Dynamic changes in microcirculatory blood flow during dobutamine stress assessed by quantitative myocardial contrast echocardiography.

BACKGROUND: Although dobutamine-atropine stress echocardiography (DASE) has been widely used for evaluating patients with coronary artery disease (CAD), dynamic changes that occur at microcirculatory level during each stage of stress have not been demonstrated in humans. AIM: We sought to determine variations in myocardial blood flow (MBF) during DASE using quantitative real time myocardial contrast echocardiography (RTMCE). METHODS: We studied 45 patients who underwent coronary angiography and RTMCE. Replenishment velocity of microbubbles in the myocardium (ß) and MBF reserves were obtained at baseline, intermediate stage (70% of maximal predicted heart rate), peak stress, and recovery phase. RESULTS: ß and MBF reserves were lower in patients with than without CAD at intermediate (1.65 vs. 2.10; P=0.001 and 2.44 vs. 3.23; P=0.004) and peak (1.63 vs. 3.00; P<0.001 and 2.14 vs. 3.98; P<0.001, respectively). In patients without CAD, ß, and MBF reserves increased from intermediate to peak and decreased at recovery, while in those without CAD reserves did not change significantly. Optimal cutoff values of ß reserve at intermediate, peak, and recovery were 1.78, 2.09, and 1.70, with areas under the curves of 0.80 (95%CI=0.67-0.94), 0.89 (95%CI=0.79-0.99), and 0.69 (95%CI=0.53-0.85). Sensitivity, specificity and accuracy for detecting CAD at intermediate stage were 68% (95%CI=48-89), 85% (95%CI=71-98), and 78% (95%CI=66-90), at peak stress were 79% (95%CI=61-97), 96% (95%CI=89-100), and 89% (95%CI=80-98), and at recovery were 74% (95%CI=54-93), 65% (95%CI=47-84), and 69% (95%CI=55-82), respectively. CONCLUSION: RTMCE allows for quantification of dynamic changes in microcirculatory blood flow at each stage of DASE. The best parameter for detecting CAD in all stages was ß reserve.

Evaluation of blood flow reserve in left anterior descending coronary artery territory by quantitative myocardial contrast and Doppler echocardiography.

We sought to compare the feasibility and accuracy of myocardial blood flow reserve (MBFR) measured by quantitative real-time myocardial contrast echocardiography with those of coronary flow velocity reserve (CFVR) obtained by transthoracic Doppler echocardiography for detecting left anterior descending coronary artery (LAD) stenosis. We studied 71 patients who underwent adenosine stress contrast echocardiography, transthoracic Doppler echocardiography, and quantitative coronary angiography within 1 month. An index of myocardial blood flow (A x beta) was determined by quantification of peak plateau acoustic intensity (A) and microbubble replenishment velocity (beta) by contrast echocardiography. Feasibilities of qualitative analysis of myocardial perfusion, and CFVR and MBFR measurements were 98%, 83%, and 94%, respectively. Patients with LAD stenosis had lower CFVR (1.1 +/- 0.4 vs 2.7 +/- 0.8, P < .001), MBFR (1.2 +/- 0.5 vs 2.5 +/- 0.8, P < .001), and beta reserve (1.1 +/- 0.5 vs 2.4 +/- 0.6, P < .001) than those without lesion. Sensitivities, specificities, and accuracies for detecting LAD stenosis were 64%, 93%, and 80% for qualitative analysis of myocardial perfusion; 92%, 94%, and 93% for CFVR; 84%, 87%, and 86% for MBFR; and 80%, 97%, and 89% for beta reserve. In this selected study population, CFVR was the best index for detecting LAD stenosis (odds ratio = 1.78, 95% confidence interval = 1.28-2.47).

Avaliação das reservas de fluxo coronariano e miocárdico pela ecocardiografia com Doppler e com contraste no território da artéria descendente anterior / Evaluation of coronary flow reserve and myocardial flow reserve by Doppler echocardiography and myocardial contrast echocardiography in the left anterior descending coronary artery territory

Comparamos a reserva de fluxo coronariano (RFC) obtida pela ecocardiografia de perfusão miocárdica em tempo real e pelo Doppler, no território da descendente anterior (ADA) em 44 pacientes. Quantificamos a velocidade de fluxo na ADA e no miocárdio em repouso e durante infusão de adenosina e realizamos angiografia. A análise de RFC demonstrou acurácia para detecção de obstrução pelo Doppler / We compared the coronary flow reserve (CFR) taken by real time myocardial contrast echocardiography (RTMCE) and by Doppler flow in the left anterior descending coronary territory (LAD) in 44 patients. The flow velocities in the LAD and on myocardial at rest and during of adenosine infusion were measured, and angiography was performed. The analysis of CFR showed diagnostic accuracy for the detection of LAD obstruction for Doppler flow of...