Key result
NSVT and IVPG ≥30 mmHg linked to ~531% higher risk of SCD or ICD interventions in HCM.
Why the study?
Conventional sudden cardiac death risk factors in hypertrophic cardiomyopathy have low positive predictive values, prompting evaluation of whether an elevated intraventricular pressure gradient serves as an additional risk modifier.
Does an elevated intraventricular pressure gradient (≥ 30 mmHg) increase the risk of sudden cardiac death or appropriate ICD interventions in hypertrophic cardiomyopathy patients receiving ICDs for primary prevention?
Cohort (n=60)
No
Does an elevated intraventricular pressure gradient (≥ 30 mmHg) increase the risk of sudden cardiac death or appropriate ICD interventions in hypertrophic cardiomyopathy patients receiving ICDs for primary prevention?
In HCM patients with primary prevention ICDs, a baseline resting intraventricular pressure gradient ≥ 30 mmHg, especially combined with nonsustained ventricular tachycardia, is associated with an increased risk of sudden cardiac death or appropriate ICD therapy.
May refine SCD risk stratification in primary-prevention HCM; hypothesis-generating and should not yet change practice.
BACKGROUND: Conventional risk factors for sudden cardiac death (SCD) justify primary prevention through implantable cardioverter-defibrillator (ICD) implantation in hypertrophic cardiomyopathy (HCM) patients. However, the positive predictive values for these conventional SCD risk factors are low. Left ventricular outflow tract obstruction (LVOTO) and midventricular obstruction (MVO) are potential risk modifiers for SCD. The aims of this study were to evaluate whether an elevated intraventricular pressure gradient (IVPG), including LVOTO or MVO, is a potential risk modifier for SCD and ventricular arrhythmias requiring ICD interventions in addition to the conventional risk factors among HCM patients receiving ICDs for primary prevention. METHODS: We retrospectively studied 60 HCM patients who received ICDs for primary prevention. An elevated IVPG was defined as a peak instantaneous gradient ≥ 30 mmHg at rest, as detected by continuous-wave Doppler echocardiography. The main outcome was a composite of SCD and appropriate ICD interventions, which were defined as an antitachycardia pacing or shock therapy for ventricular tachycardia or fibrillation. The Cox proportional hazards model was used to assess the relationships between risk factors and the occurrence of SCD and appropriate ICD interventions. RESULTS: Thirty patients met the criteria of elevated IVPG (50%). During the median follow-up period of 66 months, 2 patients experienced SCD, and 10 patients received appropriate ICD interventions. Kaplan-Meier curves showed that the incidence of the main outcome was higher in patients with an IVPG ≥ 30 mmHg than in those without an IVPG ≥ 30 mmHg (log-rank P = 0.03). There were no differences in the main outcome between patients with LVOTO and patients with MVO. The combination of nonsustained ventricular tachycardia (NSVT) and IVPG ≥ 30 mmHg was found to significantly increase the risk of the main outcome (HR 6.31, 95% CI 1.36-29.25, P = 0.02). Five patients experienced ICD implant-related complications. CONCLUSIONS: Our findings showed that a baseline IVPG ≥ 30 mmHg was associated with an increased risk of experiencing SCD or appropriate ICD interventions among HCM patients who received ICDs for primary prevention. Combined with NSVT, which is a conventional risk factor, a baseline IVPG ≥ 30 mmHg may be a potential modifier of SCD risk in HCM patients.
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Yazaki et al. (2021) conducted a cohort in Hypertrophic cardiomyopathy receiving ICD for primary prevention (n=60). Nonsustained ventricular tachycardia (NSVT) and IVPG ≥ 30 mmHg vs. Without NSVT and IVPG ≥ 30 mmHg was evaluated on Composite of sudden cardiac death and appropriate ICD interventions (HR 6.31, 95% CI 1.36-29.25, p=0.02). The combination of nonsustained ventricular tachycardia and a baseline intraventricular pressure gradient ≥ 30 mmHg significantly increased the risk of sudden cardiac death or appropriate ICD interventions in HCM patients (HR 6.31).
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