Thackray Simon D R, Ghosh Justin M, Wright Graham A, Witte Klaus K A, Nikitin Nikolay P, Kaye Gerald C, Clark Andrew L, Tweddel Ann, Cleland John G F
Department of Academic Cardiology, University of Hull, Castle Hill Hospital, Kingston-upon-Hull, United Kingdom.
Am Heart J. 2006 Oct;152(4):713.e9-13. doi: 10.1016/j.ahj.2006.07.007.
Beta-blockers are effective for the treatment of heart failure, but their mechanism of action is unresolved. Heart rate reduction may be a central mechanism or a troublesome side effect.
A randomized, double-blind, parallel group study comparing chronic higher-rate (80 pulses per minute) with lower-rate (60 pulses per minute) pacing in pacemaker-dependent patients with symptomatic left ventricular (LV) systolic dysfunction, receiving beta-blockers. Gated radionuclide ventriculography (RNVG) was performed at baseline and after at least 9 months. The primary outcome was change in LV volumes, as a marker of beneficial reverse remodeling, from baseline to follow-up.
Forty-nine patients were randomized. Mean age was 74 +/- 6 years and with LV ejection fraction of 26% +/- 9% at baseline. During 14 +/- 13 months of follow-up, 21 patients (43%) died and 25 (51%) completed the study protocol: 12 in the higher-rate and 13 in the lower-rate group. Mean LV end-diastolic (higher rate +20 +/- 104 mL vs lower rate -65 +/- 92 mL, P = .03) and systolic (higher rate +29 +/- 83 mL vs lower rate -60 +/- 74 mL, P = .006) volumes increased with higher-rate versus lower-rate pacing, whereas LV ejection fraction declined (higher rate -4.2% +/- 4.4% vs lower rate +2.2% +/- 5.4%, P = .002).
Reversal of beta-blocker-induced bradycardia has deleterious effects on ventricular function, suggesting heart rate reduction is an important mediator of their effects. The prognosis of patients with pacemakers and heart failure is poor.
β受体阻滞剂对心力衰竭治疗有效，但其作用机制尚未明确。心率降低可能是核心机制，也可能是不良副作用。
一项随机、双盲、平行组研究，比较起搏器依赖且有症状性左心室（LV）收缩功能障碍并接受β受体阻滞剂治疗的患者，慢性较高心率（每分钟80次搏动）起搏与较低心率（每分钟60次搏动）起搏的效果。在基线及至少9个月后进行门控放射性核素心室造影（RNVG）。主要结局指标是从基线到随访期间左心室容积的变化，作为有益的逆向重构的标志物。
49例患者被随机分组。平均年龄为74±6岁，基线时左心室射血分数为26%±9%。在14±13个月的随访期间，21例患者（43%）死亡，25例（51%）完成研究方案：较高心率组12例，较低心率组13例。较高心率起搏组的左心室舒张末期容积（较高心率组+20±104 mL vs较低心率组-65±92 mL，P = 0.03）和收缩末期容积（较高心率组+29±83 mL vs较低心率组-60±74 mL，P = 0.006）较较低心率起搏组增加，而左心室射血分数下降（较高心率组-4.2%±4.4% vs较低心率组+2.2%±5.4%，P = 0.002）。
逆转β受体阻滞剂引起的心动过缓对心室功能有有害影响，提示心率降低是其作用的重要介导因素。起搏器植入且合并心力衰竭患者的预后较差。
