EvaLuation Using Cardiac Insertable Devices And TelephonE in Hypertrophic Cardiomyopathy (ELUCIDATE HCM): a prospective observational study on incidence of arrhythmias.

BACKGROUND: hypertrophic cardiomyopathy (HCM) is a heterogeneous disease associated with arrhythmias. Non-sustained ventricular tachycardia (NSVT) is a risk factor for sudden cardiac death and part of current risk stratification. Furthermore, atrial fibrillation (AF), which increases the risk of stroke, is believed to be common in HCM patients. Routine ambulatory monitoring captures the rhythm only periodically over 24 to 48 hours, thus, the true burden of arrhythmia is unknown. The insertable cardiac monitor (ICM) should help determine a more realistic arrhythmia assessment in HCM patients.

OBJECTIVE: The purpose of this study was to ascertain the incidence of NSVT, AF, and bradycardia in unselected HCM patients by use of an ICM.

METHODS: Thirty adults, mean age 49.9±12.3 years, 25 (83.3%) males were implanted with a Confirm Rx ICM. The monitoring application was installed on the patient's smartphone which allowed for patient activation in case of symptoms. The ICM was programmed as follows: VT ≥160 beats per minute (bpm) for ≥8 intervals, AF ≥2 minutes of duration, and bradycardia ≤40 bpm or pause ≥3.0 seconds.

RESULTS: The mean calculated 5-year risk was 2.3% and 29/30 of the patients had risk <4%. During follow-up, AF was found in 9 patients (30.0%). At least one episode of NSVT was detected in 7 patients (23.3%). In 13 patients (43.3%), sino-atrial block/sinus arrest/sinus bradycardia were seen. No arrhythmia was detected in 9 patients (30.0%).

CONCLUSION: In this first prospective study using an ICM, the arrhythmia burden in HCM patients yielded 30.0% AF and 23.3% NSVT. This article is protected by copyright. All rights reserved.