Noninvasive techniques to assess myocardial ischemia in hypertensive patients.

Hypertensive patients are more affected by coronary artery disease (CAD) than normotensive patients. Currently, established techniques are able to diagnose myocardial ischemia/CAD in hypertensive patients with suspected CAD. An irrevocable role remains for exercise electrocardiogram (ECG) owing to the many parameters evaluated under physiologic conditions. However, the suboptimal specificity of a positive exercise ECG demands further examination of hypertensive patients with either myocardial single-photon emission computed tomography (SPECT) or stress echocardiography, both more specific than exercise ECG in diagnosing CAD. The high specificity of imaging techniques also makes them highly predictive of cardiac events. Additional techniques to help diagnose CAD are available. Tissue Doppler imaging, strain and other echo-derived techniques may add quantitative elements to recognize CAD in hypertensive hearts. The accuracy of MRI is improving to study myocardial function and perfusion. Positron emission tomography and multislice computed tomography, also in-built with fusion scanners, are playing roles in combining coronary angiography and myocardial function/ischemia assessment. However, no significant application of these additional techniques is available for hypertensive patients. Epicardial CAD assessed by coronary angiography remains the gold standard to decide for revascularization procedures. The presence of microcirculatory dysfunction, a symptom typical of hypertensive hearts, is opening up new areas of noninvasive diagnostic techniques for the detection of coronary flow reserve (CFR) and related myocardial ischemia. The quantification of CFR may render this parameter pivotal to deciding the need for revascularization procedures of intermediate coronary stenosis and it may become an additional gold standard in evaluating coronary vessels. Moreover, even with normal epicardial coronary arteries, microcirculation dysfunction bears prognostic stratification capabilities for hypertensive patients and it may become a promising therapeutic target in the near future.

Post-systolic shortening during dobutamine stress echocardiography predicts cardiac survival in patients with severe left ventricular dysfunction.

BACKGROUND: Patients with severe left ventricular dysfunction and myocardial viability by dobutamine stress echocardiography (DSE) or F18-fluorodeoxyglucose-single-photon emission computed tomography (FDG-SPECT), experience improved survival after coronary revascularization. Pulsed wave-tissue Doppler imaging (PW-TDI)-derived ejection phase shortening (EPS) and post-systolic shortening (PSS) velocities may help to quantify DSE. We assessed these variables in a prospective long-term follow-up. METHODS: Eighty patients (58 men, mean age 63+/-9 years) with left ventricular dysfunction (radionuclide ventriculography mean ejection fraction, 34+/-11%) underwent both DSE and FDG-SPECT for myocardial viability. Viable myocardium was improvement from rest to low dose or worsening of wall motion at peak DSE and normal perfusion, mildly reduced perfusion with FDG uptake or severely reduced or absent perfusion with increased FDG uptake (mismatch) at FDG-SPECT. EPS, PSS velocities and EPS/PSS ratio during DSE were analysed using a six-segment model. Coronary revascularization bypass grafting was performed in 62 patients. All patients completed a long-term (9-year) follow-up for cardiac death. RESULTS: The segmental prevalence of severe dyssynergy was 77%. On a patient basis myocardial viability was detected by EPS/PSS ratio (31%), FDG-SPECT (34%) and DSE (26%). A significant improvement of Kaplan-Meier survival was predicted in viable compared with nonviable revascularized patients (P < 0.01). Both EPS/PSS ratio and FDG-SPECT, compared to DSE alone, tended to allocate more accurately univariate prediction of death-free outcome (odds ratio, 2.5 and 2.7 compared with 2.1). CONCLUSIONS: TDI adds objective variables to DSE, helping to recognize viable myocardium and optimize prediction of death-free outcome in long-term follow-up, with favorable comparison with nuclear techniques.

Cost of strategies after myocardial infarction (COSTAMI): a multicentre, international, randomized trial for cost-effective discharge after uncomplicated myocardial infarction.

AIMS: Risk stratification after uncomplicated acute myocardial infarction is mostly applied by either symptom-limited post discharge exercise electrocardiography or pre-discharge submaximal exercise test. Aim of the present study was to determine if early pharmacological stress echocardiography and discharge within 24 hours of the test in cases without induced myocardial ischemia leads to lower costs and similar clinical outcome during 1 year follow up when compared to clinical evaluation and exercise electrocardiography after discharge. METHODS AND RESULTS: Four-hundred fifty-eight patients from 10 participating centers with a recent uncomplicated myocardial infarction were randomized to pharmacological stress echocardiography on day 3-5 followed by early discharge in the case of negative test result (early discharge strategy) (n=233) or clinical evaluation with hospital discharge on day 7-9 and symptom-limited post-discharge exercise electrocardiography at 2-4 weeks after myocardial infarction (usual care strategy) (n=225). At 1 year follow up there were 63 events (4 deaths, 9 non fatal reinfarctions, 50 chest pains requiring hospitalization) in patients randomized to early discharge, and 69 events (6 deaths, 13 reinfarctions, 50 chest pains requiring hospitalization) in usual care (p=ns). Total median individual costs calculated on the basis of hospitalizations, investigations and interventions during 1 year follow up were 3561 for early discharge strategy vs 3850 for usual care strategy (p<0.05). CONCLUSIONS: Early pharmacological stress echocardiography followed by early discharge in case of negative test result gives similar clinical outcome and lower costs after uncomplicated myocardial infarction than clinical evaluation and delayed post-discharge symptom-limited exercise electrocardiography.

Myocardial Doppler at rest for the identification of myocardial viability.

