QT Adaptation during Exercise in Cirrhosis

Abstract

AIM: QT-interval prolongation is frequently seen in cirrhosis; whether it is simply a marker of disease severity is debated. Analysis of QT-interval behavior during physical exercise may disclose more specific abnormalities of cardiac repolarization of cirrhotic cardiomyopathy. MATERIALS AND METHODS: Thirty-eight out-patients with non-alcoholic liver cirrhosis and portal hypertension (32 males, aged 62 ± 9 years) and 36 sex- and age-matched healthy volunteers (32 males; aged 59 ± 7 years) underwent bicycle exercise test with QT-interval measurement, echocardiographic and Doppler analysis of systolic and diastolic left ventricular function, determinations of systemic hemodynamic and pro-brain natriuretic peptide concentration. RESULTS: Patients had longer Fridericia-corrected QT-interval than healthy subjects at baseline and peak-exercise, and reduced chronotropic index, despite similar predicted workload. Corrected-QT shortening extent at peak-exercise was the same; however, in early-exercise, corrected-QT increased in 6 healthy subjects versus 25 patients, and in patients the increase was greater and significantly delayed. QT hysteresis was greater in patients. Abnormal repolarization during exercise and recovery in patients with normal baseline corrected-QT did not correlate to Child-Pugh class and hemodynamic alterations, whereas patients with > 440 ms corrected-QT (n = 16) showed diastolic dysfunction and increased pro-brain natriuretic peptide. CONCLUSIONS: QT behavior during physical exercise supports the hypothesis of anomalous modulation of potassium currents in cirrhosis; only long rest corrected-QT correlates to clinical signs of cirrhotic cardiomyopathy.