ABSTRACT
AIM: to study microvolt T-wave alternans (mTWA) and heart rate turbulence (HRT) in patients with hypertrophic cardiomyopathy (HCMP). MATERIAL AND METHODS: We examined 50 patients with HCMP: 15 (28%) with obstructive form, 23 (46%) with major risk factors of sudden cardiac death (SCD), 7 (14%) with left ventricular thickness more or equal 3 cm, 6 (12%) with family history of SCD, 16 (32%) with attacks of nonsustained ventricular tachycardia (NVT), 5 (10%) with episodes of syncope. Control group comparable by age and gender composition comprised 50 persons without cardiovascular diseases. All patients were subjected to 24-hour ECG monitoring with registration of parameters of variability and HRT (turbulence onset [TO], turbulence slope), maximal mTWA values, mTWA at heart rate 100 bpm, mTWA at 05.00 AM (mTWA05:00). RESULTS: Patients with HCMP compared to controls were characterized by significantly higher values of mTWA05:00 (19 [13;30] and 9 [4;15] mcV, respectively, p<0.001). There was tendency to greater prevalence of pathological HRT values in patients with HCMP compared with healthy subjects (p=0.083). Prevalence of pathological TO values among patients (16%) was significantly higher than among controls (2%), (p<0.05). CONCLUSIONS: Compared to healthy subjects patients with HCMP were characterized by higher mTWA05:00 and higher prevalence of pathological values of TO. mTWA was directly related to numbers of ventricular extrasystoles and NVT attacks. Patients with attacks of NVT compared with those without had lower SDNN pNN50.
