Leah Burden

Myocardial Contrast Echocardiography for Distinguishing Ischemic From Nonischemic First-Onset Acute Heart Failure. Insights Into the Mechanism of Acute Heart Failure

Background—Distinguishing ischemic from nonischemic origin in patients presenting with acute heart failure (AHF) not resulting from acute myocardial infarction has both therapeutic and prognostic implications. The aim of the study was to assess whether myocardial contrast echocardiography (MCE) can identify underlying coronary artery disease (CAD) as the cause of AHF. Methods and Results—Fifty-two consecutive patients with AHF with no prior clinical history of CAD and no clinical evidence of acute myocardial infarction underwent resting echocardiography and MCE both at rest and after dipyridamole stress at a mean of 9±2 days after admission. All patients underwent coronary arteriography before discharge. Of the 52 patients, 22 demonstrated flow-limiting CAD (>50% luminal diameter narrowing). Sensitivity, specificity, and positive and negative predictive values of MCE for the detection of CAD were 82%, 97%, 95%, and 88%, respectively. Among clinical, ECG, biochemical, resting echocardiographic, and MCE markers of CAD, MCE was the only independent predictor of CAD (P<0.0001). Quantitative MCE demonstrated significantly (P<0.0001) lower myocardial blood flow velocity reserve in vascular territories subtended by >50% CAD (0.59±0.46) compared with patients with normal coronary arteries (1.99±1.00). However, myocardial blood flow velocity reserve in patients with no significant CAD was significantly (P=0.03) lower compared with control (2.91±0.41). Myocardial blood flow velocity reserve correlated significantly (P<0.0001) with increasing severity of CAD. Conclusions—MCE, which is a bedside technique, may be used to detect CAD in patients presenting with AHF without a prior history of CAD or evidence of acute myocardial infarction. Quantitative MCE may further risk-stratify patients with AHF but no CAD.

Independent and incremental value of stress echocardiography over clinical and stress electrocardiographic parameters for the prediction of hard cardiac events in new-onset suspected angina with no history of coronary artery disease

AIMS Recent data have shown that exercise electrocardiogram (ECG) has no incremental prognostic value over clinical and rest ECG parameters in chest pain patients without a history of coronary artery disease (CAD). The incremental prognostic value of stress echocardiography (SE) in this population is unknown. METHODS AND RESULTS Accordingly, 547 consecutive patients (68 ± 4.9 years) with chest pain but no previous history of CAD, referred for SE (exercise and dobutamine), were identified. Patients were followed up for death and acute myocardial infarction (AMI). At a median follow-up period of 28 months, there were a total of 35 hard cardiac events (5 deaths and 30 non-fatal AMI). Among the prognostic clinical, resting/stress ECG, and SE data, univariate predictors were the Framingham risk score (P = 0.025), diabetes (P = 0.06), hypercholesterolaemia (P = 0.06), stress ECG ischaemia (P = 0.044), stress heart rate (P = 0.019), and SE-determined ischaemic burden (stress-rest wall thickening score index; P < 0.001). In a multivariate model, ischaemic burden was the only independent predictor of events (P < 0.001). SE also showed incremental prognostic value over and above clinical (Framinghams risk score) and stress ECG changes in a global χ(2) model. This was true also for patients undergoing only exercise SE (n = 347). CONCLUSION SE provides both independent and incremental prognostic value for the prediction of hard cardiac events in chest pain patients without a previous history of CAD-over and above clinical, ECG, and stress ECG data.

Resting myocardial blood flow, coronary flow reserve, and contractile reserve in hibernating myocardium: implications for using resting myocardial contrast echocardiography vs. dobutamine echocardiography for the detection of hibernating myocardium

AIMS Controversy exists regarding the relative status of resting myocardial blood flow (MBF), coronary flow reserve (CFR), and contractile reserve (CR) in hibernating myocardium (HM). We hypothesized that CFR is more profoundly affected than resting MBF parameters in HM. Thus, resting MBF assessed by myocardial contrast echocardiography (MCE) will be more sensitive than CR elicited by dobutamine stress echocardiography (DSE) for the detection of HM. METHODS AND RESULTS Accordingly 27 patients with ischaemic cardiomyopathy underwent resting MCE and DSE prior to revascularisation, of which 23 patients underwent follow-up echocardiography at 179 ± 66 days after revascularization. Qualitative and quantitative MCE [contrast intensity (A, dB)], MBF (represented by blood velocity β, dB/s), and CFR (vasodilator β/rest β, β reserve) were obtained. CR was obtained during DSE. Resting contrast intensity (7.2 ± 2.3 dB) and β (0.67 ± 0.47 dB/s) were significantly (P < 0.005 and <0.01, respectively) reduced in HM vs. remote normal myocardium but significantly higher compared with non-viable segments (4.4 ± 2.3 dB and 0.43 ± 0.32 dB/s, respectively). However, CFR was significantly (0.82 ± 3.2 (P = 0.01)) lower in HM compared with normal (1.8 ± 1.02) but not significantly reduced when compared with non-viable myocardium (1.1 ± 3.3). Sensitivity for the detection of HM with qualitative and quantitative MCE were 82 and 87%, respectively, compared with 67% (P < 0.0001) by DSE with similar specificity of 55 and 67%, respectively, compared with 63% with DSE. CONCLUSION Resting MBF but not CFR distinguished HM from non-viable myocardium. Resting MCE and not DSE was more accurate for the prediction of HM.

Myocardial Contrast Echocardiography Versus Single Photon Emission Computed Tomography for Assessment of Hibernating Myocardium in Ischemic Cardiomyopathy: Preliminary Qualitative and Quantitative Results

BACKGROUND Single photon-emission computed tomography (SPECT) is widely used for the assessment of hibernating myocardium (HM). The aim of this study was to test the hypothesis that myocardial contrast echocardiography (MCE), because of its better spatial and temporal resolution, would be superior to SPECT for the detection of HM. METHODS Thirty-nine consecutive patients with symptomatic ischemic cardiomyopathy underwent rest and vasodilator SPECT and MCE. Of these, 23 survived to undergo assessment 3 months after revascularization for the recovery of left ventricular (LV) function (spontaneous recovery or dobutamine induced), which is the definition of HM. RESULTS Of the 214 dysfunctional segments, 156 segments demonstrated HM in the 23 patients, of whom 16 showed significant improvement in LV function. Logistic regression analysis showed that both qualitative and quantitative MCE were independent predictors for the detection of HM (P < .0001 vs P = .06 for qualitative MCE vs qualitative SPECT, respectively, and P < .01 vs P = .25 for all quantitative myocardial contrast echocardiographic parameters vs quantitative SPECT, respectively). Using clinical and LV functional data, SPECT, and MCE for predicting the recovery of LV function, MCE was the only independent predictor (P = .03). CONCLUSION MCE was superior to SPECT for the assessment of HM in ischemic cardiomyopathy.