Introduction and methods

Secondary prevention medication after coronary artery bypass surgery and long-term mortality: A longitudinal population-based study from the SWEDEHEART registry

Presented at ESC Congress 2019 in Paris, France by Erik Björklund (Göteburg, Sweden)

CABG is recommended for selected patients with complex coronary artery disease (CAD). Secondary prevention is recommended to reduce risk for CAD progression and mortality, but reports have described low utilization. All cardiac surgery procedures since 1992 in Sweden are registered in the Swedish Cardiac Surgery registry, which is part of SWEDEHEART. Other nationwide mandatory registries cover dispensed medications, diagnosis on all hospital admissions and date and cause of death. The totality of data allows long-term follow-up of a nationwide cohort in a real-world setting.

The aim of this study was to describe the dispense of statins, β-blockers, RAAS inhibitors and platelet inhibitors after CABG in relation to age and sex as well as to investigate associations between longitudinal use of secondary prevention medications and long-term mortality. Baseline was considered 6 months after hospital discharge after CABG (in 2006-2015). Medication exposure status was updated every 3 months through follow-up. Follow-up ended at death or emigration or December 31, 2015.

Main results

• RAAS inhibitors were used the least. Platelet inhibitors, statins and beta-blockers were used more and to a similar extent. Use of all medications declined over time.
• Associations between medication use and mortality risk showed that statins (adjHR: 0.56, 95%CI: 0.52-0.60, P<0.001), RAAS inhibitors (adjHR: 0.78, 95%CI: 0.73-0.84, P<0.001) and platelet inhibitors (adj HR: 0.74, 95%CI: 0.69-0/81, P<0.001) significantly reduced mortality risk.
• Use of beta-blockers did not significantly affect mortality risk (adj HR: 0.97, 95%CI: 0.90-1.06, P=0.54).

Conclusions

The use of secondary prevention medication after CABG was high early after surgery, but decreased significantly over time. Continuous treatment with statins, RAAS-inhibitors and platelet inhibitors was individually associated with a significant reduction in mortality risk. Beta-blocker treatment was not associated with improved survival after CABG, thus these data do not support routine long-term use of beta-blockers after CABG.

These findings support recommendations in the guidelines for use of statins, RAAS inhibitors and platelet inhibitors after CABG and they underline the importance of continuous treatment.

As a message for lay persons, Björklund added that CABG is not the definite cure for CAD; it is better viewed as a chronic progressive disease that warrants continuous treatment with secondary prevention medications to enjoy long-term benefits of revascularization.

Discussion

During the press conference, Björklund shared that the beta-blocker results were most surprising, in light of LV function. But this may be the result of the very crude inclusion criterium. Plans are to dig deeper into this, as this was only a subanalysis.

The question was raised why the use of medication declined over time. Björklund answered that patients treated for secondary prevention purposes are not treated for symptoms. Thus they may have stopped taking medication when they feel alright. But as the condition is progressive, it is important to continue treatment.

- Our reporting is based on the information provided at the ESC congress -

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