Arrhythmias & electrophysiology

Progressive conduction system disease preceding hypertrophy in IVS4+919G>A Fabry variant: a population-based electrocardiographic study

EuropacePublished population-based electrocardiographic study

Authors' conclusion

The IVS4+919G>A variant is characterized by a progressive electrical phenotype dominated by conduction system disease preceding hypertrophy without excess major arrhythmic events. Electrocardiographic surveillance and phenotype-based risk stratification may be more informative than structural assessment alone for identifying individuals at risk of device therapy. Institutional Review Board: CMUH113-REC3-076

Study context

Population
IVS4+919G>A Fabry variant carriers identified from a regional genetic screening programme, and age- and sex-matched controlsIVS4+919G>A carriers identified among 457,581 patients
Participants
905 carriers
Exposure
IVS4+919G>A carriers vs controls matched 1:2 by age and sex
  • IVS4+919G>A carriersn = 905
Outcome
Cumulative prevalence of IVS4+919G>A
Methodological detailsregional genetic screening programme, matched 1:2 to controls by age and sex
  • Regional genetic screening programme
  • Matched 1:2 to controls by age and sex

Main finding

As reported in the abstract

Cumulative prevalence

0.198%

Observational data: associations, not effects.

Further findings

OutcomeHR (95% CI)P value
Right bundle branch block and pacemaker implantation (males)IVS4+919G>A carriersvs controlsRight bundle branch block; malesvs male controls9.286 (5.16–16.70)P < 0.001
Right bundle branch block and pacemaker implantation (males)IVS4+919G>A carriersvs controlsPacemaker implantation; malesvs male controls9.197 (2.88–29.31)P < 0.001
Stroke and atrial fibrillation (males)Male carriersvs male controls; risk similar1.435 (0.69–2.96)P = 0.289
  • Right bundle branch block and pacemaker implantation (males): precedes the onset of echocardiographic left ventricular hypertrophy

Age-specific prevalence by sex

Age-specific prevalence in females ∼2.5-fold higher than in males (0.11-0.15%), without significant change throughout different age categories
∼2.5-fold

Catch-up phenomenon in female carriers · after the age of 60

Female carriers demonstrated the catch-up phenomenon after the age of 60

PR interval

PR interval did not shorten but was prolonged instead

Detection sensitivity: Electrocardiographic (ECG) (left ventricular hypertrophy combined with conduction abnormalities) vs echocardiographic criteria alone

ECG detection sensitivity
88%
Echocardiographic criteria alone
51.5%

Original publication

Progressive conduction system disease preceding hypertrophy in IVS4+919G>A Fabry variant: a population-based electrocardiographic study. Europace. Published 22 September 2026. doi:10.1093/europace/euag258

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