Bangalore Sripal, Yao Siu-Sun, Chaudhry Farooq A
Department of Medicine, Division of Cardiology, St. Luke's-Roosevelt Hospital and Columbia University, New York, NY, USA.
Am J Cardiol. 2006 Mar 1;97(5):742-7. doi: 10.1016/j.amjcard.2005.09.111. Epub 2006 Jan 10.
The role of heart rate (HR) reserve (HRR) in the risk stratification of patients who undergo dobutamine stress echocardiography is not well defined. This study evaluated 1,323 patients (mean age 63 +/- 13 years, 47% men) who underwent dobutamine stress echocardiography. Abnormal stress echocardiographic results were defined as those with stress-induced ischemia. HRR was defined as [(peak HR - HR at rest)/(220 - age - HR at rest)] x 100, with HRR <70% defined as low. Follow-up data (2.7 +/- 1.1 years) for confirmed myocardial infarction (n = 16) and cardiac death (n = 58) were obtained. HRR risk stratified patients into normal and abnormal subgroups (event rate 1.1%/year vs 4.2%/year, p <0.0001) and further risk stratified patients into normal (adjusted HR 1 [reference] vs 2.88, p = 0.04) and abnormal (adjusted HR 4.17 vs 10.09, p <0.0001) stress echocardiography groups. Low HRR (relative risk [RR] 2.15, 95% confidence interval [CI] 1.23 to 4.01, p = 0.013) was an independent predictor of cardiac event even after controlling for standard cardiovascular risk factors, other stress electrocardiographic variables, and stress echocardiographic variables. Low HRR (chi-square 32) was superior to 85% maximum predicted HR (MPHR; chi-square 18) and provided incremental value over stress echocardiography and 85% MPHR (global chi-square increased from 48.3 to 54 to 61.3, p <0.0001) in a model consisting of stress echocardiography, MPHR, and HRR. In conclusion, HRR can further risk stratify patients who undergo dobutamine stress echocardiography and provides independent and incremental prognostic value over standard cardiovascular risk factors and also independent of echocardiographic myocardial ischemia and left ventricular dysfunction and is superior to 85% MPHR. In the setting of low HRR, normal stress echocardiographic results are prognostically less benign, whereas abnormal stress echocardiographic results are prognostically more malignant.
心率（HR）储备（HRR）在接受多巴酚丁胺负荷超声心动图检查患者的风险分层中的作用尚未明确界定。本研究评估了1323例接受多巴酚丁胺负荷超声心动图检查的患者（平均年龄63±13岁，47%为男性）。负荷超声心动图检查结果异常定义为存在负荷诱发的心肌缺血。HRR定义为[（峰值心率-静息心率）/（220-年龄-静息心率）]×100，HRR<70%定义为低HRR。获得了确诊心肌梗死（n=16）和心源性死亡（n=58）的随访数据（2.7±1.1年）。HRR将患者分为正常和异常亚组（事件发生率分别为1.1%/年和4.2%/年，p<0.0001），并进一步将患者分为负荷超声心动图检查结果正常（调整后HR为1[参考值]对2.88，p=0.04）和异常（调整后HR为4.17对10.09，p<0.0001）亚组。即使在控制了标准心血管危险因素、其他负荷心电图变量和负荷超声心动图变量后，低HRR（相对风险[RR]2.15，95%置信区间[CI]1.23至4.01，p=0.013）仍是心脏事件的独立预测因素。低HRR（卡方值32）优于85%最大预测心率（MPHR；卡方值18），并且在由负荷超声心动图、MPHR和HRR组成的模型中，相对于负荷超声心动图和85%MPHR提供了增量价值（总体卡方值从48.3增加到54再到61.3，p<0.0001）。总之，HRR可进一步对接受多巴酚丁胺负荷超声心动图检查的患者进行风险分层，并且相对于标准心血管危险因素提供独立的增量预后价值，还独立于心室壁运动异常和左心室功能障碍，且优于85%MPHR。在低HRR情况下，负荷超声心动图检查结果正常的患者预后并非良性，而负荷超声心动图检查结果异常的患者预后更差。
