Value of thallium-201 imaging in detecting adverse cardiac events after myocardial infarction and thrombolysis: a follow up of 100 consecutive patients

In vivo R1-enhancement mapping of canine myocardium using ceMRI with Gd(ABE-DTTA) in an acute ischemia-reperfusion model

PURPOSE

To demonstrate the usefulness of normalized DeltaR1 (DeltaR1(n)) mapping in myocardial tissue following the administration of the contrast agent (CA) Gd(ABE-DTTA).

MATERIALS AND METHODS

Ischemia-reperfusion experiments were carried out in 11 dogs. The method exploited the relatively long tissue lifetime of Gd(ABE-DTTA), and thus no fast R1 measurement technique was needed. Myocardial perfusion was determined with colored microspheres (MP).

RESULTS

With varying extent of ischemia, impaired wall motion (WM) and lower DeltaR1(n) values were detected in the ischemic sectors, as opposed to the nonischemic sectors where normal WM and higher DeltaR1(n) were observed. Based on the DeltaR1(n), data from the myocardial perfusion assay and the DeltaR1(n) maps were compared in the ischemic sectors. A correlation analysis of these two parameters demonstrated a significant correlation (R = 0.694, P < 0.005), validating the DeltaR1(n)-mapping method for the quantitation of ischemia. Similarly, pairwise correlations were found for the MP, DeltaR1(n), and wall thickening (WT) values in the same areas. Based on the correlation between DeltaR1(n) and MP, DeltaR1(n) maps calculated with a pixel-by-pixel resolution can be converted to similarly high-resolution myocardial perfusion maps.

CONCLUSION

These results suggest that the extent of the severity of ischemia can be quantitatively represented by DeltaR1(n) maps obtained in the presence of our CA.

Long-term outcome after primary stenting versus balloon angioplasty for acute myocardial infarction

The objective of the present prospective multicenter case-control study was to investigate the long-term clinical outcome (5 years) of primary stenting compared to primary percutaneous transluminal coronary angioplasty (PTCA) without stenting (POBA) in patients with acute myocardial infarction at 7 cardiovascular centers in Hokkaido, Japan. Forty-one patients with acute myocardial infarction treated with successful primary stenting (stent group: case) and paired with 41 matched control subjects with acute myocardial infarction treated by successful primary PTCA without stenting (POBA group: control) were analyzed. After 1 year, the stent group had a lower incidence of the combined clinical endpoint (death, rehospitalization due to congestive heart failure, nonfatal myocardial infarction, repeat angioplasty, CABG, or cerebrovascular events) compared to the POBA group (17.1% versus 39.0%, P = 0.049). After 5 years, the incidences of congestive heart failure and cardiac death were the same in both groups. However, compared to the POBA group, the stent group had a lower combined clinical endpoint (34.1% versus 61.0%, P = 0.027). The Kaplan-Meier event-free survival curves of the stent group showed a significantly lower occurrence of clinical events compared to the POBA group (P = 0.0116). Multiple logistic regression analysis of clinical events identified age > or = 69 years (P = 0.0092, odds ratio = 4.179) and stenting (P = 0.0158, odds ratio = 0.279) as explanatory factors. Compared with POBA, primary stenting for acute myocardial infarction results in a better long-term clinical outcome.

Excess recurrent cardiac events in rheumatoid arthritis patients with acute coronary syndrome

BACKGROUND

Cardiovascular mortality is increased in rheumatoid arthritis. Possible reasons include an increased incidence of ischaemic heart disease or worse outcome after acute coronary syndrome (ACS).

OBJECTIVES

To assess the outcome of ACS in rheumatoid arthritis compared with case matched controls in the context of underlying cardiac risk factors, clinical presentation, and subsequent management.

METHODS

40 patients with rheumatoid arthritis and ACS identified from coronary care admission registers between 1990 and 2000 were case matched as closely as possible for age, sex, classical cardiovascular risk factors, type and severity of ACS, and admission date (+/-3 months) with 40 controls. A standardised proforma was used for detailed case note review.

RESULTS

Age, sex, other cardiovascular risk factors, and type and severity of presenting ACS were not significantly different between cases and controls. Recurrent cardiac events were commoner in rheumatoid arthritis (23/40, 57.5%) than controls (12/40, 30%) (p = 0.013); there were 16/40 deaths in rheumatoid arthritis (40%) v 6/40 (15%) in controls (p = 0.012). Recurrent events occurred earlier in rheumatoid arthritis (log rank survival, p = 0.05). Presentation with chest pain occurred in all controls compared with 33/40 rheumatoid patients (82%) (p = 0.006); collapse occurred in one control (2.5%) v 7/40 rheumatoid patients (17.5%) (p = 0.025). Treatment during the ACS was not significantly different in the two groups.

