Effects of losartan treatment on cardiac autonomic control during volume loading in patients with DCM

This study evaluated the effect of angiotensin II receptor blockade on card iac autonomic control adaptation and urine output in response to acute isot onic volume load in patients with idiopathic dilated cardiomyopathy (DCM) a nd asymptomatic to mildly symptomatic heart failure. Left ventricular volum es and heart rate variability measurements were assessed at baseline and du ring intravenous saline load in 14 patients before and after 2 mo of losart an treatment. After losartan treatment, blood pressure values were lower, w hereas left ventricular ejection fraction was higher (F = 79, P< 0.001), th an before treatment. During saline load, ejection fraction decreased before losartan treatment (F = 5.6, P< 0.05) but did not change after treatment. Urinary volume, unchanged during saline load in untreated patients, increas ed after losartan (F = 9.38, P< 0.001). Time-domain measurements that repre sent vagal modulation of heart rate (root-mean-square successive difference s and percentage of differences between successive R-R intervals >50 ms) de creased during saline load in untreated patients (F = 3.1, P< 0.05 and F = 6.5, P< 0.01, respectively), but not after losartan. Similarly, a decrease in very low frequency (F = 3.2, P< 0.05), low-frequency (F = 2.9, P< 0.05), and high-frequency power (F = 6.1, P< 0.01) after saline load was observed only in untreated patients. In patients with DCM, losartan treatment impro ves the cardiac autonomic adaptation and increases urine output in response to volume overload.