Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.
Circulation. 2011 Oct 18;124(16):1719-26. doi: 10.1161/CIRCULATIONAHA.111.043042. Epub 2011 Sep 19.
Heart failure is associated with frequent hospitalizations, often resulting from volume overload. Measurement of intrathoracic impedance with an implanted device with an audible patient alert may detect increases in pulmonary fluid retention early. We hypothesized that early intervention could prevent hospitalizations and affect outcome.
We studied 335 patients with chronic heart failure who had undergone implantation of an implantable cardioverter-defibrillator alone (18%) or with cardiac resynchronization therapy (82%). All devices featured a monitoring tool to track changes in intrathoracic impedance (OptiVol) and other diagnostic parameters. Patients were randomized to have information available to physicians and patients as an audible alert in case of preset threshold crossings (access arm) or not (control arm). The primary end point was a composite of all-cause mortality and heart failure hospitalizations. During 14.9±5.4 months, this occurred in 48 patients (29%) in the access arm and in 33 patients (20%) in the control arm (P=0.063; hazard ratio, 1.52; 95% confidence interval, 0.97-2.37). This was due mainly to more heart failure hospitalizations (hazard ratio, 1.79; 95% confidence interval, 1.08-2.95; P=0.022), whereas the number of deaths was comparable (19 versus 15; P=0.54). The number of outpatient visits was higher in the access arm (250 versus 84; P<0.0001), with relatively more signs of heart failure among control patients during outpatient visits. Although the trial was terminated as a result of slow enrollment, a post hoc futility analysis indicated that a positive result would have been unlikely.
Use of an implantable diagnostic tool to measure intrathoracic impedance with an audible patient alert did not improve outcome and increased heart failure hospitalizations and outpatient visits in heart failure patients. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT 00480077.
心力衰竭常因血容量负荷过重而导致频繁住院。使用带有可听患者警报的植入式设备测量胸腔内阻抗，可能会早期检测到肺液潴留的增加。我们假设早期干预可以预防住院并影响预后。
我们研究了 335 名患有慢性心力衰竭的患者，他们单独植入了植入式心脏复律除颤器（18%）或心脏再同步治疗（82%）。所有设备都配备了一种监测工具，用于跟踪胸腔内阻抗（OptiVol）和其他诊断参数的变化。患者被随机分为两组：一组可将信息提供给医生和患者，如果预设阈值超过（接入组），则发出可听警报；另一组则不提供（对照组）。主要终点是全因死亡率和心力衰竭住院的复合终点。在 14.9±5.4 个月的随访中，接入组有 48 例（29%）患者发生了这一终点事件，对照组有 33 例（20%）患者发生了这一终点事件（P=0.063；风险比，1.52；95%置信区间，0.97-2.37）。这主要归因于心力衰竭住院的增加（风险比，1.79；95%置信区间，1.08-2.95；P=0.022），而死亡率相当（19 例与 15 例；P=0.54）。接入组的门诊就诊次数更高（250 次与 84 次；P<0.0001），而对照组在门诊就诊期间，心力衰竭的迹象相对更多。尽管由于入组缓慢而提前终止了试验，但事后无效性分析表明，阳性结果不太可能出现。
使用带有可听患者警报的植入式诊断工具测量胸腔内阻抗并不能改善预后，反而会增加心力衰竭患者的心力衰竭住院率和门诊就诊次数。临床试验注册网址：http://www.clinicaltrials.gov。唯一标识符：NCT 00480077。
