The electrocardiogram predicts one-year outcome of patients with unstable angina and non-Q wave myocardial infarction: results of the TIMI III Registry ECG Ancillary Study. Thrombolysis in Myocardial Ischemia

Usefulness of hospital admission risk stratification for predicting nonfatal acute myocardial infarction or death six months later in unstable angina pectoris. RESCATE Study Group. Resources Used in Acute Coronary Syndromes and Delays in Treatment

The aim of this study was to assess the clinical course of unstable angina and the prognostic value of clinical and electrocardiographic variables measured during admission in a prospective, multicenter cohort study with 6-month follow-up. The population corresponds to 4 general teaching hospitals in Catalonia, Spain. The clinical course was analyzed in 839 consecutive patients aged up to 80 years with primary unstable angina, without myocardial infarction or previous coronary bypass. The main outcome measures were cardiac mortality and nonfatal myocardial infarction. Patients involved in the present analysis belonged to the Resources Used in Acute Coronary Syndromes and Delays in Treatment (RESCATE) study. Six-month overall mortality, cardiac mortality, and nonfatal myocardial infarction rates were 4.6%, 4.1%, and 3.9%, respectively. Six-month cardiac mortality or myocardial infarction rate did not differ among clinical forms of presentation. Peripheral artery disease (RR 3.5, 95% confidence interval [CI] 1.88 to 6.50, p = 0.0001), ST-T-wave electrocardiographic changes on admission (RR 2.22, 95% CI 1.13 to 4.36, p = 0.0203), and age >65 years (RR 1.74, 95% CI 1.04 to 2.91, p = 0.0356) independently predicted 6-month cardiac mortality or nonfatal myocardial infarction. Their positive predictive values were 21%, 10%, and 11%, respectively, whereas their negative predictive value was > or = 93% in all cases. Prevalences were 9%, 70%, and 41%, respectively. In this prospective study, patients with unstable angina without prior myocardial infarction have a relatively low, although not negligible, 6-month severe complication rate. Stratification risk can easily be established with clinical and electrocardiographic characteristics measured during admission. Their absence almost rules out future adverse events, while their presence does not necessarily imply bad prognosis.

Evaluation of a Rapid Whole Blood ELISA for Quantification of Troponin I in Patients with Acute Chest Pain

Background: Troponin I (cTnI) provides important prognostic information in patients with chest pain. We wished to evaluate a rapid, whole-blood analyzer for quantitative point-of-care testing.

Methods: A quantitative point-of-care test system (Stratus CS®; Dade-Behring) for cTnI with an incorporated centrifuge was evaluated in 412 patients with chest pain less than 12 h.

Results: Results were available within 15 min. CVs were 4.5% at 0.1 μg/L, 4.2% at 0.25 μg/L, and 6.5% at 0.82 μg/L. The detection limit was 0.01 μg/L. The 97.5% percentile in a healthy population was 0.08 μg/L. Based on ROC curve analysis, a threshold of 0.15 μg/L was calculated for the detection of acute myocardial infarction (AMI). With it, sensitivity for the detection of patients with AMI (n = 62) was 63% at arrival and 98% after 4 h (Stratus II®, 48% and 85%, respectively; P <0.01). In 42% of patients with unstable angina (n = 121), cTnI was ≥0.08 μg/L (Stratus II, 28%; P <0.01). During 30 days, death or AMI occurred in 25.5% of these cTnI-positive vs 2.9% of cTnI-negative patients (Stratus II, 29.4% vs 5.8%).

Conclusion: The Stratus CS provided better analytical performance and comparable or better prognostic information than the Stratus II.

The Organization to Assess Strategies for Ischemic Syndromes (OASIS) registry in patients with unstable angina

