QT interval prolongation and decreased heart rate variability in cirrhotic patients: relevance of hepatic venous pressure gradient and serum calcium
Résumé
A prolongation of QT interval has been shown in patients with cirrhosis and it is considered as part of the definition of the so-called “cirrhotic cardiomyopathy”. The aim of the present study was to assess the determinants of QT interval prolongation in cirrhotic patients. Forty-eight male patients with different stages of liver disease were divided in three subgroups according to Child-Pugh classification. All patients underwent a 24-hours electrocardiogram (ECG) Holter recording. The 24-hours mean of QT intervals corrected for heart rate (QTc) and the slope of the regression line QT/RR were calculated. Heart rate variability (HRV), plasma calcium and potassium concentration and hepatic venous pressure gradient (HVPG) were measured. QTc was progressively prolonged from Child A to Child C (p=0.001). A significant correlation between QTc and HVPG was found (p=0.003). Patients with alcohol-related cirrhosis presented QTc prolongation more frequently than patients with post-viral cirrhosis (p<0.001). A QT/RR slope was steeper in subjects with alcoholic aetiology as compared to viral aetiology (p=0.02), suggesting that these patients have a further QTc prolongation when heart rate decreases. Plasma calcium concentration was inversely correlated with QTc (p<0.001). The presence of severe portal hypertension was associated with decreased HRV (p<0.001). Cirrhotic patients with a more severe disease, especially of alcoholic aetiology, who show greater venous pressure gradient and lower calcium plasma levels, have an altered ventricular repolarization and a reduced vagal activity to the heart that may predispose to life-threatening arrhythmias.
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