RESUMO
BACKGROUND/AIMS: QT interval prolongation is frequent in cirrhosis, predicts a poor prognosis and may trigger severe ventricular arrhythmias. Our aim was to evaluate the effect of chronic beta-blockade on QT prolongation. METHODS: Clinical and laboratory evaluation, ECG and hepatic vein pressure gradient (HVPG) measurement were performed in 30 cirrhotic patients before and 1-3 months after prophylactic nadolol. QT was corrected for heart rate by the cirrhosis-specific formula and other formulas. RESULTS: QT(cirrhosis) was prolonged in 10 patients (33%); HVPG was increased in all cases. QT(cirrhosis) was correlated with the Child-Pugh score (r=0.40; p=0.027). Nadolol shortened QT interval only with the Bazett formula (p=0.01), remaining unchanged with the other formulas. The QT interval shortened only if prolonged at baseline (from 473.3+/-5.5 to 458.4+/-6.5 ms; p=0.007), while it lengthened when normal (from 429.8+/-3.1 to 439.3+/-2.9 ms; p=0.01). QTc changes were directly related to the baseline value (p<0.001). HVPG decreased from 19.4+/-0.8 to 15.6+/-1.3 mmHg (p=0.004). The HVPG changes did not correlate with QTc changes. CONCLUSIONS: Chronic beta-blockade shortens the QT interval only in patients with prolonged baseline values, and this is likely due to a direct cardiac effect.
