WASHINGTON — Although monitoring for arrhythmias in high-risk patients following myocardial infarction (MI) frequently detects rhythm events requiring treatment within 2 years, treatment has not led to better outcomes, according to the BIO|GUARD-MI study.
Among patients who had a cardiac monitoring device implanted, 39% had arrhythmias requiring treatment, compared to 6% of control patients, but treatment did not result in absence of the primary endpoint of mortality cardiovascular disease or hospitalization for arrhythmia, acute coronary syndrome, worsening of heart failure, stroke, systemic embolism or major bleeding (HR 0.84, 95% CI 0, 64-1.10, P=0.21), reported Christian Jons, PhD, of Rigshospitalet Copenhagen in Denmark, at the American College of Cardiology (ACC) meeting.
“Part of the reason the BIO-GUARD study didn’t have a positive result may simply be that disease-modifying therapy has gotten so good,” ACC President Edward Fry said. MD, of Ascension’s St. Vincent Medical Group in Indianapolis.
“As medical treatment improves more and more with universal treatment with beta-blockers, spirolactones, early institution of sacubitril/valsartan, and now that we have SGLT2 inhibitors, it becomes more difficult for another treatment to modify the result to show a benefit,” he said. Recount MedPage Today, noting that other major non-medical barriers to wider use of implanted cardiac monitoring include cost and reimbursement issues.
Although there were mostly no significant differences between the predefined subgroups, patients who had ST-segment elevation myocardial infarction (NSTEMI) had fewer primary endpoint events. with monitoring versus no monitoring (HR 0.69, 95% CI 0.49-0.98). This was not the case for patients with STEMI (HR 1.10, 95% CI 0.72-1.69; P=0.09).
“In the predefined subgroup of NSTEMI patients, the primary endpoints were reduced by 31%,” Jons noted. “This benefit appears to be associated with a higher risk in NSTEMI patients.”
Noting the difference in outcomes between patients with STEMI and those with NSTEMI, discussant Roxana Mehran, MD, of Mount Sinai Hospital in New York City, told Jons that she hoped he would validate this important endpoint. . “Because your study ended prematurely, the number of events for the primary endpoint did not reach what was needed and what you originally sampled.”
The BIO-GUARD-MI study was designed to assess 372 primary endpoint events, but was plagued with reporting inconsistencies. These inconsistencies were observed in the first interim analysis, and the decision was made to truncate the trial to address reporting issues and inherent reporting bias. At that time, 218 patients had experienced an event related to the primary endpoint.
The study included 790 patients considered high risk by their CHA2DS2-VASc score after MI, with a score ≥4 for men and ≥5 for women making them eligible for the trial. Patients with a history of atrial fibrillation were excluded from the study.
Of the 398 participants randomized to surveillance with an implanted device, the mean age was 72 years, 73% were male, 60% had a history of diabetes, and 17% had more than one MI. Of the 392 randomized to the control group, the mean age was 71, 71% were male, 62% had a history of diabetes, and 18% had more than one MI.
Of the patients requiring treatment, about 40% were treated with oral anticoagulants, about 20% received pacemakers, and about 8% received antiarrhythmic drugs.
Jons revealed relationships with BIOTRONIK and Abbott.
Mehran disclosed relationships with Sanofi/Bristol Myers Squibb, AstraZeneca, Cardiva, Cordis, the Medicines Company and Regado Biosciences.