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Implantable Monitors for Early Detection of STEMI
Study Questions:
Does an implantable cardiac monitor allow for early recognition of ST-segment elevation myocardial infarction (STEMI)?
Methods:
The ALERTS (AngelMed for Early Recognition and Treatment of STEMI) was a multicenter randomized trial to evaluate the use of an implantable cardiac monitor, which alerted patients to rapid progressive ST-segment deviation. The study population included high-risk patients defined as adults with a history of high-risk acute coronary syndrome (ACS) or multivessel coronary artery bypass grafting within the past 6 months and who had ≥1 additional risk factor (diabetes mellitus, renal insufficiency, TIMI score ≥3). Exclusions were presence of atrial fibrillation, bundle branch block, left ventricular hypertrophy, prior hemorrhagic stroke or transient ischemic attack (in the prior 6 months), localized scar tissue, high thresholds at the lead site, or presence of an implantable cardioverter-defibrillator or pacemaker. Participants were randomized to implantable monitors, which had alarms activated or deactivated for 6 months. The composite primary efficacy endpoint was cardiac/unexplained death, new Q-wave MI, or detection to presentation time >2 hours. The primary safety endpoint was absence of system-related complications (>90%).
Results:
A total of 907 adults were included in the study, of which approximately 32% were male, and the majority were white (86-87%). The mean age was 59 years. Almost half of the population was diabetic and over 90% had hypertension. Approximately one quarter were current smokers. Most had had a prior history of revascularization or reperfusion. Safety was met with 96.7% freedom from system-related complications; infection rates were 1.2% (11/910). 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 minutes vs. 30.6 hours; 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). Alarms were associated with a lower rate of new-onset left ventricular ejection fraction (LVEF) <40% following a confirmed occlusive event (4% [1/25] vs. 35.7% [5/14]).
Conclusions:
The investigators concluded that the implantable cardiac system detects early ST-segment deviation and alerts patients of a potential occlusive event. Although the trial did not meet its prespecified primary efficacy endpoint, results suggest that the device may be beneficial among high-risk subjects in potentially identifying asymptomatic events.
Perspective:
This study adds to a growing trend in real-time monitoring of patients. Although the study did not meet the efficacy endpoint, the rates of ACS in this population were low. Findings from this study, including lower rates of false positives and lower rates of new-onset LVEF <40% with these alarms, support the need for further studies.
Clinical Topics: Acute Coronary Syndromes, Arrhythmias and Clinical EP, Cardiac Surgery, Cardiovascular Care Team, Invasive Cardiovascular Angiography and Intervention, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Cardiac Surgery and Arrhythmias, Interventions and ACS, Hypertension, Smoking
Keywords: Acute Coronary Syndrome, Coronary Artery Bypass, Death, Sudden, Cardiac, Defibrillators, Implantable, Diabetes Mellitus, Hypertension, Myocardial Infarction, Myocardial Revascularization, Myocardium, Primary Prevention, Renal Insufficiency, Risk Factors, Smoking, Stroke Volume
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