Risk stratification with pre-hospital discharge exercise technetium-99m sestamibi myocardial tomography in men after acute myocardial infarction

Impact of the Charlson Comorbidity Index score on risk prediction by single-photon emission computed tomography myocardial perfusion imaging following myocardial infarction

Background

Comorbidity is common among patients with myocardial infarction (MI). We examined whether comorbidity level modified the single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI)-based prediction of 5-year risk of MI and all-cause death in patients with MI.

Methods

This cohort study included patients with prior MI having a SPECT MPI at Aarhus University Hospital, Denmark, 1999–2011. Using nationwide registries, we obtained information on comorbidity levels (low, moderate, and severe) and outcomes. We computed risk and hazard ratios (HRs) with 95% confidence intervals (CIs) for MI and all-cause death, comparing normal (no defects) versus abnormal scan (reversible and/or fixed defects) using Cox regression adjusting for sex, age, and comorbidity level.

Results

We identified 1,192 patients with MI before SPECT MPI. The 5-year risk for patients with normal versus abnormal scans were 11.7% versus 18.3% for MI, and 8.0% versus 13.2% for all-cause death, respectively. The overall 5-year adjusted HR (aHR) of MI was 1.56 (95% CI: 1.09–2.21), 1.33 (95% CI: 0.82–2.15) with low comorbidity, 1.39 (95% CI: 0.68–2.83) with moderate comorbidity, and 2.53 (95% CI: 1.14–5.62) with severe comorbidity. Similarly, the 5-year aHR for all-cause death was 1.39 (95% CI: 0.90–2.14) overall; 2.33 (95% CI: 0.79–6.84) with low comorbidity, 2.05 (95% CI: 0.69–6.06) with moderate comorbidity, and 1.07 (95% CI: 0.64–1.80) with severe comorbidity.

Conclusion

We conclude that comorbidity level may modify the 5-year risk prediction associated with an abnormal SPECT MPI scan in patients with previous MI.

[Prognostic value of normal myocardial perfusion scintigraphy with 201Tl in post-acute myocardial infarction]

OBJECTIVE

The purpose of this work has been to determine the prognostic value of normal thallium-201 myocardial perfusion scintigraphy (MPS) in patients who had suffered myocardial infarction in the three months prior to the examination.

MATERIAL AND METHODS

A stress test followed by (201)Tl Gated SPECT was performed. A follow-up was made of 63 patients with normal perfusion scintigraphy. According to the MPS results, the patients were divided into 2 groups. Group I (n=63; 57% males, age 65±12), patients with normal MPS, and group II (n=60; 81% males, age 64±10), patients with abnormal MPS. The appearance of a new infarction or cardiac death occurring during this period (63±3 months) was analyzed. The appearance of events was related with the cardiovascular risk factors, perfusion study and ventricular function.

RESULTS

Five events occurred in group I in 4 patients: 3 new infarctions and 2 cardiac deaths. In group II, there were 18 events in 14 patients: 8 new infarctions and 10 cardiac deaths (p<0,0001). The events were related with age, time from MPS, diabetes, size of perfusion defect and post stress ventricular ejection fraction. Mean survival en group I was 108 months (103-112) and in group II 97 (88-107) (p=0,01).

CONCLUSION

Patients with normal MPS had fewer major events than patients with abnormal MPS. The size of MPS has been related with the appearance of events. A depressed post-stress left ventricular ejection fraction has a poor prognosis.

Prognostic value of stress Tc-99m tetrofosmin SPECT in patients with previous myocardial infarction: impact of scintigraphic extent of coronary artery disease

BACKGROUND

Our objective was to assess the prognostic value of the scintigraphic extent of coronary artery disease on stress technetium 99m tetrofosmin single photon emission computed tomography in patients with previous myocardial infarction.

