Cardiac Deceleration Capacity Refines Sudden Cardiac Death Risk Stratification in Patients with Hypertrophic Cardiomyopathy for Primary Prevention.

BACKGROUND

Precise sudden cardiac death risk stratification in hypertrophic cardiomyopathy remains challenging. Parasympathetic dysfunction is closely related to malignant ventricular arrhythmias, and deceleration capacity is a robust parameter to quantify vagal tone. This study aims to elucidate the association between deceleration capacity and sudden cardiac death risk in hypertrophic cardiomyopathy.

METHODS

A total of 648 hypertrophic cardiomyopathy patients completing 24-hour ambulatory Holter monitoring were consecutively enrolled in this cohort study. Baseline deceleration capacity was calculated from the Holter recordings. The primary endpoint was a composite of sudden cardiac death or sudden-cardiac-death-equivalent events including sudden death, resuscitated cardiac arrest, and appropriate implantable cardioverter-defibrillator (ICD) therapies.

RESULTS

There were 464 patients included in final analysis. During mean follow-up of 827 days, 33 (7.1%) patients met primary composite endpoint. Deceleration capacity showed a significant linear inverse association with this composite endpoint (hazard ratio 0.660 [95% confidence interval, 0.546-0.799], P < 0.001). The derived cut-off value was 6.25 ms. Adding deceleration capacity to the traditional risk model significantly improved risk discrimination (C-statistic increased from 0.732 to 0.827, Delong P = 0.019) especially in the intermediate-risk subgroup (C-statistic increased from 0.565 to 0.849, Delong P = 0.011). Patients with lower deceleration capacity and elevated risk score suffered the worst outcome (Log-rank P < 0.001).

CONCLUSIONS

Deceleration capacity independently predicts sudden cardiac death risk in hypertrophic cardiomyopathy and provides significant prognostic value particularly in the clinically challenging intermediate-risk subgroup. Integration of deceleration capacity into risk evaluation warrants prospective validation before guiding ICD decision-making.