Real-time Myocardial Perfusion Echocardiography Research Articles

A Sonotrombólise Promove Melhora dos Índices de Motilidade e Perfusão do Ventrículo Esquerdo após o Infarto Agudo do Miocárdio

ResumoFundamentoDemonstrou-se recentemente que a aplicação de ultrassom de alta energia com microbolhas, técnica conhecida como sonotrombólise, causa a dissolução de trombos intravasculares e aumenta a taxa de recanalização angiográfica no infarto agudo do miocárdio com supradesnivelamento do segmento ST (IAM-CSST).ObjetivoAvaliar o efeito da sonotrombólise nos índices de motilidade e perfusão miocárdicas em pacientes com IAM-CSST, utilizando a ecocardiografia com perfusão miocárdica em tempo real (EPMTR).MétodoUma centena de pacientes com IAM-CSST foram randomizados em dois grupos: Terapia (50 pacientes tratados com sonotrombólise e angioplastia coronária primária) e Controle (50 pacientes tratados com angioplastia coronária primária). Os pacientes realizaram EPMTR para analisar a fração de ejeção do ventrículo esquerdo (FEVE), o índice de escore de motilidade segmentar (IEMS) e o número de segmentos com defeito de perfusão miocárdica, 72 horas após o IAM-CSST e com 6 meses de acompanhamento. Foi considerado significativo p < 0,05.ResultadosPacientes tratados com sonotrombólise apresentaram FEVE mais alta que o grupo Controle em 72 horas (50 ± 10% vs. 44 ± 10%; p = 0,006), e essa melhora foi mantida em seis meses (53 ± 10% vs. 48 ± 12%; p = 0,008). O IEMS foi similar nos grupos Terapia e Controle em 72 horas (1,62 ± 0,39 vs. 1,75 ± 0,40; p = 0,09), mas tornou-se menor no grupo Terapia em 6 meses (1,46 ± 0,36 vs. 1,64 ± 0,44; p = 0,02). O número de segmentos com defeito de perfusão não foi diferente entre os grupos em 72 horas (5,92 ± 3,47 vs. 6,94 ± 3,39; p = 0,15), mas ficou menor no grupo Terapia em 6 meses (4,64 ± 3,31 vs. 6,57 ± 4,29; p = 0,01).ConclusãoA sonotrombólise em pacientes com IAM-CSST resulta na melhora dos índices de motilidade e perfusão ventricular ao longo do tempo.

Sonothrombolysis Improves Myocardial Dynamics and Microvascular Obstruction Preventing Left Ventricular Remodeling in Patients With ST Elevation Myocardial Infarction.

It has recently been demonstrated that high-energy diagnostic transthoracic ultrasound and intravenous microbubbles dissolve thrombi (sonothrombolysis) and increase angiographic recanalization rates in patients with ST-segment-elevation myocardial infarction. We aimed to study the effect of sonothrombolysis on the myocardial dynamics and infarct size obtained by real-time myocardial perfusion echocardiography and their value in preventing left ventricular remodeling. One hundred patients with ST-segment-elevation myocardial infarction were randomized to therapy (50 patients treated with sonothrombolysis and percutaneous coronary intervention) or control (50 patients treated with percutaneous coronary intervention only). Left ventricular volumes, ejection fraction, risk area (before treatment), myocardial perfusion defect over time (infarct size), and global longitudinal strain were determined by quantitative real-time myocardial perfusion echocardiography and speckle tracking echocardiography imaging. Risk area was similar in the control and therapy groups (19.2±10.1% versus 20.7±8.9%; P=0.56) before treatment. The therapy group presented a behavior significantly different than control group over time (P<0.001). The perfusion defect was smaller in the therapy at 48 to 72 hours even in the subgroup of patients with no recanalization at first angiography (12.9±6.5% therapy versus 18.8±9.9% control; P=0.015). The left ventricular global longitudinal strain was higher in the therapy than control immediately after percutaneous coronary intervention (14.1±4.1% versus 12.0±3.3%; P=0.012), and this difference was maintained until 6 months (17.1±3.5% versus 13.6±3.6%; P<0.001). The only predictor of left ventricular remodeling was treatment with sonothrombolysis: the control group was more likely to exhibit left ventricular remodeling with an odds ratio of 2.79 ([95% CI, 0.13-6.86]; P=0.026). Sonothrombolysis reduces microvascular obstruction and improves myocardial dynamics in patients with ST-segment-elevation myocardial infarction and is an independent predictor of left ventricular remodeling over time.

