Implantable Cardiac Alert System for Early Recognition of ST-Segment Elevation Myocardial Infarction

Abstract

Background: Symptoms remain a poor prompt for acute coronary syndromes (ACS). Timely restoration of perfusion in ST-segment elevation myocardial infarction is associated with improved left ventricular function and survival.

Objectives: This report details the results of ALERTS (AngelMed for Early Recognition and Treatment of STEMI), a multicenter, randomized trial of an implantable cardiac monitor that alerts patients with rapidly progressive ST-segment deviation.

Methods: High-risk ACS subjects (N = 907) were randomized to a control (alarms deactivated) or treatment group for 6 months, after which alarms were activated in all subjects. The primary safety endpoint was absence of system-related complications (>90%). The composite primary efficacy endpoint was cardiac/unexplained death, new Q-wave myocardial infarction, or detection to presentation time >2 h.

Results: Safety was met with 96.7% freedom from system-related complications (n = 30). The efficacy endpoint for a confirmed occlusive event within 7 days was not significantly reduced in the treatment compared with control group (16 of 423 [3.8%] vs. 21 of 428 [4.9%], posterior probability = 0.786). Within a 90-day window, alarms significantly decreased detection to arrival time at a medical facility (51 min vs. 30.6 h; Pr [pt < pc] >0.999). In an expanded analysis using data after the randomized period, positive predictive value was higher (25.8% vs. 18.2%) and false positive rate significantly lower in the ALARMS ON group (0.164 vs. 0.678 false positives per patient-year; p < 0.001).

Conclusions: The implantable cardiac system detects early ST-segment deviation and alerts patients of a potential occlusive event. Although the trial did not meet its pre-specified primary efficacy endpoint, results suggest that the device may be beneficial among high-risk subjects in potentially identifying asymptomatic events. (AngelMed for Early Recognition and Treatment of STEMI [ALERTS]; NCT00781118).

Keywords: ST-segment elevation myocardial infarction; acute coronary syndrome; implantable monitoring device; symptom-to-door time.