METHODS AND RESULTS

We studied 383 patients (280 men and 103 women; mean age, 60 +/- 11 years) more than 3 months after an acute myocardial infarction by exercise bicycle or dobutamine (up to 40 mug . kg -1 . min -1 ) stress Tc-99m tetrofosmin myocardial perfusion tomography. Stress images were acquired 1 hour after stress, and rest images were acquired 24 hours after stress testing. An abnormal study was defined as one demonstrating a reversible or fixed perfusion abnormality. Myocardial segments were assigned to corresponding coronary arteries as follows: the apex, anterior wall, and anterior septum were assigned to the left anterior descending coronary artery; the posterolateral wall was assigned to the left circumflex artery; and the basal posterior septum and inferior wall were assigned to the right coronary artery. During a mean follow-up of 4.3 +/- 2.1 years, 48 cardiac events occurred (36 cardiac deaths and 12 nonfatal myocardial infarctions). Myocardial perfusion was normal in 51 patients, abnormal in a single-vessel distribution in 170 patients, and abnormal in a multivessel distribution in 162 patients. The annual cardiac event rates in these groups were 0.4%, 2.6%, and 4%, respectively. In a multivariate analysis model, independent predictors of cardiac events were diabetes mellitus (odds ratio [OR], 2.3; 95% confidence interval [CI], 1.4-4.5), history of congestive heart failure (OR, 2.7; 95% CI, 1.4-4), age (OR, 1.05; 95% CI, 1.01-1.08), and scintigraphic extent of coronary artery disease (OR, 4.2; 95% CI, 1.8-9.1).

CONCLUSION

Stress Tc-99m tetrofosmin myocardial perfusion imaging provides independent prognostic information for the risk stratification of patients with previous myocardial infarction. The event rate is directly related to the scintigraphic extent of coronary artery disease. Patients with normal perfusion have an excellent event-free survival rate.

[Value of gated-SPECT in defining the post-revascularization prognosis of patients with ischemic cardiomyopathy]

INTRODUCTION AND OBJECTIVES

Gated-SPECT simultaneously evaluates perfusion and ventricular function and could provide important prognostic information in ischemic cardiomyopathy. Our aim was to study the value of gated-SPECT performed before revascularization in a cardioischemic population to predict the outcome of revascularization.

METHODS

One hundred and ten patients who had undergone percutaneous (n = 100) or surgical revascularization were included. Patients underwent sestamibi gated-SPECT before revascularization. After revascularization, they were followed-up for at least 12 months (mean 23.7 months, maximum 44 months). We recorded deaths and a combined clinical event of death, non-fatal infarction, and hospital re-admission for cardiac reasons. We analyzed the prognostic value of clinical, angiographic, and gated-SPECT variables.

RESULTS

During follow-up, there were 14 deaths (6.4%/ year) and 36 cases of combined events (16.5%/year). Multivariate analysis showed that depressed gated-SPECT ejection fraction (threshold 0.30) was the only variable independently related to death (OR = 4.8; 95%CI, 1.6-14.6) and combined event (OR = 2.5; 95%CI, 1.2-4.8). Survival analysis showed that patients with ejection fraction < or = 0.30% had a significantly shorter period of time free of death (33 months [28-38] versus 42 months [40-44]; p = 0.002) and combined events (28 months [23-32] versus 36 months [33-39]; p = 0.007).

CONCLUSIONS

Gated-SPECT, due to the information it provides about left ventricular function, predicts the prognosis of patients after coronary revascularization.

Increased prognostic value of combined myocardial perfusion SPECT imaging and the quantification of lung Tl-201 uptake

PURPOSE

The authors wanted to identify those patients assessed by exercise SPECT in whom the quantification of lung Tl-201 uptake helps to evaluate disease prognosis.

METHODS

One hundred forty-nine patients (114 men, 35 women; 74 after myocardial infarction [MI]; mean age, 54 +/- 9 years) underwent exercise Tl-201 SPECT. The SPECT patterns were divided into normal (n = 45), fixed defects (n = 29), and inducible ischemia (n = 75). Anterior planar imaging was performed before SPECT acquisition to calculate the lung-to-heart ratio (L:H).

