The influence of sleep duration on patients with coronary artery disease: a four-year observational study

Abstract

Background: Coronary artery disease (CAD) is highly prevalent and fatal worldwide. In China, particularly in the southwest region, the association between CAD and sleep duration remains insufficiently understood. This study aims to investigate outcomes among CAD patients with varying sleep duration.

Methods: In a Southwest Chinese cohort, patients with CAD were categorized into three sleep duration groups: <6 hours, 6-8 hours, and >8 hours. Over a four-year follow-up, the endpoint including new-onset myocardial infarction and CAD-related deaths was recorded. The Fine-Gray model was employed to evaluate the estimated marginal occurrence probability of the target event. Additionally, Kaplan-Meier estimation and Cox regression analysis were conducted to further investigate the association between sleep duration and outcomes.

Results: The study enrolled 816 residents with CAD, who had an average age of 69.2 ± 8.3 years old, of whom 40.2% were male. Across the three sleep duration groups (6-8h, <6h, and >8h), the hazard ratios (HRs) with 95% confidence interval for new-onset myocardial infarction were: 1.00 (reference), 2.67 (1.57-4.55) (P < 0.001), and 0.98 (0.30-3.21) (P=0.970). For CAD-related mortality, the HRs were: 1.00 (reference), 5.20 (2.53-10.68) (P < 0.001), and 5.02 (1.59-15.80) (P=0.006). This trend was consistently observed in both the Fine-Gray model and subgroup analyses.

Conclusions: Both short (<6 hours/day) and long (>8 hours/day) sleep duration were linked to an elevated risk of cardiac mortality among CAD patients in Southwest China. Short sleep duration was also found to be associated with high myocardial infarction risk.

Keywords: CAD-related mortality; Southwest China; coronary artery disease; myocardial infarction; sleep duration.

Figure 1

Flowchart of the study design.

Figure 2

The distribution of sleep duration among the general population (A) and the three groups (B).

Figure 3

Univariate competing risk analysis model for endpoint events among sleep duration groups. (A) Cumulative incidence of myocardial infarction in participants with sleep duration <6 h versus 6-8 h. (B) Cumulative incidence of myocardial infarction in participants with sleep duration >8 h versus 6-8 h. (C) Cumulative incidence of CAD-related death in participants with sleep duration <6 h versus 6-8 h. (D) Cumulative incidence of CAD-related death in participants with sleep duration >8 h versus 6-8 h. Cumulative incidence curves were generated using the Fine-Gray competing risk model. Solid lines represent the incidence of the target end event (myocardial infarction or CAD-related death), while dashed lines represent competing events. Hazard ratios (HRs) with 95% confidence intervals (CIs) and corresponding P-values are provided within each panel.

Figure 4

Kaplan-Meier analysis for endpoint events among sleep duration groups. (A) Incidence of myocardial infarction by sleep duration (<6 h, 6-8 h, >8 h). Short sleep (<6 h) was associated with significantly higher risk compared to 6-8 h (HR=2.46, 95% CI: 1.48-4.07, P < 0.001). No significant difference was found for >8 h (P=0.803). (B) Survival probability for CAD-related death by sleep duration. Short sleep (<6 h) showed the highest mortality risk (HR = 5.74, 95% CI: 2.94-11.22, P < 0.001), followed by >8 h (HR=3.20, 95% CI: 1.05-9.73, P=0.040). The black curve represents the group with 6-8 hours sleep, red curve represents the group with less than 6 hours sleep, and blue curve represents the group with more than 8 hours sleep.

Figure 5

The association between sleep duration with new-onset myocardial infarction (A) and CAD caused death (B) by multivariate analysis.