Factors that Determined a Positive Response to Resynchronization Therapy in Patients With Chronic Heart Failure and Cardiac Dyssynchrony. One Center Experience.

AIM: To evaluate the efficacy of cardiac resynchronization therapy (CRT) in patients with chronic heart failure (CHF) associated with cardiac dyssynchrony and to identify the factors that influence the CRT efficacy. MATERIAL AND METHODS: This retrospective study included 155 patients after implantation of CRT devices. The CRT devices with a built-in cardioverter-defibrillator (CRT-D) and without it (CRT-P) were implanted in 139 (89.7%) and 16 (10.3%) patients, respectively. The follow-up period was 52.37±35.94 months. Based on the study results, two groups of patients were formed depending on the presence of a clinical response to CRT, responders and non-responders. The factors that influenced the clinical response to CRT were studied. The effect of the baseline state of patients on the effect of therapy was assessed. The need for CRT optimization and a possibility of using electrocardiographic criteria for that purpose were studied. Modern devices and leads for CRT, their functional capabilities and their influence on the CRT efficacy were characterized. Statistical analysis was performed with an IBM SPSS Statistics 21.0 (Chicago, USA) package. RESULTS: CRT implantation with the left ventricular lead placement according to the traditional technique, through the coronary sinus, was successful in 130 (87.9%) patients. Difficulties with the left ventricular lead placement were noted in 13 (8.3%) patients when other techniques were used. After 6 months, a hemodynamic and clinical response was observed in 112 (72.2%) patients, and no positive response in 43 (27.8%). The increase in left ventricular ejection fraction in the responder group was more than 21.8±3.7%, which was associated with an improvement of the 6-minute walk test results. Th clinical response was significantly influenced by the possibility of stimulation from the basal parts of the heart; the use of more modern devices for CRT and quadripolar left ventricular leads; timely CRT optimization; and persistent dyssynchrony in non-responders. During the follow-up period, 34 (21.9%) patients died. The death rate in the non-responder group was significantly higher than in the responder group, 18 (41.3%) vs. 16 (14.3%), p=0.001. The main cause of death in the group of non-responders was CHF. Heart transplantation was performed in 3 (1.9%) patients. CONCLUSION: CRT increases the life span and improves the quality of life in patients with CHF and cardiac dyssynchrony. There was a group of patients with no benefit from CRT in this study. Modern devices allow increasing the number of patients who benefit from CRT. Periodic optimization of CRT is necessary. When optimizing CRT, it is possible to use electrocardiographic criteria of effectiveness: duration of the QRS complex and changes in the position of the electrical axis of the heart.

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.