Clinical approaches to the prevention of the potentially catastrophic consequences of coronary ischemic phenomena such as unstable angina and suspected non-Q-wave myocardial infarction (MI) differ across the world. In addition to prevailing physician beliefs in different societies, the level of access to catheterization laboratories largely determines whether an interventionist or conservative strategy is adopted. The Organization to Assess Strategies for Ischemic Syndromes (OASIS)--a prospective registry of approximately 8,000 patients with acute myocardial ischemia with no ST elevation, treated in 95 hospitals across 6 countries--furnished a unique window into regional differences in clinical management and the frequency and timing of invasive procedures (i.e., angiography, percutaneous transluminal coronary angioplasty [PTCA], and coronary artery bypass graft [CABG] surgery), as well as the outcomes of these trends. At 6 months after symptom onset, patients in the United States and Brazil, where the catheterization laboratory facilities are more accessible, underwent significantly (p <0.001) more angiography (69.4%), PTCA (23.6%), and CABG (25.2%) than in Canada and Australia, where the corresponding rates were 48.4%, 17.0%, and 16.8% (p <0.001), respectively; and in Hungary and Poland, where the respective rates were 23.5%, 5.8%, and 10.9% (p <0.001). This relatively aggressive approach led at 6 months to a more substantial decrease in refractory angina in the United States and Brazil than in Canada and Australia (20.4% vs 13.9%; p <0.001), but no improvement in rates of cardiovascular mortality and MI (10.5% versus 10.5%; p = 0.36). There was a significant (p < or = 0.012) increase in stroke, (1.9% vs 1.3%; p = 0.010) and major bleeding (1.9% vs 1.1%; p = 0.009) events. Furthermore, an inverse correlation emerged between baseline cardiovascular risk status and frequency of angiography and PTCA interventions preferentially for low-risk compared with high-risk patients. In concert with findings from other recent randomized trials, the OASIS Registry data suggest that although there are fewer hospital readmissions for unstable angina, there is a trend toward increased rates of death, MI, and stroke. These data urge a cautious approach to the use of invasive procedures in patients with unstable angina unless future trials demonstrate a clear benefit with an aggressive approach.

Four-year survival of patients with acute coronary syndromes without ST-segment elevation and prognostic significance of 0.5-mm ST-segment depression

We prospectively evaluated all patients admitted to our coronary care unit during 1993 with ischemic chest pain but without ST-segment elevation on the presenting electrocardiogram, and determined the influence of the extent of ST-segment depression, measured using calipers and blinded to the outcome, on 4-year survival. The presenting symptoms of 367 patients (mean age 64 years) were coded according to the Braunwald classification, 86% being in class IIIB (primary unstable angina with rest angina within 48 hours) and 7.4% in class IIIC (postinfarction angina). Thirty-two patients (8.6%) had myocardial infarction at presentation (defined as a creatine kinase level exceeding twice the reference range within 18 hours). During hospitalization 97% of patients received aspirin, 67% received intravenous heparin, 37% underwent angiography, and 35% underwent revascularization. The vital status of 99% of the patients was determined after a median of 52 months (interquartile range 48 to 55). At follow-up, 88% of patients were taking aspirin, 45% were taking beta blockers, and 50% had undergone revascularization. The survival rate was 70% in patients with > or = 0.5-mm ST-segment depression (53%, 77%, and 82% survival for > or = 2-, 1-, and 0.5-mm ST-segment depression, respectively; p <0.0001). Patients with a normal electrocardiogram had a greater survival rate (94%) than that of patients with 0.5-mm ST-segment depression (82%, p = 0.020), but not significantly different from that of patients with T-wave inversion (84%, p = NS). Independent predictors of mortality (odds ratio [95% confidence interval]) were: age in yearly increments (1.05 [1.03 to 1.06], p = 0.003), revascularization during follow-up (0.40 [0.29 to 0.56], p = 0.006), pulmonary edema (3.45 [2.19 to 5.45], p = 0.007), and ST-segment depression (1.37 [1.20 to 1.55], p = 0.015). Thus, ST-segment depression of > or = 0.5 mm predicts 4-year survival in patients with acute ischemic syndromes.

Incorporating platelet glycoprotein IIb/IIIa inhibition in critical pathways: unstable angina/non-ST-segment elevation myocardial infarction

Platelet glycoprotein (GP) IIb/IIIa inhibitors have been shown to be effective in reducing thrombotic events in patients with acute coronary syndromes undergoing percutaneous coronary intervention (PCI) and when used as medical therapy in patients with unstable angina/non-ST-segment elevation myocardial infarction (MI). Recent findings include dramatic preventive benefits in the setting of coronary stent deployment and a significant long-term preventive effect on mortality. The benefits of GP IIb/IIIa receptor inhibition suggest the utility of adopting routine use of these agents in critical pathways of unstable angina/non-ST-segment elevation MI and PCI. Because cost constraints may limit use of these agents, however, targeting treatment based on patient risk assessment may be warranted.

Impact of troponins on the evaluation and treatment of patients with acute coronary syndromes

Cardiac troponins possess superior sensitivity and specificity for the detection of cardiac injury. They can be used successfully to replace measurements of MB isoenzyme of creatine kinase or lactate dehydrogenase for the retrospective diagnosis of myocardial infarction. Measurement of these proteins confers powerful prognostic information that can be used to triage patients. An increasing body of data suggests that measurement of troponin proteins can be useful to guide therapeutic decisions in patients with acute coronary artery syndromes, especially regarding treatment with low-molecular-weight heparin or IIB/IIIA inhibitors. The absence of troponins in the circulation does not necessarily indicate the absence of coronary artery disease. With current assays, a significant diagnostic difference does not appear to exist between cardiac troponin I and T in patients with acute coronary artery syndromes.

