[Heart rate variability in chronic cardiac failure insufficiency. Effect of severity and etiology]

The variability of the heart rate is a sign of the activation of the autonomic nervous system. This parameter was studied in 21 control subjects and 72 patients with chronic cardiac failure (20 stage II, 37 stage 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 analysis of the variability of the heart rate recorded during 24 hour Holter monitoring was performed with the Marquette Electronics 8000 software. Plasma noradrenaline was measured in whole blood by HPLC. The left ventricular ejection fraction was measured by echocardiography. There was a superior 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 sinus rhythm variability was proportional to the functional class (SDANN stage II: 96 +/- 34 ms; stage III: 63 +/- 34 ms; stage IV: 54 +/- 33 ms). Moreover, the non-spectral parameters were correlated to the ejection fraction and plasma noradrenaline levels (p < 0.01). In addition, with the same NYHA stage, plasma noradrenaline concentration, ejection fraction and heart rate, the SDNN and the pNN50 were over 50% lower in idiopathic cardiomyopathy than in ischaemic cardiomyopathy. In conclusion, the variability of the heart rate is reduced in chronic cardiac failure in relation with the severity and aetiology of the underlying disease.