RESULTS

During an average follow-up of 20 +/- 9 months, eight patients had died of cardiac causes and 13 patients experienced nonfatal MIs. Among the 45 patients with normal perfusion, no cardiac event was observed and the L:H ratio was not helpful for risk stratification. In 29 patients with fixed defects, four cardiac deaths occurred (all in patients with L:H ratios >0.5; annual event rate, 21.1% for L:H ratios >0.5 compared with 0% for L:H ratios <0.5; chi-square = 4.07, P < 0.05). Among the 75 patients with ischemia, 4 died and 13 had nonfatal MIs (annual event rate, 15.4% for L:H ratios >0.5 compared with 13% for L:H ratios <0.5; P = NS).

CONCLUSIONS

These findings suggest a benign prognosis in patients with normal SPECT (regardless of the L:H ratio). Conversely, all patients with ischemia are at high risk for future cardiac events. Quantification of the Tl-201 lung uptake seems to be valuable in evaluations of disease prognosis, especially in patients with fixed defects.

[Worsening of heart failure during hospital course in myocardial infarction is a factor of poor prognosis. Apropos of a prospective cohort study of 2,507 patients hospitalized with myocardial infarction: the PRIMA study]

BACKGROUND

Worsening of heart failure in patients with myocardial infarction is seldom studied, elderly patients often are not included, and multivariate analysis is uncommon.

AIMS

The prospective PRIMA study (Prise en charge de l'Infarctus du Myocarde Aigu; management of acute myocardial infarction) sought to determine the incidence of heart failure worsening, its risk factors, and its prognostic importance in patients with myocardial infarction, regardless of age and hospital facilities, in the "real world" in a region in France, using multivariate analysis.

METHODS

Data were prospectively collected in all patients with myocardial infarction admitted in all hospitals in three departments in the Rhône-Alpes region in France between September 1, 1993 and January 31, 1995.

RESULTS

Among 2,507 patients, 33% were in Killip classes II-IV at admission. Four hundred and sixteen patients (17%) had worsening of Killip class during the first five days. In-hospital mortality (overall: 14%) increased dramatically with Killip class at admission (9% in class I; 62% in class IV) and with worsening of Killip class during the first five days (36% vs 8% if no worsening). In multivariate analysis, older age, diabetes mellitus and anterior Q-wave myocardial infarction were significant predictors of Killip class at admission and of its worsening. The significant predictors of in-hospital mortality were older age, Killip class III at admission and worsening of Killip class during the first five days.

CONCLUSION

This large, unselected cohort revealed that among patients with myocardial infarction, heart failure and its worsening are frequent, especially in the elderly, and dramatically worsen the in-hospital mortality.

Worsening of heart failure during hospital course of an unselected cohort of 2507 patients with myocardial infarction is a factor of poor prognosis: the PRIMA study. Prise en charge de l'Infarctus du Myocarde Aigu

Worsening of heart failure in patients with myocardial infarction is seldom studied, elderly patients often are not included, and multivariate analysis is uncommon. The prospective PRIMA study (Prise en charge de l'Infarctus du Myocarde Aigu; management of acute myocardial infarction) sought to determine the incidence of worsening heart failure, its risk factors, and its prognostic importance in patients with myocardial infarction, regardless of age and hospital facilities, in the 'real world' in a region in France, using multivariate analysis. Data were prospectively collected in all patients with myocardial infarction admitted in all hospitals in three departments in the Rhône--Alpes region in France between 1 September 1993 and 31 January 1995. Among the 2507 patients included, 33% were in Killip classes II--IV at admission. After exclusion of patients with admission Killip class IV, 416 patients (17% of the cohort, 24% of women and 14% of men) had worsening of Killip class during the first 5 days. In-hospital mortality (overall, 14%) increased dramatically with Killip class at admission (9% in class I, 62% in class IV) and with worsening of Killip class during the first 5 days (36.5 vs. 8.5% if no worsening). In multivariate analysis, older age, diabetes mellitus and anterior Q-wave myocardial infarction were significant predictors of Killip class at admission and of its worsening; Killip class >I at admission was a significant predictor of Killip-class worsening. The significant predictors of in-hospital mortality were older age, Killip class III at admission and worsening of Killip class during the first 5 days. This large, unselected cohort revealed that, among patients with myocardial infarction, heart failure and its worsening are frequent, especially in the elderly, and dramatically worsen the in-hospital mortality.