BACKGROUND: Echocardiography may permit the detection of a nonviable myocardium. The aim of this study was to test if resting pulsed wave-tissue Doppler imaging (PW-TDI) might yield additional markers. METHODS: Fifty patients (38 males, 12 females, mean age 63 +/- 6 years) with left ventricular dysfunction (ejection fraction 35 +/- 10%) underwent echocardiography. The posterior septum, anterior septum, lateral, inferior, anterior and posterior walls were sampled on the basal segments in the apical views at PW-TDI. The following variables and cardiac phases were tested: 1) the isovolumic contraction phase velocity, polarity or detectability, 2) the ejection phase velocity, a detectable interval between the ejection phase and aortic valve closure, or ejection phase shape, and 3) the isovolumic relaxation phase velocity or ejection velocity/post-systolic shortening ratio. From the tested PW-TDI variables, viable and nonviable patterns were assembled, taking rest-redistribution 201thallium single-photon emission computed tomography as the independent reference for myocardial viability. Patients with significant loading alterations, mitral or aortic valve disease, and arrhythmias were excluded. RESULTS: Out of 219 dyssynergic segments, viability as identified according to conventional rest echocardiographic criteria appeared in 94 (47%), as identified at PW-TDI in 116 (53%), and as identified at nuclear imaging in 105 (48%). The resting PW-TDI variables consistent with absent myocardial viability were as follows: 1) an isovolumic contraction phase velocity equal to the ejection phase velocity +/- 1 cm/s, or absent, 2) an ejection phase velocity < or = 4 cm/s, usually with a gap between the ejection phase and aortic valve closure, or any shape of ejection but the typical single phase, and 3) an isovolumic relaxation phase velocity < 5 cm/s with an ejection phase velocity/isovolumic relaxation phase velocity ratio < 0.8. The accuracy for the identification of myocardial viability was: agreement 73%, kappa 0.44 for echocardiography, and agreement 75%, kappa 0.47 for PW-TDI. CONCLUSIONS: PW-TDI nonviable patterns may be a helpful additional tool for the identification of patients without residual myocardial viability.

Predischarge exercise electrocardiogram and stress echocardiography can predict long-term clinically driven revascularization following acute myocardial infarction.

BACKGROUND: Predischarge stress testing provides suboptimal prediction of spontaneous hard events following uncomplicated acute myocardial infarction (AMI). HYPOTHESIS: This study was aimed at assessing whether soft cardiac ischemic events requiring late revascularization could be predicted more accurately. METHODS: In all, 428 patients undergoing exercise electrocardiography (ECG) and stress echocardiography (SE, 345 dobutamine and 83 dypiridamole) within 15 days of uncomplicated AMI were followed up for 425 (range 20-2220) days. Soft ischemic events (effort angina>class II [Canadian Cardiovascular Society Classification] and unstable angina) driving late (>6 months) revascularization were regarded as endpoints. RESULTS: A total of 58 events (29 effort and 29 unstable angina with subsequent 47 coronary artery bypass grafts and 11 percutaneous transluminal coronary angioplasties) occurred: 26 in patients with positive exercise ECG and 34 in patients with positive SE. Univariate predictors of revascularizations were positive exercise ECG (p = 0.0001), peak wall motion score index (WMSI) (p = 0.0009), low workload (p = 0.0018), rest WMSI (p = 0.02) and positive SE (p = 0.02). Cox multivariate analysis selected peak WMSI, positive exercise ECG, and low workload positive exercise ECG as independent predictors of late revascularizations. CONCLUSIONS: Predischarge stress testing identifies the long-term occurrence of soft ischemic events driving late revascularization after uncomplicated AMI.

Feasibility and image quality of dual-isotope SPECT using 18F-FDG and (99m)Tc-tetrofosmin after acipimox administration.

UNLABELLED: Currently, with the rapidly increasing number of patients with heart failure due to chronic coronary artery disease, the need for viability studies to guide treatment in these patients is increasing. The most accurate method for viability assessment is metabolic imaging with (18)F-FDG with PET or SPECT. To obtain excellent image quality in all patients, the (18)F-FDG studies should be performed during hyperinsulinemic euglycemic clamping. However, this approach is time-consuming and is not feasible in busy nuclear medicine laboratories. Recently, the use of a nicotinic acid derivative, acipimox, has been suggested, but limited data are available on the image quality of the (18)F-FDG studies using this approach. METHODS: We evaluated the feasibility and image quality of (18)F-FDG SPECT (with dual-isotope simultaneous acquisition (DISA) using (99m)Tc-tetrofosmin to assess perfusion) after acipimox administration in 50 nondiabetic patients. The image quality of both (18)F-FDG and (99m)Tc-tetrofosmin was assessed visually and quantitatively using myocardium-to-blood-pool (M/B) ratios as a measure of target-to-background ratio. The image quality and diagnostic value of DISA (99m)Tc-tetrofosmin SPECT was compared with standard (99m)Tc-tetrofosmin SPECT at baseline. RESULTS: After acipimox administration, the plasma levels of free fatty acids were extremely low (68 +/- 89 nmol/L). No severe side effects were observed, only paroxysmal flushing. The (18)F-FDG image quality was good in 46 patients (92%) and moderate but still interpretable in the other 4 patients (8%). The clinical information of the baseline (99m)Tc-tetrofosmin SPECT was retained in the DISA (99m)Tc-tetrofosmin SPECT images because we did observe no substantial fill-in of perfusion defects by high (18)F-FDG uptake in the same segment. CONCLUSION: Cardiac (18)F-FDG SPECT after acipimox is safe and resulted consistently in good image quality; this simple approach may be the method of choice for routine cardiac metabolic imaging.