Experience with bisoprolol in long-QT1 and long-QT2 syndrome

The protective effect of beta-blockers in patients with inherited Long-QT syndrome is well established. Recent reports have suggested that beta-blockers are not equally effective in Long-QT (LQT). Bisoprolol is an attractive candidate for use in LQT because of its cardioselective properties and favorable side-effect profile.

We performed a retrospective cohort study of 114 consecutive patients with gene-positive Long-QT syndrome type 1 (LQT1) or Long-QT syndrome type 2 (LQT2) treated with bisoprolol, nadolol or atenolol with a total of 580 person-years of follow-up. Electrocardiogram (ECG) parameters and cardiac events during follow-up were compared. In addition, exercise treadmill testing was performed in bisoprolol-treated patients.

Fifty-nine patients were treated with bisoprolol, 39 with atenolol and 16 with nadolol. Overall, 59 % were females and 62 % had LQT1. Baseline heart rate and corrected QT (QTc) interval were similar between the groups. QTc shortening was observed in individuals on bisoprolol (ΔQTc -5 ± 31 ms; p = 0.049) and nadolol (ΔQTc -13 ± 16 ms; p = 0.02) but not on atenolol (ΔQTc +9 ± 24 ms; p = 0.16). Median follow-up was similar for bisoprolol and nadolol (3 years), but longer for atenolol (6 years; p = 0.03); one cardiac event occurred in the bisoprolol group (1.7 %) and two events occurred in the atenolol group (5.1 %; p = 0.45), whereas none occurred in nadolol-treated patients. Beta-blocker efficacy was not affected by the underlying genotype. The antiadrenergic effect of bisoprolol correlated with the reduction of peak heart rates at exercise testing.

Bisoprolol treatment results in QTc shortening in gene-positive LQT1 and LQT2 patients and is well tolerated during long-term administration. The equivalence of bisoprolol for protection from ventricular arrhythmia in LQT patients compared to established beta-blockers remains unknown. Further large-scale studies are required.