Worrying decline in medication use after heart surgery

Use of preventative medications is high early after heart surgery but decreases significantly over time, according to Swedish researchers — despite the fact that many of these medications are linked with lower mortality.

Coronary artery bypass grafting (CABG) is the preferred method of revascularisation in patients with complex multivessel coronary artery disease, with 2473 isolated CABG procedures added to Sweden’s SWEDEHEART cardiac registry in 2018. Since the indication for CABG is complex coronary artery disease, it is considered high-risk for future events.

European guidelines recommend statins and platelet inhibitors for all CABG patients without contraindications; RAAS inhibitors for those with left ventricular ejection fraction (LVEF) below 40%, hypertension or previous myocardial infarction; and (long-term) beta-blockers for patients with LVEF below 40% or previous myocardial infarction. Yet limited published data suggest that use of prevention medication after CABG is surprisingly low and markedly lower compared to patients treated with percutaneous coronary intervention.

Swedish researchers thus sought to examine the use of prevention medications after CABG over time and the association with mortality, which has previously been poorly described. The analysis included all 28,812 patients who underwent isolated first-time CABG in Sweden in 2006 to 2015 and were alive six months after hospital discharge, with data on mortality and dispensed prescriptions collected until the end of 2015. Patients were followed up for a median of five years.

After adjusting for age, sex, comorbidities and use of other prevention medications, statins, RAAS inhibitors and platelet inhibitors were significantly associated with 44%, 22% and 26% lower relative risks of mortality, respectively; no association was found between use of beta-blockers and risk of mortality. Furthermore, each additional year using statins, platelet inhibitors and RAAS inhibitors was linked with 10%, 7% and 2% lower relative risks of mortality, respectively.

But while patients’ use of prevention medication was high early after surgery, it decreased significantly over time. Statins were dispensed to 93.9% of patients six months after discharge from surgery and 77.3% eight years later. Corresponding figures for beta-blockers were 91% and 76.4%; RAAS inhibitors 72.9% and 65.9%; and platelet inhibitors 93% and 79.8%.

First author Dr Erik Bjoerklund, of the Sahlgrenska Academy, noted that the study did not distinguish between legitimate reasons for not using the drugs (ie, contraindications), doctors’ non-prescription and patient non-adherence. He said, “One reason behind the fall in medications over time could be that in Sweden many CABG patients are not routinely seen by cardiologists beyond six to 12 months after the operation. Another factor may be that CABG relieves symptoms, so patients feel healthy and their motivation to use multiple daily medications wanes over the years.”

Dr Bjoerklund added that all of the drugs were dispensed less often to patients aged 75 and older, speculating that such patients may have contraindications or there might be less focus on improving their long-term survival compared to younger patients. He noted, “The survival benefits we observed were across ages, so our study does not support treating patients over 75 differently to younger patients.”

Dr Bjoerklund concluded, “The study shows that continuous treatment with statins, RAAS inhibitors and platelet inhibitors is essential for long-term survival after coronary artery bypass grafting (CABG). The observed decrease in use of these medications over time after CABG is therefore alarming and poses an area for improvement.”

Image credit: ©stock.adobe.com/au/hankimage9