RISK STRATIFICATION OF SUDDEN CARDIAC DEATH OF PATIENTS WITH DILATED CARDIOMYOPATHY

To reveal independent predictors of ventricular tachyarrhythmia (VTA) and predict the risk of sudden cardiac death (SCD), 209 patients with dilated cardiomyopathy and chronic heart failure (CHF) of Functional Class II III (NYHA) aged 47.2±11.7 years (17 59 years), including 61 women (29.2%) and 148 men (70.8%) were examined. The sinus rhythm was documented in 129 patients (61.7%), atrial fibrillation, in 80 patients (38.3%). The QRS width was 123±29 ms. The complete left bundle branch block (LBBB) with the QRS complex width of 167±32 ms was found in 59 patients (28.2%). The follow-up period lasted for 32.8±7.4 months. All patients received the standard background therapy of CHF. The study assessment included physical examination, echocardiography, ECG Holter monitoring, and 6 minute walk test. ECG was recorded within 7 minutes, including 2 minutes of ECG recording at physical exertion (power: 25 W; heart rate: 102±7.6 bpm) and 5 minutes of recording at rest, with analysis of ventricular ectopies, heart rate turbulence (HRT), QT interval dispersion, and microvolt T wave alternans (mTWA). During the follow-up period (32.8±7.4 months), VTA were revealed in 45 patients (21.5%) with dilated cardiomyopathy, associated with syncope in 7 patients, successful cardio pulmonary resuscitation in 4 patients (1.91%); sudden cardiac death occurred in 11 subjects (5.26%). ECG Holter monitoring and telemetry of implanted devices revealed 30 patients (14.4%) with VTA. Cardioverters-defibrillators (ICD) were implanted as clinically indicated to 17 patients (8.13%), cardiac resynchronization therapy (CRT) was performed in 31 patients (14.8%), and resynchronizing devices with the cardioverter-defibrillator option (CRT D) were implanted to 28 subjects (13.4%). mTWA was assessed in 126 patients (60.3%), the pathological mTWA was revealed in 39 cases, including 35 patients with SCD and/or VTA and in 4 patients without VTA. Negative mTWA tests were observed in 69 subjects without VTA and 5 patients with episodes of non-sustained ventricular tachycardia (VT). The HRT parameters were assessed in 69 patients. The pathological HRT was found in 43 subjects with SCD and/or VTA and 3 patients without VTA. The physiological HRT was revealed in 15 patients without VTA and 8 subjects with paroxysms of non-sustained VT. The QT interval dispersion was assessed in all 209 study subjects; positive tests were documented in 110 patients, and negative, in 99 ones. Episodes of VTA were revealed in 46 patients with the positive tests and were not found in 64 ones. The negative QT interval dispersion test was documented in 11 patients with VTA paroxysms and 88 patients without VTA. The highest predictive value was revealed for mTWA (sensitivity: 85%, specificity: 70%, area under the curve: S=0.826; CI 95%: 0.749 0.902. p=0.000, with the mTWA cut point ≥33.5 μV) and the left ventricular dysfunction (threshold value of LV EF≤20.5%; sensitivity: 90%, specificity: 80%, area under the curve: S=0.903; CI 95%: 0.849-0.958, p=0.000). Thus, the data obtained were in line with the results of multicenter studies of markers of myocardial electric instability, which affect the clinical prognosis of patients with depressed left ventricular contractile function. The use of the authors’ prognostic model for screening stratification of patients with dilated cardiomyopathy permitted them to select a group of candidates for prophylactic implantation of cardioverter-defibrillator.

dilated cardiomyopathy, chronic heart failure, ventricular tachyarrhythmia, sudden cardiac death, electrocardiography, echocardiography, heart rate turbulence, microvolt T wave alternans

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