Division of Cardiology, Department of Medicine, Columbia University Medical Center, 622 West 168th Street, New York, NY 10032, USA.
Europace. 2011 Oct;13(10):1459-63. doi: 10.1093/europace/eur127. Epub 2011 May 7.
Chronotropic incompetence (CI) is a common finding in patients with advanced chronic heart failure (CHF) and is associated with a worse functional capacity. Whether rate responsive pacing with cardiac resynchronization therapy (CRT) would acutely improve exercise performance in patients with advanced CHF and severe CI (<70% age-predicted maximum heart rate) is unknown.
Patients (n = 13) with CHF, a CRT device, and severe CI were randomized in a double-blind crossover pilot study to either DDD (control) or DDDR (rate responsive) pacing. Six minutes walk test (6MWT) distance, oxygen consumption at anaerobic threshold (VO(2) @ AT), and maximal oxygen consumption (VO(2) max) were measured. One week later, testing was repeated in the alternate pacing mode. Rate responsive pacing commenced with standard settings in only 9 of 13 (69%) patients. In these 9 subjects, 6MWT distance improved acutely from 358.5 ± 40.7 to 376.8 ± 24.5 m with DDDR pacing (P< 0.05). VO(2) max did not improve with DDDR pacing (14.0 ± 3.2 mL/kg/min) compared with DDD pacing (13.9 ± 3.0 mL/kg/min; P= 0.69). VO(2) @ AT tended towards improvement with DDDR pacing (10.8 ± 2.9 mL/kg/min) compared with DDD pacing (9.6 ± 1.8 mL/kg/min; P= 0.29). There was a linear relationship between the increase in heart rate at minute 3 during rate responsive pacing and improvement in VO(2) @ AT (r = 0.83, P< 0.05).
When rate responsive pacing using a CRT device is achieved in patients with advanced CHF and severe CI, parameters of aerobic exercise performance improve acutely. Routine exercise testing to ensure successful restoration of heart rate response may be beneficial to optimize CRT settings in this patient population.
变时性功能不全（CI）是晚期慢性心力衰竭（CHF）患者的常见表现，与较差的功能能力相关。使用心脏再同步治疗（CRT）的频率适应性起搏是否会急性改善晚期 CHF 伴严重 CI（<70%年龄预测最大心率）患者的运动表现尚不清楚。
本双盲交叉先导研究纳入了 13 名 CHF 患者、携带 CRT 设备且 CI 严重的患者，随机分为双腔（DDD，对照组）或双腔（DDDR，频率适应性）起搏。测量 6 分钟步行测试（6MWT）距离、无氧阈时的耗氧量（VO2@AT）和最大耗氧量（VO2max）。一周后，在交替起搏模式下重复测试。仅 13 例（69%）患者中的 9 例可起始标准设置的频率适应性起搏。在这 9 例患者中，DDDR 起搏时 6MWT 距离从 358.5 ± 40.7 米显著改善至 376.8 ± 24.5 米（P<0.05）。与 DDD 起搏时相比，DDDR 起搏时 VO2max 并未改善（14.0 ± 3.2 毫升/公斤/分钟）（13.9 ± 3.0 毫升/公斤/分钟；P=0.69）。与 DDD 起搏时相比，DDDR 起搏时 VO2@AT 呈改善趋势（10.8 ± 2.9 毫升/公斤/分钟）（9.6 ± 1.8 毫升/公斤/分钟；P=0.29）。在频率适应性起搏的第 3 分钟时心率的增加与 VO2@AT 的改善呈线性关系（r=0.83，P<0.05）。
在晚期 CHF 伴严重 CI 患者中使用 CRT 设备实现频率适应性起搏时，有氧运动表现的参数会急性改善。常规运动测试以确保成功恢复心率反应可能有益于优化该患者人群的 CRT 设置。
