Implanted Cardiac Monitor Reduced Treatment Delay in Acute Coronary Syndrome

Heart rate monitor in an intensive care unit.
Heart rate monitor in an intensive care unit.
Compared with current standard of care, implantation of a device for intracardiac ST-segment monitoring and alerting in people who are at high risk for recurrent ACS resulted in a significant decrease in median pre-hospital delay.

For patients at risk for adjudicated acute coronary syndrome events, intracardiac monitoring with real-time alarms reduced the delay in getting to the hospital, according to a study published in the Journal of the American College of Cardiology.

The aim of this study was to assess the effect of the intracardiac monitoring and alerting system (AngelMed Guardian System) on delays in getting to the hospital after an acute coronary syndrome event. Data for this analysis came from the randomized, prospective phase 3 AngelMed for Early Recognition and Treatment of STEMI (ALERTS; identifier: NCT00781118) trial. The ALERTS trial consisted of 907 patients at risk for coronary artery disease who successfully had the AngelMed Guardian System monitor implanted. Patients were then randomly assigned into either an alarm-on cohort or an alarm-off cohort. This portion of the trial lasted for 6 months; thereafter, all alarms were turned on for the last 6 months of the study. The ALERT system would signal the patient in real-time if their ST-segment deviated from the normal rhythm. The outcome of interest was the time from the ALERT system signal or identification of symptoms to arrival at the emergency department doors.

Of the 907 patients included in this study, there were 181 emergency department visits in the alarm-off cohort and 970 emergency department visits for the alarm-on cohort. In the alarm-off cohort, 18% were an adjudicated acute coronary syndrome event, and the median time to emergency department was 8.0 hours.

In the alarm-on cohort, 20% were an adjudicated acute coronary syndrome event; 46% of these were prompted by an ALERT system signal (54% of these were prompted by symptoms only), and the median time to emergency department was 1.7 hours (P <.0001). When both symptoms and alarms were present, alarms preceded symptoms 52% of the time.

If using ≤2 hours from signal to the emergency room as a cut-off, 10% of the alarm-off cohort arrived in that time frame and 55% of the alarm-on cohort arrived in that time frame. When just assessing myocardial infarctions (MI), 88% of patients with an alarm and symptoms arrived ≤2 hours and 77% of patients with an alarm only arrived ≤2 hours.

In the alarm-off cohort, the median time for arrival for an MI was 12.7 hours, and in the alarm-on cohort, the median time for arrival for an MI was 1.6 hours (P <.0089).

This study is limited, so future studies need to evaluate the reasons behind false-positive and false-negative scenarios and assess the clinical implication of earlier treatment due to the ALERT system signal.

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The researchers concluded “[a]n implantable cardiac monitor that alerts patients with [coronary artery disease] to rapidly progressive, abnormal ST-segment deviation can reduce delayed arrival in the [emergency department] for management of acute MI.”

Disclosure: This clinical trial was supported by Angel Medical Systems. Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Holmes DR Jr, Krucoff MW, Mullin C, et al. Implanted monitor alerting to reduce treatment delay in patients with acute coronary syndrome events. J Am Coll Cardiol. 2019;74(16):2047-2055.