The Relationship of Capillary Blood Flow Assessments with Real Time Myocardial Perfusion Echocardiography to Invasively Derived Microvascular and Epicardial Assessments

The basis for abnormal microvascular flow responses to demand stress in coronary artery disease (CAD) is affected by resistance changes at both the epicardial stenosis level and within the downstream capillary network. We hypothesized that abnormal microvascular perfusion (MVP) responses during demand stress in patients with intermediate coronary stenoses occur when fractional flow reserve (FFR) across the epicardial stenosis is normal, because of increased microvascular resistance. In 49 coronary arteries of 41 patients with intermediate stenoses (40%-80%) who were referred for both coronary angiography and demand stress MVP assessment, invasive coronary hemodynamics were obtained across the stenosis to measure FFR, coronary flow reserve (CFR), and hyperemic microvascular resistance (HMR) during adenosine infusion. MVP in each coronary artery territory (CAT) during demand stress was evaluated by an independent expert reviewer blinded to clinical and angiographic data. Thirty-four of the 49 CATs with intermediate stenoses exhibited abnormal MVP. Although the sensitivity of MVP was high for detecting abnormal FFR (100%), FFR<0.8 was observed in only 15 of the 34 vessels that exhibited abnormal MVP (positive predictive value 44%). However, HMR was abnormal in 32 of 34 vessels (94%) with abnormal MVP (positive predictive value, 94%). Although abnormal MVP has high sensitivity for detecting abnormal FFR, MVP is frequently abnormal when FFR is normal. In a large percentage of these patients, invasive assessments of microvascular resistance are abnormal.

Shock-Wave Therapy Improves Myocardial Blood Flow Reserve in Patients with Refractory Angina: Evaluation by Real-Time Myocardial Perfusion Echocardiography

Cardiac shock-wave therapy (CSWT) has been demonstrated as an option for the treatment of patients with refractory angina (RA), promoting immediate vasodilatory effects and, in the long-term, neoangiogenic effects that would be responsible for reducing the myocardial ischemic load. The aim of this study was to determine the effects of CSWT on myocardial blood flow reserve (MBFR) assessed by quantitative real-time myocardial perfusion echocardiography in patients with RA. Fifteen patients (mean age 61.5±12.8years) with RA who underwent CSWT during nine sessions, over 3months of treatment, were prospectively studied. A total of 32 myocardial segments with ischemia were treated, while another 31 did not receive therapy because of technical limitations. Myocardial perfusion was evaluated at rest and after dipyridamole stress (0.84mg/kg) before and 6months after CSWT, using quantitative real-time myocardial perfusion echocardiography. Clinical effects were evaluated using Canadian Cardiovascular Society grading of angina and the Seattle Angina Questionnaire. The ischemic segments treated with CSWT had increased MBFR (from 1.33±0.22 to 1.74±0.29, P<.001), a benefit that was not observed in untreated ischemic segments (1.51±0.29 vs 1.54±0.28, P=.47). Patients demonstrated increased global MBFR (from 1.78±0.54 to 1.89±0.49, P=.017). Semiquantitative single-photon emission computed tomographic analysis of the treated ischemic segments revealed a score reduction from 2.10±0.87 to 1.68±1.19 (P=.024). There was improvement in Canadian Cardiovascular Society score (from 3.20±0.56 to 1.93±0.70, P<.05) and in Seattle Angina Questionnaire score (from 42.3±12.99 to 71.2±14.29, P<.05). No major cardiovascular events were recorded during follow-up. CSWT improved MBFR in ischemic segments, as demonstrated by quantitative real-time myocardial perfusion echocardiography. These results suggest that CSWT has the potential to increase myocardial blood flow, with an impact on symptoms and quality of life in patients with RA.

Allogeneic pASC transplantation in humanized pigs attenuates cardiac remodeling post-myocardial infarction.

