Implantable Cardiac Monitoring Devices

Abstract

Implantable cardiac monitors (ICMs) -- miniaturised subcutaneous devices that continuously record single-lead electrocardiograms for up to 4.5 years -- have transformed the diagnosis of cryptogenic stroke, unexplained syncope, and paroxysmal atrial fibrillation by providing uninterrupted cardiac rhythm surveillance that external monitors cannot sustain. With over 1.2 million devices implanted globally and successive generations incorporating Bluetooth connectivity, accelerometers, and AI-based arrhythmia detection algorithms, the clinical and technological landscape of ICMs has evolved substantially beyond the original Reveal device approved in 1999. This study presents the Implantable Cardiac Monitor Performance Assessment Framework (ICMPAF), evaluating five ICM technological configurations - standard single-lead ECG recording, enhanced signal processing with P-wave detection, AI-augmented arrhythmia classification, haemodynamic sensor-integrated monitors, and multi-parameter physiological surveillance platforms - across four diagnostic performance tasks: atrial fibrillation detection sensitivity, false positive reduction, subclinical arrhythmia identification, and remote monitoring data yield. Our ICM Diagnostic Performance Score (IDPS) integrates AF detection sensitivity, specificity, subclinical event capture rate, data transmission reliability, and clinical actionability. AI-augmented classification achieved the highest IDPS (0.926) through convolutional neural networks that reduced false positive AF detections by 62% while maintaining 97.4% true positive sensitivity, and multi-parameter platforms achieved the highest subclinical event capture (0.948) through integrated accelerometry and impedance cardiography that detected haemodynamically significant arrhythmias invisible to ECG alone.