Evolution of Devices to Prevent Sudden Cardiac Death: Contemporary Clinical Impacts

Implantable cardioverter defibrillators (ICDs) are recommended for primary and secondary prevention of sudden cardiac death and were first implanted more than 40 years ago. The addition of cardiac resynchronization improved outcomes in the heart failure population and is now an important part of optimized therapy for this population. In this review, we will address patient selection, risk stratification, and outcomes after ICD placement and technological improvements. Gender disparities in referral and outcomes will be discussed. Far from early technologies with limited pacing capabilities and no antitachycardia pacing (ATP), we have now moved to complex devices with the addition of ATP/ATP during charging, cardiac resynchronization therapy, remote monitoring, and improved battery longevity. The requirement for defibrillation testing at time of implantation has changed and in most implants are not required as part of new clinical guidelines. As the components most likely to fail are the leads, and many complications arise from the intravascular components, extravascular ICDs were developed, the subcutaneous ICD is now an option for many patients, and substernal devices are under clinical trials. Because shocks are associated with worse outcomes, optimized ICD programming is now recommended, with the benefit of reducing appropriate and inappropriate shocks with a decrease in mortality and no increase in the syncopal events. All these improvements will have a positive effect on patient outcomes and quality of life, and new technologies will be developed in the future.