Cell therapy repair strategies using adult mesenchymal stromal cells have shown promising evidence to prevent cardiac deterioration in rodents even in the absence of robust differentiation of the cells into cardiomyocytes. We tested whether increasing doses of porcine adipose-tissue derived mesenchymal stem cells (pASCs) increase cardiac tissue perfusion in pigs post-myocardial infarction (MI) receiving angiotensin-converting-enzyme inhibitor (ACE inhibitors) and Beta-blockers similarly to patients. Female pigs were subjected to MI induction by sponge permanent occlusion of left circumflex coronary artery (LCx) generating approximately 10% of injured LV area with minimum hemodynamic impact. We assessed tissue perfusion by real time myocardial perfusion echocardiography (RTMPE) using commercial microbubbles before and following pASCs treatment. Four weeks after the occlusion of the left circumflex artery, we transplanted placebo or pASCs (1, 2 and 4x106 cells/Kg BW) into the myocardium. The highest dose of pASCs increased myocardial vessel number and blood flow in the border (56% and 3.7-fold, respectively) and in the remote area (54% and 3.9-fold, respectively) while the non-perfused scar area decreased (up to 38%). We also found an increase of immature collagen fibers, although the increase in total tissue collagen and types I and III was similar in all groups. Our results provide evidence that pASCs-induced stimulation of tissue perfusion and accumulation of immature collagen fibers attenuates adverse remodeling post-MI beyond the normal beneficial effects associated with ACE inhibition and beta-blockade.

Prognostic value of dobutamine stress myocardial perfusion echocardiography in patients with known or suspected coronary artery disease and normal left ventricular function.

ObjectiveWe sought to determine the prognostic value of qualitative and quantitative analysis obtained by real-time myocardial perfusion echocardiography (RTMPE) in patients with known or suspected coronary artery disease (CAD).BackgroundQuantification of myocardial blood flow reserve (MBFR) in patients with CAD using RTMPE has been demonstrated to further improve accuracy over the analysis of wall motion (WM) and qualitative analysis of myocardial perfusion (QMP).MethodsFrom March 2003 to December 2008, we prospectively studied 168 patients with normal left ventricular function (LVF) who underwent dobutamine stress RTMPE. The replenishment velocity reserve (β) and MBFR were derived from RTMPE. Acute coronary events were: cardiac death, myocardial infarction and unstable angina with need for urgent coronary revascularization.ResultsDuring a median follow-up of 34 months (5 days to 6.9 years), 17 acute coronary events occurred. Abnormal β reserve in ≥2 coronary territories was the only independent predictor of events hazard ratio (HR) = 21, 95% CI = 4.5–99; p<0.001). Both, abnormal β reserve and MBFR added significant incremental value in predicting events over qualitative analysis of WM and MP (χ2 = 6.6 and χ2 = 24.6, respectively; p = 0.001 and χ2 = 6.6 and χ2 = 15.5, respectively; p = 0.012, respectively). When coronary angiographic data was added to the multivariate analysis model, β reserve remained the only predictor of events with HR of 21.0 (95% CI = 4.5–99); p<0.001.ConclusionQuantitative dobutamine stress RTMPE provides incremental prognostic information over clinical variables, qualitative analysis of WM and MP, and coronary angiography in predicting acute coronary events.

A comparison of infarct mass by cardiac magnetic resonance and real time myocardial perfusion echocardiography as predictors of major adverse cardiac events following reperfusion for ST elevation myocardial infarction

Infarct mass as assessed by myocardial-delayed enhancement imaging on cardiac magnetic resonance (CMR) and myocardial blood flow as assessed by real time myocardial perfusion echocardiography (RT-MPE) have been shown to predict adverse events following ST elevation myocardial infarction (STEMI). There has been no published comparison of quantitative assessment using these modalities as predictors of clinical outcomes to date. We compared RT-MPE with CMR for prediction of cardiac events in reperfused STEMI patients. Consecutive STEMI patients with early reperfusion were studied. RT-MPE and CMR were performed. Perfusion score indices (PSIRT-MPE and PSICMR ) were calculated [sum of segmental perfusion scores/number of segments]. CMR infarct mass (g) and RT-MPE myocardial blood flow (MBF dB/s) were quantified. Patients were followed for cardiac events (death, nonfatal MI, revascularization, angina, and heart failure). All 27 patients (age 62±14; follow-up 3.5±2.6years) had thrombolysis in myocardial infarction (TIMI) grade 3 flow of infarct vessel. Cardiac events occurred in 17 (63%). Cardiac event patients had higher PSIRT-MPE , PSICMR , infarct mass, and lower MBF. PSIRT-MPE cutoff of 0.3 had an AUC of 0.856 (82% sensitivity, 70% specificity), while a PSICMR cutoff of 0.2 had an AUC of 0.765 (76% sensitivity, 60% specificity). Infarct mass and MBF were independent predictors of cardiac events after adjusting for risk factors (hazard ratios: 20.9 [95% CI 1.8-256] P=.02 and 8.1 [95% CI 1.5-78] P=.01, respectively). Quantitative RT-MPE performed comparably to CMR for prediction of MACE in STEMI patients supporting a prognostic role for this noninvasive, bedside imaging method.

