Aims: Higher mortality rates after coronary artery bypass grafting (CABG) have been reported in women than in men. We examined whether adherence to secondary prevention medications could explain these sex differences.

Methods: We used data from 9,857 participants (18% women) who underwent CABG between 1998 and 2021. Medication adherence for statins, beta blockers, and renin-angiotensin-aldosterone system (RAAS) inhibitors was assessed using nationwide drug purchase registers. Multivariable-adjusted Cox regression models with a sex interaction term were used to analyze the association between adherence and all-cause mortality.

Results: Use of statins (90%), RAAS inhibitors (62%), and beta blockers (93%) was similar in men and women immediately after CABG (P≥0.57 for all). After 10 years, adherence remained high for statins (84%), beta blockers (85%), and RAAS inhibitors (66%), with a non-significant trend towards greater adherence in women. Use of medications was associated with lower mortality in men and women, and particularly for statins (HR, 0.49; 95% confidence interval [CI], 0.41-0.59 for women; HR, 0.54; 95% CI, 0.50-0.59 for men; p for interaction 0.08). Beta blocker adherence was associated with a greater mortality benefit in women compared to men (HR, 0.66; 95% CI 0.55-0.78 versus HR, 0.82; 95% CI, 0.75-0.90; p for interaction 0.04).

Conclusions: No major sex differences in medication adherence were observed during 10 years of follow-up. Use of beta blockers was associated with lower risk of mortality in women compared with men. Future interventional trials should focus on the potential sex differences in efficacy of secondary prevention medication in CABG patients.