Modern pacemakers: hope or hype?

In recent years, the role of implantable pacing devices has expanded beyond the arrhythmia horizon and contemporary pacemakers' attempt to meet the physiological needs of patients. Modern pacemakers' functions include various modes of dual-chamber pacing, rate-response algorithms with dual sensors for optimum physiological response, cardiac resynchronization therapy (CRT), arrhythmia-prevention algorithms, antitachycardia pacing, and hemodynamic monitoring. The automaticity features of pacemakers enable continuous or intermittent monitoring of various pacemaker parameters including battery voltage, pacing impedance, sensing levels, pacing thresholds, and daily activity log. Modern pacemakers offer "physiological pacing" algorithms that minimize ventricular pacing and reduce the incidence of atrial fibrillation significantly. Ventricular pacing in patients with intact atrioventricular (AV) conduction or intermittent advanced AV block should be minimized with a hope to reduce heart failure hospitalization and mortality. A reduction in all-cause mortality due to physiological pacing, except for the CRT, has yet to be demonstrated in a randomized trial. Overall, modern pacemakers have acceptable performances to fulfill the clinical needs and have a reasonable safety margin. Promising new technologies are currently under development and offer hope to patients who may one day derive both symptomatic and mortality benefit from these devices.

Evaluation of the Genetic Basis of Familial Aggregation of Pacemaker Implantation by a Large Next Generation Sequencing Panel.

BACKGROUND: The etiology of conduction disturbances necessitating permanent pacemaker (PPM) implantation is often unknown, although familial aggregation of PPM (faPPM) suggests a possible genetic basis. We developed a pan-cardiovascular next generation sequencing (NGS) panel to genetically characterize a selected cohort of faPPM. MATERIALS AND METHODS: We designed and validated a custom NGS panel targeting the coding and splicing regions of 246 genes with involvement in cardiac pathogenicity. We enrolled 112 PPM patients and selected nine (8%) with faPPM to be analyzed by NGS. RESULTS: Our NGS panel covers 95% of the intended target with an average of 229x read depth at a minimum of 15-fold depth, reaching a SNP true positive rate of 98%. The faPPM patients presented with isolated cardiac conduction disease (ICCD) or sick sinus syndrome (SSS) without overt structural heart disease or identifiable secondary etiology. Three patients (33.3%) had heterozygous deleterious variants previously reported in autosomal dominant cardiac diseases including CCD: LDB3 (p.D117N) and TRPM4 (p.G844D) variants in patient 4; TRPM4 (p.G844D) and ABCC9 (p.V734I) variants in patient 6; and SCN5A (p.T220I) and APOB (p.R3527Q) variants in patient 7. CONCLUSION: FaPPM occurred in 8% of our PPM clinic population. The employment of massive parallel sequencing for a large selected panel of cardiovascular genes identified a high percentage (33.3%) of the faPPM patients with deleterious variants previously reported in autosomal dominant cardiac diseases, suggesting that genetic variants may play a role in faPPM.

Disparity in utilization of implantable cardioverter-defibrillators in treatment of heart failure based on sex and race.

Evaluation of: Hernandez AF, Fonarow GC, Lang L et al.:Sex and racial differences in the use of implantable cardioverter-defibrillators among patients hospitalized with heart failure.JAMA298(13), 1525-1532 (2007) [1] . Disparity of utilization of proven therapies for treatment of cardiac disease according to gender and ethnicity has been well documented in various aspects of cardiac care. Implanted cardiac defibrillators (ICDs) are devices that have been proven to prevent sudden cardiac death. This retrospective study examined ICD use in heart-failure patients who had an indication for ICD implantation, from the "Get with the Guidelines" program. The patients were stratified by gender and ethnicity (Black vs White). The overall rate of utilization (or intention for utilization) of ICDs was 35%, while among women and Black people the rate was significantly lower, at 27 and 23%, respectively, with the lowest rate being for Black women (28%). These findings suggest a bias against implantation of such devices in women and Black people, which is not explained by clinical variables.