Time course of appropriate implantable cardioverter-defibrillator therapy and implications for guideline-based driving restrictions

Background American Heart Association/Heart Rhythm Society recommendations restrict driving in implantable cardioverter-defibrillator patients for 6 months after implant for secondary prevention or primary prevention with an appropriate therapy (antitachycardia pacing or shock) for ventricular arrhythmias (VA). Objective The purpose of this study was to analyze implantable cardioverter-defibrillator therapy data to inform guideline recommendations on driving. Methods The OMNI Registry was queried for VA and assessed for the time course of appropriate therapies. A blind events committee adjudicated events. The Kaplan-Meier method was used to estimate event rates. A 7-day blanking period was used for each event of interest. Results A total of 2262 patients (mean age 67 ± 12 years; mean left ventricular ejection fraction 28%) were enrolled; 1659 (73%) were men, and 1666 (74%) were implanted for primary prevention. Overall, 628 of 2255 patients (28%) received ≥1 appropriate therapy. The probability of receiving a subsequent appropriate therapy increased and occurred in a shorter time interval with each appropriate therapy. At 6 months, the likelihood of receiving a shock when the first VA was terminated by shock (30.0%) was 3 times the risk when the first VA was terminated by antitachycardia pacing (9.9%). Conclusion Each appropriate VA therapy is associated with an increased risk of a subsequent event that occurs, on average, in a time frame shorter than current guideline-based restrictions. A differential risk of shock is noted in those receiving antitachycardia pacing vs shock for the first appropriate VA. These findings may help to inform future clinical guideline and practice decisions related to driving.