Ventricular Tachyarrhythmias in Patients With Hypertrophic Cardiomyopathy and Defibrillators: Triggers, Treatment,
Mark S Link1, Katy Bockstall2, Jonathan Weinstock3
1UT Southwestern Medical Center, Dallas, Texas, USA.
Insights
Physical activity and rapid heart rhythms frequently trigger ventricular arrhythmias in hypertrophic cardiomyopathy (HCM) patients. These arrhythmias often require multiple implantable cardioverter-defibrillator (ICD) shocks, highlighting the need for antitachycardia pacing (ATP) programming.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Ventricular arrhythmias (VAs) in hypertrophic cardiomyopathy (HCM) are a significant concern.
- Implantable cardioverter-defibrillators (ICDs) play a crucial role in managing these events.
- Understanding triggers and intervention patterns provides insight into VA mechanisms and treatment in HCM.
Purpose of the Study:
- To analyze triggers and implantable cardioverter-defibrillator (ICD) interventions for ventricular arrhythmias (VAs) in patients with hypertrophic cardiomyopathy (HCM).
- To identify factors associated with the occurrence and management of VAs in this population.
Main Methods:
- Analysis of intracardiac electrograms from 71 HCM patients across two studies (HCM I and II).
- Classification of arrhythmias into ventricular fibrillation (VF), monomorphic ventricular tachycardia (VT), and ventricular flutter (VFL).
- Ascertainment of physical activity and preceding rhythm for each arrhythmic event.
Main Results:
- Of 149 arrhythmias, 74 were VF, 57 VT, and 18 VFL. Moderate to intense physical activity preceded over 50% of tachycardias.
- Sinus tachycardia or rapid atrial fibrillation frequently preceded VAs.
- Ventricular flutter and ventricular fibrillation were more likely preceded by supraventricular rhythms >100 bpm compared to VT.
- Antitachycardia pacing (ATP) successfully terminated 74% of treated arrhythmias.
- Multiple ICD shocks were more frequently required for VFL (56%) than VF (14%) or VT (8%).
- Arrhythmias requiring multiple shocks were often preceded by sinus tachycardia and/or moderate/intense physical activity.
Conclusions:
- Rapid supraventricular rhythms and moderate to intense physical activity are frequent triggers for VT and VF in HCM patients.
- These VAs often necessitate multiple ICD shocks for termination.
- Antitachycardia pacing (ATP) is effective for terminating VT and VFL and should be programmed in all HCM patients with ICDs.
Introduction:
Triggers and ICD interventions of ventricular arrhythmias in patients with hypertrophic cardiomyopathy (HCM) offer insight into mechanisms and treatment.
Methods And Results:
Intracardiac ICD electrograms from 71 HCM patients in the HCM I and II studies were analyzed by three individuals. Rhythms were defined as VF (polymorphic ventricular arrhythmia), VT (monomorphic ventricular tachycardia), and ventricular flutter (VFL; VT ≥ 240 bpm). Physical activity and rhythm preceding the arrhythmia were ascertained. Of 149 arrhythmias, VF was present in 74, VT in 57, and VFL in 18. In those whose activity was known, moderate or intense physical activity was associated with over 50% of the tachycardias (57 of 111). Rhythms preceding ventricular arrhythmias were often sinus tachycardia (49 of 149; 33%) or rapid atrial fibrillation (7 of 149; 5%). VF and VFL were more likely preceded by supraventricular rhythms >100 bpm (30 of 68 with VF; 44%; 12 of 16 with VFL 75%, vs. 14 of 50 with VT 28%; P = 0.001). Antitachycardia pacing (ATP) was successful in 39 of 53 (74%). Multiple shocks were more often required to terminate VFL (10 of 18; 56%) compared to VF (10 of 72; 14%) and VT (2 of 25; 8%; P < 0.0001). Of arrhythmias requiring more than one shock to terminate, 16 of 22 were preceded by sinus tachycardia and/or moderate or extreme physical activity.
Conclusions:
Rapid supraventricular rhythms, and at least moderate activity, frequently precede VT and VF, and when they occur in these situations often require multiple ICD shocks to restore sinus rhythm. ATP is successful in terminating VT and VFL, and should be a programmed in all HCM patients with ICDs.
