HEART-RATE-VARIABILITY IN CHRONIC CARDIAC -FAILURE - INFLUENCE OF SEVERITY AND ETIOLOGY

The variability of the heart rate is a sign of the activation of the a utonomic nervous system. This parameter was studied in 21 control subj ects and 72 patients with chronic cardiac failure (20 stage II, 37 sta ge III and 15 stage IV of the NYHA) due to ischaemic heart disease in 48 cases and idiopathic in 24 cases. Spectral and non-spectral analysi s of the variability of the heart rate mic heart disease in 48 cases a nd idiopathic in 24 cases. Spectral and non-spectral analysis of the v ariability of the heart rate recorded during 24 hour Holter monitoring was performed with the Marquette Electronics 8000 software. Plasma no radrenaline was measured in whole blood by HPLC. The left ventricular ejection fraction was measured by echocardiography. There was a superi or to 40 % decrease in non-spectral and over 50 % decrease in spectral parameters in patients with cardiac failure. This was more pronounced when the cardiac failure was in an advanced stage. The decrease in si nus rhythm variability was proportional to the functional class (SDANN stage II : 96 +/- 34 ms; stage III: 63 +/- 34 ms; stage IV : 544 +/- 33 ms). Moreover, the non-spectral parameters were correlated to the e jection fraction and plasma nonradrenaline levels (p < 0.01). In addit ion, with the same NYHA stage, plasma noradrenaline concentration, eje ction fraction and heart rate, the SDNN and the pNN50 were over 50 % l ower in idiopathic cardiomyopathy than in ischaemic cardiomyopathy. In conclusion, the variability of the heart rate is reduced in chromic c ardiac failure in relation with the severity and aetiology of the unde rlying disease.