CONCLUSIONS

Recurrent ischaemic events and death occur more often after ACS in rheumatoid arthritis. Atypical presentation is commoner in rheumatoid arthritis. There is an urgent need to develop identification and intervention strategies for ACS specific to this high risk group.

Myocardial viability assessed by dobutamine stress echocardiography predicts reduced mortality early after acute myocardial infarction: determining the risk of events after myocardial infarction (DREAM) study

OBJECTIVE

To establish further the role of dobutamine stress echocardiography (DSE) in prognostication of outcome early after acute myocardial infarction (AMI) METHODS: Consecutive patients presenting with AMI were screened for inclusion into the study. 212 stable consenting patients underwent DSE a mean (SD) of 4.8 (1.5) days after AMI. Patients were then followed up for 803 (297) days.

RESULTS

The mean (SD) resting systolic wall thickening index (SWTI) was 1.6 (0.4), 44% patients had evidence of viability at low dose, and 38% had evidence of ischaemia. During the follow up period 27 (13%) patients died and 16 (8%) had a non-fatal AMI. Independent predictors of both mortality and combined mortality and non-fatal AMI were age (hazard ratio (HR) 1.04/year, p = 0.01, and HR 1.03/year, p = 0.04, respectively) and SWTI at low dose (HR 3.6, p < 0.01, and HR 2.5, p = 0.02, respectively). Low dose DSE provided incremental information over clinical and resting left ventricular function data for predicting death and non-fatal AMI. For patients who were not revascularised SWTI at peak dose dobutamine was the only independent predictor of mortality.

CONCLUSION

DSE is a powerful predictor of outcome in stable survivors of AMI. The presence of myocardial viability has a positive impact on survival.

Prognostic value of dipyridamole SPECT imaging in low-risk patients after myocardial infarction

BACKGROUND

The prognostic value of perfusion imaging was assessed in low-risk patients after myocardial infarction (MI) and compared with clinical and angiographic variables.

METHODS AND RESULTS

Rest thallium and dipyridamole technetium 99m sestamibi single photon emission computed tomography imaging was performed in 203 (91%) low-risk patients 3 to 21 days after MI who were enrolled in a trial of low-dose warfarin sodium and aspirin. Patients were considered low risk with planned nonintervention, on the basis of an uncomplicated course after MI, negative submaximal stress electrocardiography, and the absence of significant angiographic disease requiring revascularization. During a minimum follow-up of 12 months, 69 patients (34%) had clinical events: 1 cardiac death, 7 MIs, 26 admissions for unstable angina, 18 coronary bypass grafting, and 17 angioplasty. Univariate analysis identified the extent of significant angiographic stenoses (> or =70%) and the extent of scintigraphic defect as predictive of future events. On multivariate analysis, the presence of any scintigraphic reversibility had the strongest correlation with clinical events, with better predictive value than angiographic multivessel stenoses (P =.0006 vs P =.003).

CONCLUSIONS

In the low-risk population after MI, scintigraphic reversibility remains a strong predictor of cardiac events, with greater prognostic value than angiographic data. The extent of scintigraphic reversibility was directly correlated with clinical events. Therefore scintigraphic imaging remains clinically relevant for risk stratification in the current low-risk population after MI.

Prognostic value of impaired myocardial fatty acid uptake in patients with acute myocardial infarction

Impaired cardiac fatty acid uptake, assessed by the radiolabelled fatty acid analogue beta-methyl-p-iodophenyl pentadecanoic acid (I-123-BMIPP), is observed in the myocardium following acute ischaemic events, but the long-term prognostic implication has not been established. This study aimed to determine the prognostic value of cardiac BMIPP uptake in patients with acute myocardial infarction. Following the assessment of thallium-201 and I-123-BMIPP uptake, 101 post-infarct patients were prospectively followed up with primary end points of cardiac death, heart failure and non-fatal infarction. During a mean follow-up of 28 months, three cardiac deaths, three non-fatal infarctions, 23 revascularizations and four recurrences of angina pectoris were observed. Multivariate analysis identified reduced uptake of BMIPP and perfusion, no beta-blocking treatment and greater thallium-BMIPP mismatch (i.e. larger BMIPP defect than thallium defect) as significant predictors for overall cardiac events. Prior myocardial infarction, reduced left ventricular ejection fraction and greater thallium-BMIPP mismatch were selected as independent predictors of harder cardiac events. Female patients, those with greater BMIPP defect or greater thallium-BMIPP mismatch showed worse clinical outcomes. The inclusion of BMIPP data improved the prognostic values of conventional significant predictors. In conclusion, impaired myocardial I-123-BMIPP uptake and perfusion-BMIPP mismatch are related to a high probability of fatal and non-fatal cardiac events, suggesting the aetiological relevance and prognostic value of impaired cardiac fatty acid metabolism in viable, but jeopardized, myocardium following acute myocardial infarction.