Prognostic value of stress-gated Tc-99m sestamibi SPECT after acute myocardial infarction

Stress-gated technetium-99m (Tc-99 m) sestamibi single-photon emission computed tomography (SPECT) is used to risk stratify patients after acute myocardial infarction (AMI). In clinical practice, results of this test are used primarily to identify patients with myocardial ischemia for intervention. The value of this test to risk stratify patients with AMI not at high ischemic risk has not been addressed. More than 1-year follow-up was undertaken in 124 patients who underwent predischarge gated Tc-99m sestamibi SPECT studies and who did not undergo subsequent revascularization. Clinical variables and test-derived variables were evaluated to predict cardiac death, recurrent AMI, and hospitalization for unstable angina, congestive heart failure, or coronary revascularization. Independent predictors by multivariate analysis for cardiac death or recurrent AMI were a history of prior AMI (relative risk [RR] = 5.32, confidence interval [CI] 2.17 to 12.96), a low exercise capacity (RR = 6.84, CI 1.99 to 23.48), and left ventricular (LV) ejection fraction (EF) <40% (RR = 2.63, CI 1.04 to 6.38). The incidence of cardiac death or recurrent AMI was 29.8% in patients with a low exercise capacity versus 4.5% in those with good exercise capacity, and 38.1% in patients with LVEF <40% versus 9.4% in those with LVEF >40%. Independent predictors of cardiac death, AMI, or hospitalization for unstable angina, congestive heart failure, or revascularization were a history of prior AMI (RR = 2.24, CI 1.11 to 4.50) and LVEF <40% (RR = 3.13, CI 1.64 to 5.95). Among patients followed after AMI without revascularization Tc-99m sestamibi SPECT can identify a high-risk subset. The strongest independent predictors are poor exercise capacity and LVEF < 40%.

Increased prognostic value of combined myocardial perfusion imaging and exercise electrocardiography in patients with coronary artery disease

BACKGROUND

Myocardial perfusion imaging (MPI) with technetium-99m-labeled sestamibi and exercise electrocardiography (EECG) are widely used for risk stratification of patients with known or suspected coronary artery disease (CAD). However, no large-scale studies have addressed the prognostic power of the combined information from these diagnostic tools.

METHODS AND RESULTS

We studied 697 consecutive patients who underwent a 2-day Tc-99m sestamibi cardiac perfusion imaging protocol. The EECG was performed on a bicycle ergometer by symptom-limited exercise. Causes of death were obtained from death certificates. Univariate survival analyses were performed with a Kaplan-Meier estimate and a corresponding log-rank test. A multivariate Cox proportional hazards model was applied to test for potential predictor covariates obtained from hospital records. The predominant risk factors of cardiac death were fixed perfusion defects (relative risk, 2.55; range, 1.43 to 4.55) and an impaired circulatory exercise response (relative risk, 3.26; range, 1.74 to 6.08). The major prognostic information of MPI was the ability to detect patients with a definitively low risk. Patients with impaired circulatory response to exercise test and fixed perfusion defects were at a very high risk.

CONCLUSION

The combined results of MPI and EECG provide substantial information on the long-term risk of cardiac death in patients with suspected CAD.

