P6575Evaluation of arrhythmias using an insertable cardiac monitor in patients with hypertrophic cardiomyopathy

Abstract

Abstract Background Hypertrophic cardiomyopathy (HCM) is a heterogeneous disease associated with arrhythmias. Life-threatening ventricular tachycardia (VT) or fibrillation is the main cause of sudden cardiac death (SCD) in HCM, even though bradycardia does occur. An implantable cardioverter-defibrillator effectively prevents SCD. Non-sustained VT is a risk factor for SCD and part of current risk stratification. Furthermore, atrial fibrillation (AF) is believed to be common in HCM and increases the risk of stroke. Notably, novel oral anticoagulant (NOAC) is recommended in HCM with AF, even in the absence of other risk factors. Routinely, arrhythmias are evaluated by 24–48 hours of ambulatory monitoring occasionally. Thus, the true burden of arrhythmia is unknown but may be elucidated by an insertable cardiac monitor (ICM). Purpose The purpose of this study was to ascertain the incidence of NSVT, AF, and significant bradycardia in unselected HCM patients by use of an ICM. Methods In total, 30 adults with HCM had an ICM Confirm Rx implanted subcutaneously at the level of the fourth rib on the left side. None had a cardiac device implanted previously since they were considered to be at low risk for SCD according to ESC risk score. The application for monitoring was installed in the patients' phone which also allowed for patient activation in case of symptoms. The ICM was programmed as follows: VT ≥160 beats per minute (bpm) during ≥8 intervals, AF ≥2minute of duration, and bradycardia ≤40 bpm or pause ≥3.0 s. Clin Trial Reg: NCT03259113. Results In total, 29 patients, mean age 51.2±12.3 years, 24 (82.8%) males, completed the monitoring and 1 had the phone disconnected the vast majority of time and was excluded for analyses. During a follow-up of 14–18 months, 9 patients (31.0%) had AF and were started on NOAC and potential dose-adjustment of beta-blocker. One of these patients had syncope due to rapidly conducted AF. One of the patients with AF also had episodes of atrial flutter. At least one episode of NSVT was detected in 6 patients (20.7%). In 11 patients (37.9%), sino-atrial block/sinus arrest were seen, typically 30–40 bpm. In 9 patients (31.0%) no significant arrhythmia were detected. Conclusion In this first study of ICM in HCM, evaluation of arrhythmia burden in low risk patients with HCM, yielded 31.0% AF, 20.7% NSVT, and 37.9% sino-atrial block/arrest. Acknowledgement/Funding Abbott