing needed |
| CRISPR-SaCas9 | Repairs the RYR2 variant | 41% editing; 0/7 treated versus 7/8 control mice arrhythmic |
(sources/gene-therapy-arrhythmia-2025; sources/gene-therapy-arrhythmia-cjca-2026, rating: high)
- NCT07148089 — AAV8-CASQ2 in RYR2-CPVT1, Phase Ib. ~18 patients in three cohorts (two adult dose-finding, then ages 7–17), with adverse events to one year and follow-up to five; the efficacy endpoint is the ventricular arrhythmia score on exercise testing at day 180. Participants continue optimal medical therapy, and the first two patients in each cohort have an ICD. Note the serotype change — AAV8 clinically, AAV9 preclinically.
- The trial is pathway modulation, not gene replacement. CASQ2 is overexpressed to increase RYR2 refractoriness, which sidesteps both the RYR2 size constraint and the variant-by-variant problem of silencing.
- Autosomal dominant CASQ2 disease is the untested case: variants that preserve dimerisation but block polymerisation are retained in the junctional SR and compromise wild-type protein as a poison peptide. Whether overexpression rescues them is unknown.
- The safety question the trial does not ask is CRDS — the loss-of-function phenotype of the gene every RYR2 strategy is reducing (see Contradictions).
- CPVT is a strong gene-editing candidate because pharmacological suppression is effective but not curative (sources/gene-editing-cv-tcm-2025, rating: medium). Framework: concepts/Gene-Editing-Risk-Benefit-Framework. Vector constraints: concepts/AAV-Gene-Delivery. Gene-level detail: entities/RYR2, entities/CASQ2.
Contradictions / Open Questions
- The ICD hierarchy was reshuffled between 2015 and 2022. ICD was Class I in 2015 for arrhythmic syncope or bidirectional/polymorphic VT on maximal therapy; in 2022 that dropped to IIa while ICD + flecainide + beta-blocker after aborted arrest rose to Class I. The large group of symptomatic patients who have not yet arrested sits in the gap. (sources/VA-SCD-ESC-2022, rating: very high)
- The device both treats and provokes. ICD shocks cause the catecholamine surge that worsens CPVT, yet aborted arrest still carries a Class I indication — two imperatives pointing in opposite directions for the same patient. (sources/channelopathies-jaha-2025, rating: high; sources/VA-SCD-ESC-2022)
- LCSD was upgraded from IIb to IIa on observational data alone, with no randomised trial and no prospectively validated threshold for operating.
- Variant-specific therapy: strong signal, thin samples. Per-variant groups of 3 to 91 patients from heterogeneous publications cannot support guideline-level recommendations, even when the residue-level contrasts are striking. (sources/RYR2-CPVT-CircEP-2025, rating: very high)
- Flecainide's mechanism in CPVT is unresolved — three competing findings, one established clinical effect.
- The ICD registry comparison does not settle the question. The 47% versus 15.8% difference is confounded by far better pharmacological therapy in the no-ICD group; it supports triple therapy, not device avoidance.
- Ablation targets are contested: RVOT in earlier case series, LV basal anterior and septal in the largest series, with a third biventricular. No prospective mapping study has established the targets systematically.
- Penetrance varies within a single gene — p.M3978I fully penetrant, p.G155R almost silent — and the molecular basis is unknown, which leaves cascade counselling resting on the variant's observed family rather than its biology.
- Every RYR2-silencing therapy risks creating CRDS, the loss-of-function phenotype of the same gene. The safety margin is a guess: no study has tested organ-level CRDS susceptibility in a treated animal, and the Phase Ib trial does not screen for it. (sources/gene-therapy-arrhythmia-cjca-2026, rating: high)
- RYR2's share of CPVT is quoted inconsistently — 60–70% in both CPVT reviews, 50–60% on entities/RYR2, whose source states 60–70% in the same document. The figure matters for pre-test probability when the panel is negative.
