COVID Shot After Acute Coronary Syndrome Might Not Prevent Further Events

Vaccination for COVID-19 after an acute coronary syndrome (ACS) event was not associated with better cardiopulmonary outcomes or fewer major adverse cardiovascular events, according to a secondary analysis of the Brazilian VIP-ACS trial.

Censoring the first 90 days post-vaccination in this non-randomized comparison, people with ACS who had received at least one COVID-19 vaccine dose had 4.81 cardiopulmonary events per 100 patient-years as compared with 9.37 among those not vaccinated, Henrique Fonseca, PhD, of the Hospital Israelita Albert Einstein in São Paulo, and colleagues reported in JAMA Network Open.

Despite the numerical difference in cardiopulmonary events between the two groups, the result did not reach statistical significance after adjustment for multiple comparison (P=0.12). Cardiopulmonary events included all-cause death, myocardial infarction (MI), stroke, urgent coronary revascularization, as well as hospitalization for unstable angina, heart failure, or respiratory infection.

Vaccination — which was mostly with AstraZeneca’s COVID shot, a vaccine never authorized in the U.S. — also did not significantly reduce the secondary endpoint of major adverse cardiovascular events (MACE; P=0.60). There were 4.32 such cardiovascular death, MI, or stroke events per 100 patient-years in the unvaccinated group versus 1.19 events in the vaccinated group.

These prospective findings counter recent retrospective studies demonstrating a short-term reduction in MACE risk after COVID-19 vaccination, Fonseca and colleagues noted.

While an interesting study, it had some important limitations, commented Susan Cheng, MD, a cardiologist at Cedars-Sinai Medical Center in Los Angeles, who was not involved in the study. “It appears they conducted the study relatively early on in the pandemic in a relatively high-CV-risk group of people,” she told MedPage Today. “So it may be hard to generalize results to a broader population and to where we are now in the post-pandemic or endemic era.”

The study was also relatively underpowered, Cheng pointed out. “This is probably a key issue,” she said, noting that there was at least some separation of the 360-day Kaplan-Meier event curves between the vaccinated and unvaccinated individuals, but the total sample size and number of events was quite small in the vaccinated group.

“As a clinician, I would say the results are interesting, although [they] would not change my practice of advising patients who have a high risk for cardiopulmonary events to obtain a COVID vaccination if they have not been recently infected with COVID,” she added.

The primary aim of the multicenter VIP-ACS trial was to investigate whether double-dose influenza vaccination during hospitalization for ACS would further reduce the risk of major cardiopulmonary events when compared with guideline-recommended standard-dose influenza vaccination. That randomized comparison — conducted from July 19, 2019, and Nov. 30, 2020, at 25 centers in Brazil — concluded that this strategy did not improve cardiopulmonary outcomes compared with standard-dose vaccination.

The prespecified secondary analysis examined COVID-19 vaccination, which was not randomly assigned. During the first 90 days after an ACS event, a total of 1,665 of the 1,801 trial participants did not experience a cardiopulmonary event and were included in the landmark analysis, which was designed to minimize ascertainment immortal bias.

Patients were followed to 360 days. About 30% were female, and the median age was 56.7 years. Approximately 16% had had prior myocardial infarction, and 36% were current smokers.

About half of the secondary analysis patients had received at least one COVID-19 vaccine dose, and at least one dose was the AstraZeneca ChAdOx1 shot for about 64% of these participants. That vaccine first became available in Brazil in early 2021. Other vaccines that were available in Brazil were the Chinese developed-Sinovac vaccine, Pfizer’s BNT162b2 mRNA shot (Comirnaty), and Johnson & Johnson’s Ad.26.COV2.S vaccine, which is no longer available in the U.S.

“Our results should not be generalized to other COVID-19 vaccines,” the researchers cautioned.