The Necessity of an ICD-Therapy in Patients with Indications for Primary Prevention of Sudden Cardiac Death. One Center Experience.

Aim      Analysis of responses of cardioverter-defibrillators implanted in patients with cardiomyopathies (CMPs) of various origins and a high risk of sudden cardiac death (SCD) to assess the effectiveness of a modern strategy for primary prevention of SCD.Material and methods  In the Federal Center for High Medical Technologies in Kaliningrad from 2014 through 2018, implantable cardioverter-defibrillators (ICD) and cardiac resynchronization therapy defibrillators (CRT-D) were installed in 165 patients. Major indications for device implantation in these patients included left ventricular (LV) systolic dysfunction with ejection fraction (EF) ≤35 %; chronic heart failure (CHF) consistent with the New York Heart Association (NYHA) functional class (FC) II-III (IV for CRT-D) without previous episodes of life-threatening ventricular arrhythmias, circulatory arrest and resuscitation, which was consistent with the current international strategy for primary prevention of SCD. The study patients were divided into two groups based on the CMP origin; group 1 included 101 (61.2 %) patients with CMP of ischemic origin (ICMP) and group 2 consisted of 64 (38.8 %) patients with CMP of non-ischemic origin (NCMP). Information about arrhythmic episodes and device activation was retrieved from the device electronic memory during visits of patients to the clinic and was also transmitted to the clinic by a remote monitoring system. This information was studied and evaluated for the validity and effectiveness of the device triggering. If necessary, the parameters of detection and treatment were adjusted taking into account the obtained information. Information was analyzed and statistically processed with the SPSS Statistics 20.0 software.Results The patients were followed up for 28.3 ± 15.6 months, during which the devices delivered therapy to 55 (33.3%) patients of the entire group. In the ICMP group, the devices were activated in 44 (26.7 %) patients and in the NCMP group, the devices were activated in 11 (6.7 %) patients. In group 1 (ICMP), appropriate triggering was observed in 33 (20.0%) patients and inappropriate triggering was observed in 11 (6.7%) patients. In group 2 (NCMP), appropriate triggering was observed in 2 (1.2 %) patients and inappropriate triggering was observed in 9 (5.5 %) patients. The main cause of inappropriate triggering was atrial fibrillation (AF). 17 (10.3 %) patients with ICMP had sustained ventricular tachycardia (VT), which did not reach the detection frequency for ICD therapy; these VTs were only detected by devices and terminated spontaneously. Intragroup differences in the number of patients who received an appropriate treatment were statistically significant: 33 (32.6 %) in the ICMP group vs. 2 (3.1 %) in the NCMP group (р<0.006). Differences in the number of patients who received an inappropriate treatment were not statistically significant although their number was greater in the NCMP group than in the ICMP group (9 (14.1 %) vs. 11 (10.9 %), р>0.05).Conclusion      A higher requirement for the ICD treatment was revealed in patients with ICMP compared to patients with NCMP. The low demand for the ICD treatment in patients with NCMP and the more frequent inappropriate actuation of the devices in this patient group due to AF allow a conclusion that the criteria for primary prevention of SCD with ICD (LV EF ≤35% and clinically significant CHF) are not equally effective indications for ICD implantation in patients with ICMP and NCMP. It can be assumed that life-threatening ventricular arrhythmias are evident in patients with NCMP before the development of hemodynamically significant LV dysfunction and CHF, which warrants further research in this direction.

Implantable Cardioverter-Defibrillators are the Main Link in the Modern Concept of Sudden Cardiac Death Prevention. Problems and Prospects of the Development of the Method.

The article covers the development of the problem of sudden cardiac death prevention with the implantable cardioverter-defibrillators from the moment of creation of these devices to our days. The current concept of primary prevention of sudden cardiac death, based on the severity of manifestation of heart failure and left ventricular dysfunction, is not effective enough. Its practical application is difficult because it requires mass application of implantable defibrillators, with low predictive accuracy of these criteria in terms of development of life-threatening arrhythmias. The development of methods for visualizing the myocardium, allowing to assess the severity of myocardial fibrosis, as well as the possibilities of medical genetics, at the present stage, allows us to clarify indications for implantation of cardioverter-defibrillators and thereby significantly improve the concept of preventing sudden cardiac death with these instruments.

[Implantable cardioverter defibrillators in the prevention of sudden cardiac death]. / Implantiruemye kardiovertery-defibrilliatory v profilaktike vnezapnoi serdechnoi smerti.

The article highlights the role of implantable cardioverter defibrillators (ICDs) in the primary and secondary prevention of sudden cardiac death. It considers the results of multicenter studies comparing the efficacy of antiarrhythmic drugs and implantable devices in the primary and secondary prevention of sudden cardiac death, including that in patients with nonischemic cardiomyopathy and discusses quality of life in patients with ICDs.