Regadenoson Stress Real-Time Myocardial Perfusion Echocardiography for Detection of Coronary Artery Disease: Feasibility and Accuracy of Two Different Ultrasound Contrast Agents.

The aim of this study was to compare the efficacy of myocardial perfusion (MP) and wall motion (WM) analysis obtained with real-time myocardial contrast echocardiography (RTMCE) and two widely used contrast agents in detecting coronary artery disease after injection of the vasodilator regadenoson. One hundred fifty patients were studied at two academic centers using regadenoson (400-μg intravenous bolus) vasodilator stress RTMCE (7.5% Optison infusion [n = 50] or 1.5% Definity infusion [n = 100]). Both MP and WM with RTMCE were analyzed at rest and after regadenoson bolus. Comparisons of WM and MP sensitivity, specificity, and accuracy were made. Quantitative angiography was performed in all patients within 1 month of the regadenoson stress study (>50% and >70% diameter stenosis was considered significant). Reviewers were blinded to all clinical and quantitative angiographic data. Rate-pressure product after regadenoson was higher in Optison than Definity patients (P = .004). Using a 50% diameter stenosis on quantitative angiography as a reference standard, overall sensitivity, specificity, and accuracy for combined WM and MP analysis were not different for both agents (Optison, 77%, 64%, and 73%; Definity, 80%, 74%, and 78%; P = NS). The sensitivity, specificity, and accuracy of WM analysis alone for Optison were 68%, 71%, and 69% compared with 60%, 72%, and 66% for Definity (P = NS). Adding MP analysis improved the sensitivity and accuracy of Definity for detecting both >50% and >70% stenoses (P < .001 vs WM), while MP analysis did not improve the sensitivity of Optison for detecting either >50 or >70% stenoses. RTMCE during regadenoson stress using either Optison or Definity is a rapid and effective method for the detection of coronary artery disease. The ability of MP imaging to improve WM accuracy may depend on the rate-pressure product achieved.

Relationship between HgbA1c and myocardial blood flow reserve in patients with type 2 diabetes mellitus: noninvasive assessment using real-time myocardial perfusion echocardiography.

To study the relationship between glycosylated hemoglobin (HgbA1c) and myocardial perfusion in type 2 diabetes mellitus (T2DM) patients, we prospectively enrolled 24 patients with known or suspected coronary artery disease (CAD) who underwent adenosine stress by real-time myocardial perfusion echocardiography (RTMPE). HgbA1c was measured at time of RTMPE. Microbubble velocity (β min−1), myocardial blood flow (MBF, mL/min/g), and myocardial blood flow reserve (MBFR) were quantified. Quantitative MCE analysis was feasible in all patients (272/384 segments, 71%). Those with HgbA1c > 7.1% had significantly lower β reserve and MBFR than those with HgbA1c ≤ 7.1% (P < 0.05). In patients with suspected CAD, there was a significant inverse correlation between MBFR and HgbA1c (r = −0.279, P = 0.01); however, in those with known CAD, this relationship was not significant (r = −0.117, P = 0.129). Using a MBFR cutoff value > 2 as normal, HgbA1c > 7.1% significantly increased the risk for abnormal MBFR, (adjusted odds ratio: 1.92, 95% CI: 1.12–3.35, P = 0.02). Optimal glycemic control is associated with preservation of MBFR as determined by RTMPE, in T2DM patients at risk for CAD.

