Syncope and Risk of Sudden Death in Hypertrophic Cardiomyopathy

Abstract

Background-The prognostic significance of syncope has not been investigated systematically in hypertrophic cardiomyopathy, and treatment strategies have been based largely on intuition and experience. Methods and Results-We assessed the relationship between syncope and sudden death in 1511 consecutive patients with hypertrophic cardiomyopathy. Unexplained (nϭ153) or neurally mediated (nϭ52) syncope occurred in 205 patients (14%). Over a 5.6Ϯ5.2-year follow-up, 74 patients died suddenly. Relative risk of sudden death was 1.78 (95% confidence interval 0.88 to 3.51, Pϭ0.08) in patients with unexplained syncope and 0.91 (95% confidence interval 0.00 to 3.83, Pϭ1.0) in those with neurally mediated syncope compared with patients without syncope. In multivariable analysis, the temporal proximity of unexplained syncope to initial patient evaluation was independently associated with risk of sudden death (Pϭ0.006). Patients with unexplained syncope within 6 months before the initial evaluation showed a 5-fold increase in risk compared with patients without syncope (adjusted hazard ratio 4.89, 95% confidence interval 2.19 to 10.94), a relationship that was maintained throughout all age groups (Ͻ18, 18 to 39, and Ն40 years). Older patients (Ն40 years of age) with remote episodes of syncope (Ͼ5 years before initial evaluation) did not show an increased risk of sudden death (adjusted hazard ratio 0.38, 95% confidence interval 0.05 to 2.74). Conclusions-In the present large cohort of patients with hypertrophic cardiomyopathy, unexplained syncope was a risk factor for sudden death. Patients with syncopal events that occurred in close temporal proximity to the initial evaluation showed a substantially higher risk of sudden death than patients without syncope. Older patients with remote syncopal events did not show an increased risk.

Arrhythmogenic Phenotype in Dilated Cardiomyopathy: Natural History and Predictors of Life‐Threatening Arrhythmias

“…The definition of PVCs >1000/24 h and ventricular couplets were based on the experience with left‐dominant arrhythmogenic cardiomyopathy 1. In our inclusion criteria for AR‐DCM, as in previous studies on laminopathies,14 we included a history of syncope, an established risk factor for major arrhythmic events in ARVC30 and hypertrophic cardiomyopathy 31, 32…”

Association between non-coding polymorphisms of HOPX gene and syncope in hypertrophic cardiomyopathy

“…Although both C>T substitution and In/Del polymorphism did not lead change in protein sequence, they showed significant association with syncope, one of the risk factors for death in HCM (37). Association of syncope with heterozygosity, but not with a certain allele of these polymorphisms, suggests that the co-existance of different alleles at different transcripts may interfere the transcriptional or translational efficiency of the gene at RNA level.…”

Pediatric cardiomyopathies: A review of literature on clinical status and meta-analysis of diagnosis and clinical management methods

“…The clinical value of device therapy seems to reduce on the long-term. However, device therapy lacks clear guidelines in the management of cardiomyopathies in pediatric patients compared to adult patients [70,71].…”

“…However, there is little evidence or consensus in studies of the value of automatic cardioverter-defibrillation in pediatric cardiomyopathies [68,69]. Although unexplained syncope linked with an elevated risk of sudden cardiac death is an indication for ICD as a primary or secondary prophylaxis, it lacks clear guidelines for pediatric populations [70,71].…”