In high-risk post-myocardial infarction (MI) patients with cardiac autonomic dysfunction and moderately reduced left ventricular ejection fraction (LVEF), remote monitoring of implantable cardiac monitors (ICM) was effective in early detection of serious arrhythmic events, according to findings from the SMART-MI-DZHK9 study presented during ESC Congress 2021.

Researchers randomized 400 high-risk patients from 33 centers in Germany and Austria to ICM implantation and remote monitoring, or conventional follow-up. All patients were survivors of acute MI and were in sinus rhythm with an LVEF of </≥ 45%. Median age was 60 years and 20% were female. The primary endpoint was time to detection of serious arrhythmic events. Median follow-up was 21 months, during which 11 patients in the ICM group died compared with 9 patients in the control group.

Overall results showed the primary endpoint occurred in 29.9% (n=60) of patients in the ICM group and 6% (n=12) in the control group. Researchers observed an improved detection for all types of serious arrhythmic events in the ICM group, including atrial fibrillation, higher degree atrioventricular block, fast non-sustained ventricular tachycardia and sustained ventricular tachycardia/ventricular fibrillation. Additionally, ICM-based detection of serious arrhythmic events was associated with a 6.82-fold increased risk for subsequent major adverse cardiac and cerebrovascular events, the researchers said.

"The study found that post-infarction patients with cardiac autonomic dysfunction and only moderately reduced LVEF developed a high number of serious subclinical arrhythmic events that could be detected early and effectively with ICMs," said Axel Bauer, MD, principal investigator of the study. "The spectrum and frequency of arrhythmias in these patients was comparable to that of post-infarction patients with reduced LVEF, who are currently candidates for prophylactic ICD therapy. Our study supports the use of ICMs in high-risk post-MI patients with moderately reduced LVEF and cardiac autonomic dysfunction as a sensitive tool for continuous risk assessment."

The study is limited in that it was a diagnostic study with a small sample size and short follow-up period and thus not powered to detect differences in clinical outcomes. Future studies should look at whether early detection of – and response to – serious arrhythmic events can lead to better outcomes.

Clinical Topics: Acute Coronary Syndromes, Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure

Keywords: ESC Congress, ESC21, Stroke Volume, Ventricular Function, Left, Arrhythmias, Cardiac, Electrocardiography, Infarction, Acute Coronary Syndrome, Heart Failure, ACC International

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