Early dipyridamole (99m)Tc-sestamibi single photon emission computed tomographic imaging 2 to 4 days after acute myocardial infarction predicts in-hospital and postdischarge cardiac events: comparison with submaximal exercise imaging

BACKGROUND

Because of its brief hemodynamic effects and minor effect on determinants of myocardial oxygen demand, vasodilator stress myocardial perfusion imaging (MPI) can be applied very early after acute myocardial infarction (AMI) for risk stratification, allowing management decisions to be made earlier and thus potentially shortening hospitalization stays, reducing costs, and preventing early cardiac events. This multicenter randomized trial compared the prognostic value of early dipyridamole MPI and standard predischarge submaximal exercise MPI in patients who presented with AMI.

METHODS AND RESULTS

Patients who presented with their first AMI (n=451) were randomized in a 3:1 ratio to undergo either both an early (day 2 to 4) dipyridamole (99m)Tc-sestamibi MPI study and a predischarge (day 6 to 12) submaximal exercise (99m)Tc-sestamibi MPI study or only the predischarge study. Multivariate predictors of in-hospital cardiac events included nuclear imaging summed stress and summed reversibility scores and peak creatine kinase. For postdischarge cardiac events, multivariate predictors in patients undergoing dipyridamole MPI included only the summed stress, reversibility, and rest imaging scores and anterior MI. For a given summed stress score, the interaction of reversibility score further improved the predictive value. Dipyridamole MPI showed better risk stratification than submaximal exercise MPI.

CONCLUSIONS

Dipyridamole MPI very early after MI predicts early and late cardiac events, with superior prognostic value compared with submaximal exercise imaging. The extent and severity of the stress defect and reversibility of the defect were the most important predictors of cardiac death and recurrent MI. This technique can allow management decisions to be made earlier with regard to AMI patients and could have important economic impact if applied widely.

Stress myocardial perfusion imaging versus echocardiography for the diagnosis and risk stratification of patients with known or suspected coronary artery disease

Stress perfusion imaging and stress echocardiography (ECHO) are both very useful for assessment of diagnosis and risk stratification of patients with coronary artery disease (CAD). Both techniques have been well validated during exercise and inotropic stress, but coronary vasodilation stress is better used in combination with perfusion imaging. The overall sensitivity for detection of CAD is slightly higher by single photon emission computed tomography (SPECT) than by two-dimensional (2D) ECHO during all stress modalities, whereas the specificity is slightly higher by ECHO, although the differences in general are not statistically significant. SPECT, however, appears to be superior to ECHO in the diagnosis of isolated circumflex stenosis, as well as for the correct identification of multivessel CAD. A substantially greater amount of information is available regarding risk stratification with SPECT than with 2D ECHO. Although the data suggest that both techniques are very useful for risk stratification of patients with stable CAD, after myocardial infarction, and for preoperative risk stratification, the risk for cardiac events is lower in the presence of a normal stress SPECT study than of a normal stress ECHO.

Use of stress echocardiography for risk assessment of patients after myocardial infarction

The main predictors of outcome after infarction (exercise capacity, ejection fraction, and extent of jeopardized myocardium) can all be identified using stress echocardiography. This review addresses the place of stress echocardiography in postinfarct risk evaluation, relative to clinical evaluation, and other technologies. The test is accurate for identification of multivessel disease and for predicting outcomes, is versatile, and can be used early after infarction.

Risk stratification after myocardial infarction in Scotland

The objective was to determine how patients are selected for invasive investigation after myocardial infarction in Scotland. Cardiologists in Scotland were surveyed by postal questionnaire asking them to detail their approach to four sample clinical scenarios. Complete responses were obtained from 82% of those surveyed. Substantial differences in practice were observed in the management of subjects with non-Q wave myocardial infarction. Of the cardiologists surveyed 40% would undertake coronary angiography irrespective of the results of non-invasive testing in a 45 year old patient, but only one would adopt the same policy in an otherwise fit 77 year old. Only 44% would perform any investigations (beyond echocardiography) in the 77 year old. A minority of respondents felt that their practice was influenced by resource limitation. Considerable variation continues to exist in the approach to risk stratification after myocardial infarction for some groups of patients. This variation may occur principally as a consequence of physician preference.