In a recent study published in the European Heart Journal, Erik Björklund et al. found that the secondary prevention medications, such as statins and renin-angiotensin-aldosterone system (RAAS) inhibitors, and platelet inhibitors used after coronary artery bypass grafting (CABG) are essential while the use of B-blockers had no association with survival and is questionable.
The drugs for secondary prevention were recommended after CABG by the current guidelines that included statins and antiplatelet drugs to everyone with no contraindications, RAAS inhibitors to patients with reduced left ventricular ejection fraction (LVEF) and hypertension, and B-blockers to patients with previous myocardial infarction and/or reduced LVEF. There were not enough data available for checking the data for the association of these medications and mortality. Also, adherence to these medications was low. The study was done to determine the use of secondary prevention medications over time in CABG patients and to investigate associations between the longitudinal use of secondary prevention medications and long-term mortality in a large cohort of CABG patients.
The study is an observational population-based retrospective cohort study. The study population included all patients who underwent isolated first time CABG study over 18 years of age from the Swedish cardiac surgery registry called SWEDHEART registry and anyone who was not alive after 6 months of surgery was excluded. The data was extracted from the registry beginning 1 Jan 2006 to 31 Dec 2015. The continuous variables were analyzed as mean with standard deviation or median with range/interquartile range. The categorical variables were compared with Fischer’s exact test and Mantel-Haenszel X2 test. In a sensitivity analysis, the adjusted Cox proportional hazard model was applied to consecutive 1 year time periods. Forest plots were used for subgroup analyses among the time updates use of the medications and their association with mortality.
“In the present study, statins, β-blockers, and platelet inhibitors were dispensed to over 90% of the patients at baseline. Our findings indicate that all secondary prevention medications were underutilized in patients aged ≥75 years. There was overall no major and consistent differences in the use of secondary prevention medication in relation to gender were observed. However, in contrast to the strong and consistent associations between reduced mortality and the use of statins and platelet inhibitors, there was no significant association between β-blocker-use and mortality in the fully adjusted models. These findings call into question the routine use of β-blockers after CABG.” -Dr. Erik Björklund M.D.
Dr. Erik Björklund et al. found that in 28,812 patients that were followed up for a median of 4.9 years that consisted 80.4% men and 19.6% women, the dispensed prescriptions increased from 91.5 to 96.0% for statins, from 89% to 92.4% for B blockers, from 64.4 to 78.4% for RAAS inhibitors and decreased from 93.2 to 92.2% for platelet inhibitors. The crude mortality rates with adjustment to age, sex and patient characteristics and comorbidities at the baseline and also additionally adjusted for time-updated use of the other secondary prevention drugs, statins (HR 0.56, 95% CI 0.52–0.60; P < 0.001), RAAS inhibitors (HR 0.78, 95% CI 0.73–0.84; P < 0.001), and platelet inhibitors (HR 0.74, 95% CI 0.69–0.81; P < 0.001) were significantly associated with a lower mortality risk, whereas there was no significant association between the use of β-blockers and mortality risk (HR 0.97, 95% CI 0.90–1.06; P = 0.54).
The investigators noted that the use of secondary prevention medications after CABG in Sweden was high early after surgery; the use of all secondary prevention drugs investigated decreased over time after surgery and was lowest in elderly patients, and the use of statins, platelet inhibitors, and RAAS inhibitors was individually associated with significantly better long-term survival whereas there was no association between the use of β-blockers and survival. The study had some strengths being the large cohort study in the real-world setting, the complete follow up and time-updated data on prescriptions. There were limitations that included the difference in adherence to secondary prevention medications in Sweden and other parts of the world. The study had limited data on smoking and thus was included in the statistical methods used. Also, smokers have poor outcomes after CABG and lower adherence. In this retrospective study, there is a risk of selection bias and unaccounted confounders that were not adjusted in the models.