Abstract 17297: Heart Rate-Guided Titration of Beta Blockers Stabilizes Ventricular Repolarization in Patients With Chronic Heart Failure
Background: We sought to evaluate the effects of heart-rate guided titration of beta-blockers on ventricular repolarization in patients with chronic heart failure (CHF).
Methods: In a prospective study we recorded 5-minute resting high-resolution ECGs in 100 patients with CHF and left ventricular ejection fraction (LVEF) <40%. In all subjects we measured heart rate and ventricular repolarization dynamics by QT variability index (QTVI). Target heart rate was defined as <70 bpm. In a subgroup of patients not reaching target heart rate, we uptitrated beta blocker dose and repeated high-resolution ECG measurements 3 months thereafter.
Results: At baseline, target heart rate (<70 bpm) was present in 46 patients (Group A), and in 54 patients heart rate was above target level (Group B). The two groups did not differ in age (53±12 years in Group A vs. 56±10 years in Group B, P=0.32), gender (male: 74% vs. 89%, P=0.10), LVEF (28.7±9.2% vs. 26.5±9.2, P=0.16), NT pro-BNP (3003±4623 pg/mL vs. 3247±2731 pg/mL, P=0.45), or creatinine (92±24 μmol/L vs. 94±24 μmol/L, P=0.45). In Group A, heart rate was significantly lower (63±5 bpm vs. 84±11 bpm in Group B, P<0.0001), and the same was true for QTVI (-1.54±0.425 in Group A vs. -1.30±0.52 in Group B, P=0.015). On multivariate analysis, the presence of target heart rate was an independent predictor of low QTVI, (P=0.017), but beta blocker dose was not. When uptitrating beta blocker therapy, QTVI decreased in 10 of 24 patients (42%). In these patients we found a significantly more prononunced decrease in heart rate than in the remaining cohort (-25±20 bpm vs. -15±17 bpm, P=0.017).
Conclusions: In patients with chronic heart failure treated with beta blockers, changes in ventricular repolarization appear to occur in parallel with changes of heart rate. Therefore, heart-rate guided individual titration of beta blocking therapy may be associated with stabilization of ventricular repolarization and could offer a protective strategy against ventricular arrhythmias in this patient cohort.
- © 2013 by American Heart Association, Inc.