Cardiovascular Research Technologies
Cardiovascular Research Technologies
March 08, 2019
2 min read

Implantable cardiac alert system may benefit patients at high risk for ACS

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C. Michael Gibson
C. Michael Gibson

WASHINGTON — An implantable cardiac monitoring system failed to meet its primary efficacy endpoint, but showed promise in an expanded analysis for identifying occlusive coronary events in patients at high risk for ACS, according to data from the ALERTS trial.

The randomized controlled trial, presented at Cardiovascular Research Technologies by C. Michael Gibson, MS, MD, professor of medicine at Harvard Medical School, interventional cardiologist at Beth Israel Deaconess Medical Center and director of Baim/PERFUSE Research Institutes, and published in the Journal of the American College of Cardiology, evaluated an implantable cardiac monitoring and alerting system (AngelMed Guardian, Angel Medical Systems) designed for early detection of ST changes in patients at high risk for ACS or MI.

All 907 patients enrolled in the study were implanted with the system and randomly assigned to the treatment (active alerts) or control group (disabled alerts).

The primary safety endpoint was the absence of system-related complications requiring a system revision or invasive intervention to resolve in at least 90% of patients through 6-month follow-up, the researchers wrote, and the primary efficacy endpoint was a composite of cardiac or unexplained death, new Q-wave MI or detection-to-presentation time longer than 2 hours for a documented coronary occlusion event. The mean follow-up was 3.05 years.

The rate of freedom from system-related complications was 96.7% (posterior probability > 0.999). Infection (1.2%), persistent pain at the incision site (0.3%), erosion (0.2%), device malfunction (0.2%), perforation (0.1%) and cosmetic issues (0.1%) were all cited as causes for system removal. No complications led to permanent morbidity or disability.

At 7 days, there was no reduction in the primary efficacy endpoint in the treatment vs. control groups (3.8% vs. 4.9%; posterior probability = 0.786), nor were there any significant reductions during other time windows. However, there was a trend toward significance at 90 days (3.8% vs. 6.8%; posterior probability = 0.974).

Detection-to-presentation time at 7 days was 51 minutes in the treatment group, as compared with 30.6 hours in the control group (posterior probability > 0.999). At 90 days, detection-to-presentation time remained the same in the treatment group, but increased to 22 days in the control group (posterior probability > 0.999). The time from detection to hospital arrival for a confirmed coronary occlusion occurred within 2 hours in 85% of the treatment group vs. 5% of the control group.

In an expanded analysis that included data from patients in the control arm who had their alarms activated after 6 months, the positive predictive value of alerts was 25.8% in patients with or without symptoms whose alarms were on vs. 18.2% in patients with symptoms whose alarms were off. Additionally, 42 silent MIs were detected in patients whose alarms were on that would not have been detected in those whose alarms were off.


Notably, the false-positive rate was also lower in patients with alarms on than those with alarms off (0.164 vs. 0.678 false positives per patient-year; P < .001).

“Overall, the implantable cardiac system was safe, and the rate of complication was low. However, the ALERTS trial failed to meet the prespecified primary efficacy endpoint of the randomized trial. Nonetheless, in an expanded analysis including data both during and after the randomized portion of the trial, the positive predictive value was higher and the false-positive rate was lower among the ALARMS ON group. These findings suggest the system may be beneficial in the identification of symptomatic and asymptomatic occlusive coronary events among high-risk ACS subjects,” Gibson and colleagues wrote in the JACC publication. – by Melissa Foster


Gibson CM, et al. Late-Breaking Trials: Session I. Presented at: Cardiovascular Research Technologies; March 2-5, 2019; Washington, D.C.

Gibson CM, et al. J Am Coll Cardiol. 2019;doi:10.1016/j.jacc.2019.01.014.

Disclosures: The study was funded by Angel Medical Systems. All authors report they received research grant support from Angel Medical Systems.