Patients who undergo percutaneous coronary intervention following non-ST-elevation myocardial infarction are more likely to receive guideline-recommended secondary prevention drugs than those who receive coronary artery bypass grafts, an Australian study suggests.
Writing in Heart, Lung and Circulation [link here], researchers say interventions are needed to address possible clinician and patient uncertainty about the benefits of certain preventive drugs, regardless of revascularisation strategy.
Their study involved drawing data from 15,399 non-ST-elevation MI (NSTEMI) admissions to public and private hospitals, which involved 14,557 patients (76% male) aged 30 and older from Victoria between July 2012 and June 2017.
Of these admissions, 11,754 (76%) received percutaneous coronary intervention (PCI) only and 3,645 (24%) received coronary artery bypass grafts (CABG) or both interventions, either during the admission or within 30 days of discharge.
Only 0.73% of admissions involved both procedures within the timeframe.
Both groups had similar age and sex characteristics, although comorbidities were more prevalent among the patients undergoing CABG, while rates of prior revascularisation were higher among patients receiving PCI.
Findings showed initial dispensing of secondary prevention medications differed between the two revascularisation strategies in the 60 days following discharge.
While only a small proportion of patients received no medications (PCI 5% vs CABG 6%), dispensing of all four drug classes was more common among patients undergoing PCI compared with CABG (49% vs 7% of admissions).
This was largely attributable to lower P2Y12 inhibitor use in the CABG group, said the researchers led by Monash University, Melbourne.
The researchers predicted the probability of initial dispensing for the different drug classes in the 60 days following discharge for the PCI and CABG groups:
- P2Y12 inhibitor: 0.94 vs 0.17
- ACEi/ARB: 0.69 vs 0.42
- Beta blockers: 0.59 vs 0.69
- Statins: 0.89 vs 0.89
- High intensity statins: 0.60 vs 0.69
P2Y12 inhibitors showed the largest difference between PCI and CABG, whereas statin therapy overall showed no difference in dispensing probability. The use of high intensity statin therapy was more prevalent in people receiving CABG.
There were also lower rates of ACEi/ARB dispensing in the CABG group than in the PCI group, despite these patients having a higher prevalence of comorbidities where the drugs were more likely to have greater benefit, the researchers said.
Results were similar regardless of whether the patient had no prior MI or revascularisation, revascularisation during admission or within the next 90 days.
Patterns for the proportion of days covered in the 12 months from discharge were similar to initial dispensing patterns in the PCI and CABG groups:
- P2Y12 inhibitor: 0.82 vs 0.12
- ACEi/ARB: 0.62 vs 0.43
- Beta blockers: 0.53 vs 0.62
- Statins: 0.79 vs 0.78
- High intensity statins: 0.49 vs 0.55
The researchers said, to their knowledge, this was the first Australian study on post-discharge medication use following NSTEMI in people with different revascularisation strategies using dispensing data.
“This difference may arise because post-discharge prescribing decisions are made by different treating teams according to the revascularisation strategy, suggesting that in-hospital cardiology and cardiothoracic surgery teams may prescribe differently,” they said.
The reasons for variation in P2Y12 inhibitor use were likely to be multifactorial and might be related to a less robust evidence base among post-CABG patients, they added.
“While patients with NSTEMI undergoing PCI require [P2Y12 inhibitor] initiation before or at the time of PCI, post-CABG use requires additional steps,” they wrote.
“P2Y12i are either withheld or discontinued five days before CABG and thus recommencement (or most often commencement) postoperatively may occur sometime after the original admission where ischaemic risk may be less explicitly appreciated compared with concerns about bleeding risk, which likely dominate.”
They referred to a meta-analysis on P2Y12 inhibitor use in patients receiving CABG published at the time the cohort was undergoing revascularisation, which showed a relative reduction in 30-day mortality of 0.62, but an increase in major bleeding.
However, there was a rise in P2Y12 inhibitor use over the study period for CABG, suggesting “increasing adoption of guideline recommendations and an evolving evidence base”, with a predicted probability of 0.06 to 0.23 in first to final year.
They concluded that initiatives to promote the uptake of secondary prevention medications in the post-discharge period might be of particular benefit with respect to improving the use of ACEi/ARB and P2Y12 inhibitor among post-CABG patients.
Some authors have previously received payment from pharmaceutical companies.