RESUMEN
Objective: the aim of this work is to study HRV parameters in patients with unstable angina
Materials and Methods: the study comprised 50 patients with unstable angina; 35 males and 15 females with mean age 45 +/- 94 yrs. beside ten healthy control subjects. All patients and control subjects were subjected to thorough history taking, full clinical examination, electrocardiography, routine laboratory investigations, assessment of heart rate variability [HRV] using time domain [NN 50 and RMSSD] for non-spectral analysis and frequency domain [LF, HF and LF / HF ratio] for spectral analysis, echocardiographic examination and coronary angiography
Results: there was significant global reduction in HRV parameters in patients with unstable angina compared to control group as mean NN 50 was 3.2 ms in patients compared to 20.1 ms in control group [P < 0.01]. Mean RMSSD was 10.1 ms in patients us 42.1 ms in control group [P < 0.01], HF was 50 ms2 in patients us 350 ms2 in control group and HF was 32.5 ms2 in patients compared to 246 ms2 in control group. However, there was no significant difference between the patients and controls as regards LF/HF ratio [P > 0.05]. Mean W H F ratio was significantly higher. Among patients who experienced recurrent chest pain during hospitalization as the mean LF/HF ratio among five patients who developed recurrent chest pain was 1.9 vs 1.5 in other patients [P < 0.05]. There was significant correlation between HRV and both EF [r = 0.8, P < 0.05] and severity of coronary artery disease [r = 0.7, P < 0.05]. There was no significant correlation between HRV and age [r = 0.2, P > 0.05, end systolic diameter [r = 0.3, P > 0.05] and end diastolic diameter [r = 0.02, P > 0.05] of the left ventricle
Conclusion: all parameters of HRV except LF/H.F ratio were significantly lower among patients with unstable angina compared to control group. HF/HF ratio in particular was significantly lower among patients who experienced recurrent chest pain during hospitalization. Finally there was positive correlation between HRV parameters .and both EF and severity of coronary heart disease
Comment: HRV can be a useful parameter for risk stratification of patients with unstable angina