INDICATIONS FOR IMPLANTATION AND EFFICIENCY OF CARDIOVERTER-DEFIBRILLATORS IN PATIENTS WITH DILATED CARDIOMYOPATHY

Purpose. To assess the frequency and predictors of appropriate shocks of cardioverter-defibrillators in patients with dilated cardiomyopathy (DCM) syndrome and the impact on the total mortality and sudden cardiac death (SCD).
Material and Methods. A total of 275 patients with DCM syndrome (average age of 46.8 ± 12.5 years; 185 males and 90 females) were observed. Inclusion criteria were left ventricular (LV) end-diastolic diameter (EDD) more than 5.5 cm and LV ejection fraction (EF) less than 50%. Patients with coronary artery stenosis more than 50% were excluded. Implantable cardioverter-defibrillator (ICD) (n=44) and cardiac resynchronization therapy defibrillator (CRT-D) (n=32) were implanted in 76 (27.6%) patients (53 males and 23 females, average age of 48.9±12.9 years, LV EDD of 6.7±0.8 cm, and LV EF of 28.2±9.9%). A comparison group comprised 199 patients (72.4%) without devices (132 males and 67 females, average age of 46.0±12.3 years, LV EDD of 6.5±0.8 cm, and LV EF of 32.0±10.2%). The average follow-up was 27 (24; 30) months.
Results. SCD in patients with DCM syndrome was recorded in 2.9% of cases; the total mortality rate was 18.9%; the rate of death + transplantation was 22.6%. The SCD, total mortality, and death+transplantation rates were 2.6% (4.6/0%), 23.7% (22.7/25.0%), and 32.9% (34.1/31.3%) in patients with devices (ICD/CRT-D) and 3.0%, 17.1%, and 16.6% in patients without devices, respectively. The rate of SCD+appropriate shocks (ASR) was significantly higher in study group: 26.3 vs 3.0% in comparison group (p<0.001). The nature of DCM syndrome was predominantly inflammatory (53%), primary (genetic) (19.6%), and multifactorial (25.1%). Genetic forms of DCM were represented by non-compaction cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy (ARVC), myopathies, and amyloidosis. The pathogenic mutations in the genes LMNA (n=1), DES (n=2), DSP (n=2), EMD (n=2), PKP2 (n=1), TTR (n=1), MUH7+MyBPC3 (n=1), and MyBPC3 (n=4) were detected. The ASR (ICD/CRT-D) rate was 23.7% (n=13/5). The only reliable predictor of ASR was the generic nature of DCM syndrome, identified in 100% of patients with shocks (in the presence of myocarditis in 77.8%/isolated in 22.2%) in comparison with 51.7% (29.3/22.4%) in patients without ASR (p<0.002, AUC 0.747, RR 1.66, 95% CI 0.711-3.885). Ventricular tachycardia (VT) was registered in 84% of patients with shocks (stable/unstable VT rates of 17/67%) vs 1.7/72%, in patients without shocks (р=0.06). In patients with shocks, low QRS voltage (39 vs 6.9%, р<0.05) and the absence of LV hypertrophy signs on the ECG (77.6 vs 58.6%, р>0.05) were registered more often. The average LV EF was higher in patients with ASR (34.4±9.7%) in comparison with patients without ASR (25.9±8.8%), р<0.005. 

Conclusions. The genetic nature of DCM syndrome is an important predictor of appropriate shocks and an independent selection criterion for ICD/CRT-D implantation. Age, NYHA class, and LV EF did not show prognostic significance. Additional predictors of appropriate shocks were sustained/unsustained VT, low QRS voltage, and the absence of LV hypertrophy signs on the ECG. 

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