Abstract 14340: Premonitory Supraventricular Arrhythmas Triggering Ventricular Arrhythmias in Patients with Hypertrophic Cardiomyopathy and ICDs: Implications for Preventive Therapy
Introduction. Patients with hypertrophic cardiomyopathy (HCM) are at risk for ventricular arrhythmias and sudden cardiac death. However, the initiation and morphology of the ventricular arrhythmias that trigger such events are poorly characterized. ICDs store the intracardiac electrogram of patients and we hypothesize that understanding the mechanisms by which lethal ventricular tachyarrhythmias occur in HCM has potential importance in preventing sudden death and appropriate ICD interventions
Methods. Intracardiac electrograms from 81 patients with ICDs and ventricular arrhythmias were analyzed independently by 3 individuals and differences in interpretation were resolved by consensus. Sustained VF was defined as a ventricular arrhythmia with ventricular rates > 220 beats/min (cycle length < 272 ms) in which intracardiac morphology varied from beat to beat and required an ICD defibrillation to terminate. VT was defined as a monomorphic and regular ventricular tachycardia, and VFL was defined as VT with a cl < 260 ms.
Results. Of 149 ventricular arrhythmias, monomorphic VT was present in 75 (17 with cl < 260 ms) and VF in 74. Rhythms preceding the ventricular tachyarrhythmias were often sinus tachycardia (49/149; 33%) or less commonly rapid atrial fibrillation (7/149; 5%). In particular, VF and VFL were more likely to have been preceded by sinus tachycardia or rapid atrial fibrillation (30 of the 68 with VF; 44%; 10 of the 14 with VFL 71%, compared to 16 of the 52 with slower VT 30%; p=.02). Pauses of > 1 s in the beats preceding the initiation were more common in VF (9/65) as compared to VT (2/66).
Conclusions. Monomorphic VT is as common in high risk patients with HCM as is VF. Rapid atrial arrhythmias frequently precede the onset of VF and VFL. These rapid sinus and atrial arrhythmias are likely adrenergically mediated and could be blunted by beta-blockade.
- © 2012 by American Heart Association, Inc.