Pretest probability assessment for selective rest sestamibi scans in stable chest pain patients

The objective of this study was to determine whether pretest probability assessments permit more selective testing of chest pain patients with technetium-99m sestamibi scanning. Pretest probabilities of cardiac ischemia were measured both objectively (Acute Cardiac Ischemia Time-Insensitive Predictive Instrument [ACI-TIPI]) and subjectively (physician's estimate of the probability of unstable angina). Two groups were defined: patients whose postsestamibi scan led to a "downgrade" of the intensity of monitoring and those that resulted in no change in monitoring intensity. Sixty-five patients met study criteria; 25 had a disposition downgrade and 40 had no change. Pretest ACI-TIPI scores were similar in the two groups (29% +/- 18% versus 27% +/- 11%, mean +/- standard deviation; P = .95) as were the physician's assessment of unstable angina (39% +/- 22% versus 40% +/- 24%; P = .75). Objective or subjective pretest probabilities are not significantly different in patients who are likely to have their disposition altered by sestamibi scanning.

Cost effectiveness of early discharge after uncomplicated acute myocardial infarction

BACKGROUND

Reducing the length of hospitalizations can reduce short-term costs, but there are few data on the long-term clinical and economic consequences of early discharge.

METHODS

Using data from the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-1) trial, we identified 22,361 patients with acute myocardial infarction who had an uncomplicated course for 72 hours after thrombolysis. Then, using a decision-analytic model, we examined the cost effectiveness of an additional day of hospitalization in this group. We defined incremental survival attributable to another day of monitored hospitalization, using Kaplan-Meier estimates to determine the rate of resuscitation after cardiac arrest between 72 and 96 hours. Lifetime survival curves for each group in the decision-analytic model were estimated from empirical one-year survival data from GUSTO-1. The costs of key hospital resources (e.g., room and monitoring) were derived from data in the GUSTO-1 cost-effectiveness analysis.

RESULTS

Of the patients with an uncomplicated course within 72 hours after thrombolysis, 16 had ventricular arrhythmias during the next 24 hours; 13 of these patients (81 percent) survived for at least 24 hours. On average, another 0.006 year of life per patient could be saved by keeping patients with an uncomplicated course in the hospital another day. At a cost of $624 for hospital and physicians' services, extending the hospital stay by another day would cost $105,629 per year of life saved. In sensitivity analyses, it was found that a fourth day of hospitalization would be economically attractive only if its cost could be reduced by more than 50 percent or if a high-risk subgroup could be identified in which the estimated survival benefit would be doubled.

CONCLUSIONS

Hospitalization of patients with uncomplicated myocardial infarction beyond three days after thrombolysis is economically unattractive by conventional standards.

Technetium-99m labeled myocardial perfusion imaging agents

99mTc labeled myocardial perfusion tracers have significantly advanced the field of noninvasive diagnostic evaluation and risk stratification of patients with known or suspected coronary artery disease by providing comprehensive information about myocardial perfusion and function from a single study. Of various currently available invasive and noninvasive test modalities, myocardial perfusion imaging provides the most powerful prognostic information that is incremental to the information obtained from invasive evaluation. Future research should focus on the development of perfusion tracers that linearly track myocardial blood flow over a wide range and have minimal splanchnic uptake. Availability of an effective attenuation and scatter correction program would further eliminate some of the current limitations of this technique.

Technetium Tc 99m sestamibi myocardial perfusion imaging: current role for evaluation of prognosis

Like 201Tl imaging, technetium Tc 99m sestamibi (MIBI) myocardial imaging can be used with exercise and pharmacologic testing to assess the presence of coronary artery disease. An increasing body of literature indicates that MIBI can also be used to assess risk of future cardiac events such as myocardial infarction or death. This article summarizes the current status of MIBI imaging for evaluating prognosis in patients with known or suspected coronary artery disease.