Yu Cheuk-Man, Chan Joseph Yat-Sun, Zhang Qing, Omar Razali, Yip Gabriel Wai-Kwok, Hussin Azlan, Fang Fang, Lam Kai Huat, Chan Hamish Chi-Kin, Fung Jeffrey Wing-Hong
Division of Cardiology, Department of Medicine and Therapeutics, Prince of Wales Hospital, Chinese University of Hong Kong, Hong Kong.
N Engl J Med. 2009 Nov 26;361(22):2123-34. doi: 10.1056/NEJMoa0907555. Epub 2009 Nov 15.
Observational studies suggest that conventional right ventricular apical pacing may have a deleterious effect on left ventricular function. In this study, we examined whether biventricular pacing is superior to right ventricular apical pacing in preventing deterioration of left ventricular systolic function and cardiac remodeling in patients with bradycardia and a normal ejection fraction.
In this prospective, double-blind, multicenter study, we randomly assigned 177 patients in whom a biventricular pacemaker had been successfully implanted to receive biventricular pacing (89 patients) or right ventricular apical pacing (88 patients). The primary end points were the left ventricular ejection fraction and left ventricular end-systolic volume at 12 months.
At 12 months, the mean left ventricular ejection fraction was significantly lower in the right-ventricular-pacing group than in the biventricular-pacing group (54.8+/-9.1% vs. 62.2+/-7.0%, P<0.001), with an absolute difference of 7.4 percentage points, whereas the left ventricular end-systolic volume was significantly higher in the right-ventricular-pacing group than in the biventricular-pacing group (35.7+/-16.3 ml vs. 27.6+/-10.4 ml, P<0.001), with a relative difference between the groups in the change from baseline of 25% (P<0.001). The deleterious effect of right ventricular apical pacing occurred in prespecified subgroups, including patients with and patients without preexisting left ventricular diastolic dysfunction. Eight patients in the right-ventricular-pacing group (9%) and one in the biventricular-pacing group (1%) had ejection fractions of less than 45% (P=0.02). There was one death in the right-ventricular-pacing group, and six patients in the right-ventricular-pacing group and five in the biventricular-pacing group were hospitalized for heart failure (P=0.74).
In patients with normal systolic function, conventional right ventricular apical pacing resulted in adverse left ventricular remodeling and in a reduction in the left ventricular ejection fraction; these effects were prevented by biventricular pacing. (Centre for Clinical Trials number, CUHK_CCT00037.)
观察性研究表明，传统的右心室心尖部起搏可能对左心室功能产生有害影响。在本研究中，我们探讨了在射血分数正常的心动过缓患者中，双心室起搏在预防左心室收缩功能恶化和心脏重塑方面是否优于右心室心尖部起搏。
在这项前瞻性、双盲、多中心研究中，我们将177例已成功植入双心室起搏器的患者随机分为两组，分别接受双心室起搏（89例）或右心室心尖部起搏（88例）。主要终点为12个月时的左心室射血分数和左心室收缩末期容积。
12个月时，右心室起搏组的平均左心室射血分数显著低于双心室起搏组（54.8±9.1%对62.2±7.0%，P<0.001），绝对差值为7.4个百分点；而右心室起搏组的左心室收缩末期容积显著高于双心室起搏组（35.7±16.3 ml对27.6±10.4 ml，P<0.001），两组从基线的变化相对差值为25%（P<0.001）。右心室心尖部起搏的有害作用在预先设定的亚组中均有发生，包括有和无既往左心室舒张功能障碍的患者。右心室起搏组有8例患者（9%）射血分数低于45%，双心室起搏组有1例患者（1%）射血分数低于45%（P=0.02）。右心室起搏组有1例死亡，右心室起搏组有6例患者和双心室起搏组有5例患者因心力衰竭住院（P=0.74）。
在收缩功能正常的患者中，传统的右心室心尖部起搏导致不良的左心室重塑和左心室射血分数降低；双心室起搏可预防这些影响。（临床试验注册号，CUHK_CCT00037。）