Prognostic Value of Coronary and Microvascular Flow Reserve in Patients with Nonischemic Dilated Cardiomyopathy

Coronary and microvascular blood flow reserve have been established as important predictors of prognosis in patients with cardiovascular disease. The aim of this study was to assess the value of coronary flow velocity reserve (CFVR) and real-time myocardial perfusion echocardiography (RTMPE) for predicting events in patients with nonischemic dilated cardiomyopathy. One hundred ninety-five patients (mean age 54 ± 12 years; 66% men) with dilated cardiomyopathy (left ventricular ejection fraction < 35% and no obstructive coronary disease on invasive angiography or multidetector computed tomography) who underwent dipyridamole stress (0.84 mg/kg over 10 min) RTMPE were prospectively studied. CFVR was calculated as the ratio of hyperemic to baseline peak diastolic velocities in the distal left anterior coronary artery. The replenishment velocity (β), plateau of acoustic intensity (A(N)), and myocardial blood flow reserve were obtained from RTMPE. Mean CFVR was 2.07 ± 0.52, mean A(N) reserve was 1.05 ± 0.09, mean β reserve was 2.05 ± 0.39, and mean myocardial blood flow reserve (A(N) × β) was 2.15 ± 0.48. During a median follow-up period of 29 months, 45 patients had events (43 deaths and two urgent transplantations). Independent predictors of events were left atrial diameter (relative risk, 1.16; 95% confidence interval, 1.08-1.26; P < .001) and β reserve ≤ 2.0 (relative risk, 3.22; 95% confidence interval, 1.18-8.79; P < .001). After adjustment for β reserve, CFVR and myocardial blood flow reserve no longer had predictive value. Left atrial diameter added prognostic value over clinical factors and left ventricular ejection fraction (χ2 = 36.8-58.5, P < .001). Beta reserve added additional power to the model (χ2 = 70.2, P < .001). Increased left atrial diameter and depressed β reserve were independent predictors of cardiac death and transplantation in patients with nonischemic dilated cardiomyopathy. Beta reserve by RTMPE provided incremental predictive value beyond that provided by current known prognostic clinical and echocardiographic factors.

Head-to-Head Comparison of Dobutamine and Adenosine Stress Real-time Myocardial Perfusion Echocardiography for the Detection of Coronary Artery Disease

We sought to determine the value of dobutamine versus adenosine real-time myocardial perfusion (MP) echocardiography for detecting coronary artery disease and the value of quantitative analysis of MP over electrocardiography, wall motion, and qualitative MP. We studied 54 patients by real-time MP echocardiography and coronary angiography. Replenishment velocity (beta) and an index of myocardial blood flow (A(n)xbeta) were derived from quantitative MP. During dobutamine stress, beta (1.7 +/- 0.7 vs 2.7 +/- 1.2; P < .001) and A(n)xbeta (2.2 +/- 1.0 vs 3.5 +/- 1.6; P < .001) reserves were lower in patients with coronary artery disease. The same was observed with adenosine for beta (1.7 +/- 0.8 vs 2.5 +/- 1.1; P < .001) and A(n)xbeta (1.9 +/- 0.7 vs 3.2 +/- 1.4; P < .001) reserves. Accuracy of electrocardiography, wall motion, qualitative MP, and quantitative MP were 61%, 76%, 76%, and 80% for dobutamine and 70%, 70%, 76%, and 80% for adenosine, respectively. Quantitative MP had incremental diagnostic value over other variables during dobutamine (chi(2) 23.7-38.4; P < .001) and adenosine (chi(2) 26.7-59.4; P < .001). In conclusion, dobutamine and adenosine real-time MP echocardiography hold similar accuracy for detecting coronary artery disease. Quantitative MP provides incremental diagnostic information over other variables.

Determination of Size and Transmural Extent of Acute Myocardial Infarction by Real-time Myocardial Perfusion Echocardiography: A Comparison with Magnetic Resonance Imaging

The exact determination of acute myocardial infarction (AMI) extent is still a challenging issue. Quantitative myocardial perfusion echocardiography (MPE) with parametric imaging (PI) and gray scale (GS) has been shown to accurately measure infarcted area in animals, but not in human beings. We sought to validate MPE quantification of transmural extent and size of AMI using magnetic resonance imaging (MRI) as a gold standard. Twenty patients (12 men, 64 +/- 13 years) underwent MPE and MRI between the second and fifth day post-AMI. Infarct area and location, number of involved segments, and transmural extent in each segment were determined by PI using beta value and GS. Results were compared with late enhanced MRI. There was 99% agreement between both methods regarding the segmental location. The correlation between infarct area by MRI and GS was 0.82 (P < .001) whereas MRI and beta PI was 0.92 (P < .001). The correlation between transmural extent by MRI and GS was 0.77 (P < .001), and between MRI and beta PI was 0.93 (P < .001). There was a good correlation between MPE, in special beta PI, with MRI in measuring infarcted area and its transmural extent in patients with AMI.