Heart Rate Surge Improves Cardiovascular Risk Stratification Beyond Hypoxic Burden in Sleep Apnea.

BACKGROUND

Obstructive sleep apnea (OSA) imposes cardiovascular stress through intermittent hypoxia and event-related responses. Whether heart rate surge adds prognostic information beyond hypoxic burden (HB) remains unclear.

OBJECTIVES

The authors aimed to evaluate heart rate surge for cardiovascular mortality and its incremental value beyond HB in OSA.

METHODS

We analyzed 4,790 participants from a community-based cohort with overnight polysomnography. Heart rate surge was defined as peak heart rate within the event-aligned window minus mean heart rate during the 60-second pre-event baseline. Associations with cardiovascular mortality were assessed using Cox models. Incremental prognostic value was evaluated by C-index, net reclassification improvement (NRI), and integrated discrimination improvement.

RESULTS

During a median follow-up of 11.6 years (IQR: 10.4-12.4), 334/4,790 participants (7.0%) died of cardiovascular causes. Heart rate surge was weakly correlated with HB (Spearman ρ = 0.08; 95% CI: 0.04-0.10). The highest vs lowest heart rate surge quintile was associated with higher cardiovascular mortality risk (HR: 3.00; 95% CI: 2.10-4.30; P < 0.001) and each 1-SD increment was associated with a 27% higher risk (HR: 1.27; 95% CI: 1.19-1.35). Participants with elevated HB and heart rate surge had the highest risk (HR: 2.65; 95% CI: 1.79-3.92). Adding heart rate surge increased the C-index from 0.77 (95% CI: 0.74-0.79) to 0.81 (95% CI: 0.79-0.83), with ΔC of 0.04 (95% CI: 0.03-0.06), continuous NRI of 0.62 (95% CI: 0.51-0.74), categorical NRI of 0.16 (95% CI: 0.09-0.24), and integrated discrimination improvement of 0.05 (95% CI: 0.04-0.06).

CONCLUSIONS

Heart rate surge was independently associated with cardiovascular mortality and improved risk stratification beyond HB in OSA.