Myocardial Scar Detection by Standard CT Coronary Angiography.

We have described a myocardial infarct scar identified by a standard dual source CT coronary angiography (CTCA). We were able to detect the scar during the routine coronary assessment without contrast late enhancement and without additional radiation exposure. It is therefore feasible to assess chronic scar using a standard CTCA technique.

Prevalence of coronary artery calcium scores and silent myocardial ischaemia was similar in Indian Asians and European whites in a cross-sectional study of asymptomatic subjects from a U.K. population (LOLIPOP-IPC).

BACKGROUND: Coronary heart disease (CHD) mortality is 70% higher among Indian Asians (IA) than European whites (EW), the reasons for this excess remain unexplained. Coronary artery calcification (CAC) is highly correlated with coronary plaque burden and silent myocardial ischaemia in EW; but fails to identify excess risk in IA. We hypothesised that IA have a higher prevalence of silent myocardial ischaemia compared to EW, despite similar CAC, and this may explain their excess CHD mortality. METHODS: CAC was measured for 2,369 asymptomatic men and women, aged 35 to 75 years, as part of the London Life Sciences Population (LOLIPOP) study. 518 subjects had CAC scores >100 Agatston units and of these 256 (49%) patients underwent myocardial perfusion scintigraphy (MPS). RESULTS: CAC scores were similar among IA and EW, after adjustment for conventional risk factors. MPS abnormalities were seen in 56 (22%) subjects. Presence of diabetes (P = .03) and increasing CAC (P < .001) were independent predictors for severity of silent myocardial ischaemia. Ethnicity did not influence the prevalence or the extent of silent myocardial ischaemia. CONCLUSION: MPS did not identify greater ischaemia among IA compared with EW. This appears incongruent with almost 2-fold higher risk of CHD mortality observed in IA.

Comparison between Tc-99m N-NOET and Tl-201 in the assessment of patients with known or suspected coronary artery disease.

BACKGROUND: Technetium 99m N-ethoxy-N-ethyl dithiocarbamate (N-NOET) is a new radionuclide tracer for cardiac single photon emission computed tomography (SPECT) imaging. It combines the advantageous properties of a Tc-99m agent with the redistribution characteristics of thallium 201. We directly compared the two agents in patients with known or suspected coronary artery disease. METHODS AND RESULTS: Fifty patients underwent treadmill exercise Tc-99m N-NOET and Tl-201 SPECT studies. Images were acquired at stress, redistribution, and reinjection. Segmental analysis was carried out, and direct comparisons were made with corresponding segments. A stress score index was calculated and compared with the degree of lung uptake for each patient. From the 50 patients, 2657 of 2664 exercise, redistribution, and reinjection segments (99%) were interpreted. There was excellent agreement between the two modalities (weighted kappa = 0.83). Of the patients, 24 demonstrated reversible ischemia by Tl-201 SPECT reinjection imaging, of which Tc-99m N-NOET stress-redistribution imaging correctly identified 14 (58%); this improved significantly to 20 patients (83%) ( P = .03) when a reinjection protocol was used. A higher stress score index was seen in those patients with significant lung uptake (lung-heart ratio > or =0.6) after Tc-99m N-NOET stress imaging (1.6 vs 1.3, P = .03). CONCLUSION: SPECT imaging with Tc-99m N-NOET is comparable to Tl-201 for the diagnosis of coronary artery disease. Significant lung uptake with stress Tc-99m N-NOET may also indicate the severity of disease.

Prevalence of silent myocardial ischemia in asymptomatic individuals with subclinical atherosclerosis detected by electron beam tomography.

BACKGROUND: Electron beam tomography coronary calcium imaging is an evolving technique for the early detection of coronary atherosclerosis, and recent studies have established its prognostic value in asymptomatic individuals. The relationship of coronary artery calcium scores (CAC) to obstructive coronary artery disease (CAD) has been poorly studied but is clinically relevant because it determines which individuals are likely to benefit from revascularization procedures. Hence, we prospectively evaluated the prevalence of myocardial ischemia in asymptomatic patients with cardiovascular risk factors and subclinical atherosclerosis. METHODS AND RESULTS: We studied 864 asymptomatic patients with no previous CAD but with cardiovascular risk factors, referred for electron beam tomography coronary calcium imaging to our institution over an 18-month period. From this group, 220 consecutive patients (85% men; mean age, 61 +/- 9 years; age range, 31-84 years) with moderate to severe atherosclerotic disease (coronary calcium score > or =100 Agatston units) were prospectively evaluated by technetium 99m sestamibi single photon emission computed tomography (SPECT). Patients were followed up (mean follow-up, 14 months) and data regarding their subsequent clinical management recorded. Of the 220 patients, 119 had moderate atherosclerosis (CAC score of 100-400 Agatston units) and 101 had severe atherosclerosis (CAC score > or =400 Agatston units). Abnormal SPECT findings were seen in 18% of patients with moderate atherosclerosis (n = 21) and 45% of patients with severe atherosclerosis (n = 45). Increasing severity of atherosclerosis was related to increasing ischemic burden (summed difference score = 1 +/- 0.2 for CAC score of 100-400 Agatston units and 3.2 +/- 0.5 for CAC score > or =400 Agatston units). In a multivariate linear regression model incorporating risk factors, CAC was the only predictor of silent ischemia. CONCLUSION: In comparison to previously published data, we detected a higher prevalence of silent ischemia even in patients with moderate coronary atherosclerosis (18%). This may reflect the differing risk factor profile of our patient population. When coronary calcium screening is used to preselect asymptomatic patients with cardiovascular risk factors for myocardial perfusion imaging, the optimum coronary calcium score threshold will depend on the population prevalence of risk factors and asymptomatic obstructive CAD.

