Rabelo Daniel R, Rocha Manoel Otávio da Costa, de Barros Márcio V L, Silva José Luiz Padilha da, Tan Timothy C, Nunes Maria C P
Post-Graduate Program in Infectious Diseases and Tropical Medicine, School of Medicine, Federal University of Minas Gerais, Belo Horizonte, Brazil.
Echocardiography. 2014;31(1):67-73. doi: 10.1111/echo.12364. Epub 2013 Sep 15.
Previous studies suggest that microvascular abnormalities may contribute to the pathogenesis of Chagas' heart disease. Coronary flow reserve (CFR) expressed by the maximum achievable flow relative to baseline flow in the coronary microcirculation, may be useful in identifying patients who may be developing cardiac manifestations of the disease. This study aims to assess the CFR in patients with indeterminate form of Chagas' disease, and also to identify the determinants of CFR.
Sixty-four asymptomatic patients (37% male; age 49.9 ± 11.5 years) with normal cardiovascular exams classified as in indeterminate form of Chagas' disease underwent transthoracic dipyridamole (0.84 mg/kg in 6 min) stress echocardiography, and were compared with a control group of healthy patients. Coronary flow reserve was assessed on left anterior descending artery using pulsed Doppler as the ratio of maximal peak vasodilation (dipyridamole) to rest diastolic flow velocity. A treadmill exercise test was performed to rule out ischemia.
All patients had good functional capacity assessed by exercise testing with peak oxygen consumption (VO2 ) of 28 ± 11 mL/kg per minute, similar to the controls. There were no differences in the echocardiographic parameters of diastolic and systolic left ventricular function and right ventricular function between the patients and controls. Coronary flow reserve was significantly lower in Chagas' disease patients than those in healthy individuals (1.9 ± 0.4 vs. 2.6 ± 0.5; P < 0.001). Several factors were correlated with the CFR, including age, ejection fraction, left ventricular diastolic function, heart rate recovery, and the presence of Chagas' disease. In a multivariate analysis, age and positive serology for Chagas' disease were independent factors associated with the CFR.
Coronary flow reserve was impaired in Chagas' disease patients in the indeterminate form compared with healthy individuals with similar clinical features. Among all variables tested, age and positive serology for Chagas' disease were independent factors associated with the CFR.
先前的研究表明，微血管异常可能与恰加斯心脏病的发病机制有关。冠状动脉血流储备（CFR）通过冠状动脉微循环中相对于基线血流的最大可实现血流来表示，可能有助于识别可能正在出现该疾病心脏表现的患者。本研究旨在评估处于恰加斯病不确定形式的患者的CFR，并确定CFR的决定因素。
64例无症状患者（男性占37%；年龄49.9±11.5岁），心血管检查正常，被分类为恰加斯病不确定形式，接受经胸双嘧达莫（6分钟内0.84mg/kg）负荷超声心动图检查，并与健康患者对照组进行比较。使用脉冲多普勒评估左前降支动脉的冠状动脉血流储备，作为最大峰值血管扩张（双嘧达莫）与静息舒张期血流速度的比值。进行平板运动试验以排除缺血。
通过运动试验评估，所有患者的功能能力良好，峰值耗氧量（VO2）为每分钟28±11mL/kg，与对照组相似。患者和对照组之间左心室舒张和收缩功能以及右心室功能的超声心动图参数没有差异。恰加斯病患者的冠状动脉血流储备显著低于健康个体（1.9±0.4对2.6±0.5；P<0.001）。几个因素与CFR相关，包括年龄、射血分数、左心室舒张功能、心率恢复以及恰加斯病的存在。在多变量分析中，年龄和恰加斯病血清学阳性是与CFR相关的独立因素。
与具有相似临床特征的健康个体相比，处于不确定形式的恰加斯病患者的冠状动脉血流储备受损。在所有测试变量中，年龄和恰加斯病血清学阳性是与CFR相关的独立因素。
