Abstract 2481: Idiopathic Ventricular Fibrillation: Clarifying a High-Risk Cohort
Introduction: Nearly one-third of sudden unexpected deaths (SUD) in the young are autopsy negative. Ventricular dysrhythmias are thought to contribute to SUD. Whether mitral valve prolapse (MVP) confers any susceptibility for SUD has been debated. We sought to determine the prevalence of ventricular ectopy (VE) and mitral valve (MV) abnormalities in a cohort of idiopathic ventricular fibrillation (IVF).
Methods: In this IRB-approved retrospective analysis, the electronic medical record (EMR) was used to identify patients (pts) who were evaluated in our Long QT Syndrome/Sudden Death Clinic between July 2000 and April 2009 and were diagnosed with channelopathy/cardiomyopathy-negative IVF. From the EMR, data from clinical notes, CV imaging reports, 12-lead and 24-hour ambulatory ECGs, and exercise stress tests were abstracted.
Results: Twenty of the >950 unique pts evaluated had IVF (age 31±14 yrs, average QTc 422±25 ms). All 20 had ICDs and most (75%) were female. IVF was the sentinel event in 95%. Ambulatory ECGs were available for review in 13 pts. Per hour, there were 151±225 VEs (range 0.2–604) including 4.5±10.8 couplets (range 0–41), 6.2±12.6 bigeminies (range 0–40), and 0.31±0.66 runs of nonsustained VT (range 0–2.39). Seven of 13 pts (54%) had PVC morphologies of outflow tract origin alternating with papillary muscle or fascicular origin. Five of these had very tight PVC coupling intervals. MV abnormalities were detected in 9 of 19 pts (47%) including 6 (32%) with bileaflet MVP (4 of these had ≥mild MR). Ectopic burden seemed independent of MV abnormalities. Over 1.9±3.1 years of follow-up following ICD placement, 6 have received VF-terminating therapies.
Conclusion: This small IVF cohort had a much higher incidence of VE and MVP compared to the general population (background rates of <5 PVC/hr and 1–2.5% incidence of MVP), and the morphology of ectopy was unique. Although innocuous at large, this suggests that there may be a small subset of patients with a malignant phenotype comprised of female gender, mitral valve prolapse, and frequent ventricular ectopy with tightly-coupled PVCs of alternating morphologies. Determining precisely the sudden death predisposing risk factors among women with MVP and ventricular ectopy will require careful scrutiny.