Impact of revascularization and myocardial viability determined by nitrate-enhanced Tc-99m sestamibi and Tl-201 imaging on mortality and functional outcome in ischemic cardiomyopathy.

BACKGROUND: Nitrate-enhanced perfusion imaging has been shown to detect viability in dysfunctional myocardium, but nitrate-enhanced technetium 99m sestamibi has not been compared with nitrate-enhanced thallium 201. METHODS AND RESULTS: Fifty-six patients with ischemic cardiomyopathy and heart failure (New York Heart Association classes II-IV) were scheduled for revascularization. Through use of a matching 12-segment model, nitrate-enhanced Tl-201 and Tc-99m sestamibi uptake at rest was assessed by 2 sets of blinded investigators. All single photon emission computed tomography data sets were read separately. Additional exercise Tc-99m sestamibi single photon emission computed tomography was performed on a separate day. Myocardial viability was thought to be present when the tracer uptake score was less than 3 (normal, 0; absent, 4). Of the 56 patients scheduled to undergo revascularization, only 23 (41%) underwent the procedure and the remainder continued medical therapy. Functional assessment by rest echocardiography was performed at 21 +/- 8 months, and survival was determined at 40 +/- 18 months. The baseline clinical and hemodynamic parameters were similar in the revascularization (n = 23) and medical therapy (n = 33) groups. Perfusion scores with nitrate-enhanced Tl-201 and Tc-99m sestamibi were similar in dysfunctional segments. Stress Tc-99m sestamibi reversible defects predicted significant improvement in left ventricular function compared with those without defects (P <.01) after revascularization. Cox regression model showed that when at least 5 reversible segments were viable, revascularization produced greater improvements in New York Heart Association class, a better trend toward survival (P =.07 for Tl-201 and P =.06 for Tc-99m), and a significantly greater impact on reverse remodeling. CONCLUSIONS: Myocardial viability determined by nitrate-enhanced Tl-201 and myocardial viability determined by Tc-99m sestamibi are equivalent for predicting functional improvements, remodeling, and survival after revascularization in patients with ischemic cardiomyopathy.

Rapid assessment of patients with non-ST-segment elevation acute chest pain: troponins, inflammatory markers, or perfusion imaging?

BACKGROUND: Perfusion imaging during or soon after pain has been shown to provide diagnostic and prognostic information in patients with suspected angina. Measurement of troponin I (TnI) and troponin T (TnT) provides similar information but only several hours after onset of pain. The role of inflammatory markers in this setting is less clear. METHODS AND RESULTS: We prospectively studied 80 nonconsecutive patients using gated technetium 99m sestamibi single photon emission computed tomography (MIBI), TnT, TnI, C-reactive protein, IL-6, and tumor necrosis factor alpha. Of these patients, 50 (63%) had abnormal MIBI, 13 (17%) had elevated TnT, 17 (21%) had elevated TnI, and C-reactive protein, IL-6, and tumor necrosis factor alpha were raised in 46 (58%), 14 (18%), and 29 (37%), respectively. Myocardial infarction was the presenting event in 13 patients (16%), and 23 (34%) of those without index myocardial infarction sustained a cardiovascular event during follow-up. MIBI, TnT, TnI, and electrocardiogram all had similar negative predictive values for index myocardial infarction (97%, 97%, 95%, and 97%, respectively). However, only MIBI had a high negative predictive value for the prediction of subsequent events during follow-up (86%). TnT and MIBI were the only independent predictors of all events. Inflammatory markers provided no useful additional prognostic information. CONCLUSIONS: The combination of TnT and MIBI is the best model for early prediction of cardiac events in patients with acute chest pain.