- A third of CPVT has no gene, yet universal beta-blockade is recommended for the rest. The Primer calls lifelong prophylactic treatment based solely on a positive genotype "wholly unsatisfying" — the risk-stratification tool that would let low-risk carriers off therapy does not exist, so every carrier is treated. (sources/inherited-arrhythmias-nrdp-2020, rating: very high)
- The ICD recommendation was already contracting in 2020. The Primer states ICD monotherapy should never be recommended and that triple therapy (nadolol, flecainide, LCSD) may match device survival without device morbidity — anticipating the 2022 downgrade of ICD to IIa in the symptomatic non-arrested group. (sources/inherited-arrhythmias-nrdp-2020)
- Two coexisting mechanisms, two therapeutic logics. The wedge model predicts anti-dispersion therapy (propranolol, verapamil) and the Purkinje-focus model predicts focal suppression; the field has not resolved which, so therapy targets the shared upstream event (adrenergic calcium release) rather than either downstream mechanism. (sources/inherited-arrhythmias-nrdp-2020)
- A universal CPVT therapy exists in principle but not in practice. CASQ2 overexpression and CaMKII inhibition both work across genotypes, solving the variant-by-variant problem — yet the trial in humans delivers CASQ2 itself, leaving the general approach untested.
Connections
- Related to entities/RYR2 — the CPVT1 gene, its variant landscape and its opposite loss-of-function phenotype
- Related to entities/CASQ2 — CPVT2, its severity and the most advanced gene-therapy target
- Related to concepts/Calmodulinopathy — the regulatory-partner form of CPVT
- Related to concepts/Bidirectional-Ventricular-Tachycardia — the hallmark arrhythmia and its differential
- Related to concepts/Pharmacological-Provocation-Testing — exercise and epinephrine testing
- Related to entities/Flecainide — the first add-on drug
- Related to concepts/Left-Cardiac-Sympathetic-Denervation — the surgical escalation
- Related to concepts/Electrical-Storm — the ICD-triggered adrenergic cascade
- Related to concepts/Sports-Cardiology-SDM — the 2025 activity framework
- Related to concepts/Sudden-Cardiac-Death — the outcome being prevented
- Related to concepts/Cardiogenetic-Centers — where exercise testing and family screening should happen
- Related to concepts/ClinGen-Gene-Disease-Validity — how the CPVT gene list was settled
- Related to concepts/Genetic-Testing-in-Arrhythmias — yield, the VUS problem, and why the stress test stays the diagnostic arbiter
- Related to concepts/AAV-Gene-Delivery — packaging constraints on gene therapy
- Related to concepts/Gene-Silencing-Therapy — allele-specific knockdown
- Related to concepts/CRISPR-Cas9-in-Channelopathies — editing the variant itself
- Related to concepts/Gene-Editing-Risk-Benefit-Framework — how editing candidacy is assessed
- Related to concepts/iPSC-Derived-Cardiomyocytes — the model system for mechanism and drug work
- Related to concepts/Electrical-Remodeling — the substrate consequences of chronic calcium leak
- Related to entities/Andersen-Tawil-Syndrome — the commonest mimic of bidirectional VT
Sources
Clinical review and diagnosis
- sources/cpvt-jcm-2024
- sources/channelopathies-jaha-2025
- sources/inherited-arrhythmias-nrdp-2020
- sources/pharmacological-provocation-europace-2025
Genetics and variant interpretation
- sources/RYR2-CPVT-CircEP-2025
- sources/cpvt-exome-circep-2017
- sources/clingen-summary-2026-05-09
- sources/arrhythmia-genetics-mgenetik-2025
- sources/genetics-va-fcvm-2022
- sources/calm-fcvm-2018
Guidelines and activity
Therapy and translational science
- sources/gene-therapy-arrhythmia-2025
- sources/gene-therapy-arrhythmia-cjca-2026
- sources/gene-editing-cv-tcm-2025
- sources/flecainide-af-europace-2011
Physiology