Comparison based on age of baseline electrocardiographic abnormalities in non-Q-wave myocardial infarction. VANQWISH Trial Research Investigators. Veterans Affairs Non-Q-Wave Infarction Strategies In-Hospital

OBJECTIVE

To compare the incidence of electrocardiographic abnormalities between older (age > or = 70 years) and younger patients presenting with acute non-Q-wave myocardial infarction.

DESIGN

Retrospective review of qualifying electrocardiograms in 918 patients enrolled in the multicenter Veterans Affairs Non-Q-Wave Infarction Strategies In-Hospital (VANQWISH) study.

SETTING

Seventeen Department of Veterans Affairs medical centers.

PARTICIPANTS

A total of 918 patients (224 > or = 70 years old) with acute non-Q-wave myocardial infarction.

MEASUREMENTS

Comparison of electrocardiograms in patients aged > or = 70 years and younger patients for presence of left ventriculary hypertrophy, widened QRS complex, ST and T wave abnormalities, rhythm other than sinus, heart rate > or = 80 beats/minute, and location of acute non-Q-wave myocardial infarction.

RESULTS

Left ventricular hypertrophy and ST depression > or = 1 mm were significantly more frequent in older than in younger patients.

CONCLUSIONS

Older patients presenting with non-Q-wave myocardial infarction have a greater incidence of left ventricular hypertrophy and ST depression on their electrocardiograms than younger patients. Both of these electrocardiographic findings have previously been associated with increased risk of death and recurrent myocardial infarction and may help account for the worse prognosis of non-Q-wave myocardial infarction in older patients.

Interesting cases from the University of Texas Medical Branch

This article discusses the cases for four patients with unstable angina. The first case is an example of the "high-risk" patient with widespread ECG changes, heart failure, and enzymatic elevations during an episode of chest pain. The second patient illustrates an unusual cause of unstable angina in a young women. The third patient had a large thrombus visible on angiography and management strategies for dealing with intracoronary thrombus are discussed. The final patient had an extensive past cardiac history with two prior coronary artery bypass operations and we discuss the recent advances made in the treatment of degenerative vein graft disease.

Relative contributions of a single-admission 12-lead electrocardiogram and early 24-hour continuous electrocardiographic monitoring for early risk stratification in patients with unstable coronary artery disease

Patients with unstable coronary syndromes are a heterogeneous group with varying degrees of ischemia and prognosis. The present study compares the prognostic value of a standard electrocardiogram (ECG) obtained at admission to the hospital with the information from 24-hour continuous electrocardiographic monitoring obtained immediately after admission. The admission ECGs and 24 hours of vectorcardiographic (VCG) monitoring from 308 patients admitted with unstable coronary artery disease were analyzed centrally regarding standard electrocardiographic ST-T changes, ST-vector magnitude (ST-VM), and ST change vector magnitude episodes. End points were death, acute myocardial infarction, and refractory angina pectoris within a 30-day follow-up period. ST-VM episodes (> or = 50 microV for > or = 1 minute) during VCG monitoring was the only independent predictor of death or acute myocardial infarction by multivariate analysis. ST-VM episodes during vectorcardiography was associated with a relative risk of 12.7 for having a cardiac event, hypertension was associated with a relative risk of 1.7, and ST depression on the admission ECG was associated with a relative risk of 5.7. Patients with ST depression at admission had an event rate (death or acute myocardial infarction) of 17% at 30-day follow-up. Patients without ST depression could further be risk stratified by 24 hours of VCG monitoring into a subgroup with ST-VM episodes at similar (8%) risk and a subgroup without ST-VM episodes at low (1%) risk (p = 0.00005). Continuous VCG monitoring provides important information for evaluating patients with unstable coronary artery disease. It is recommended that patients not initially estimated at high risk based on the admission ECG are referred for 24 hours of VCG monitoring for further risk stratification.

The role of cardiac troponin-I (cTnI) in risk stratification of patients with unstable coronary artery disease

In patients with chest pain at rest but no ST-segment elevation on the electrocardiogram, the diagnoses of unstable angina and non-Q-wave myocardial infarction (MI) are usually considered together because they cannot be differentiated clinically or angiographically. Since the extent of myocardial necrosis is an important determinant of the risk of death, it is important to identify serum markers with which to predict prognosis, in order to initiate appropriate medical treatment and/or invasive procedures in these patients. Cardiac troponin-I (cTnI), one of the subunits of the troponin regulatory complex, binds to actin and inhibits interactions between actin and myosin. The presence of elevated cTnI in serum is a significant prognostic indicator in patients with unstable angina and non-Q wave MI. Its independent prognostic potential persists even after adjustment for independent baseline variables known to be significantly associated with an increased risk of cardiac events. The use of cTnI in the triage of patients with unstable coronary disease may identify those at greater risk for adverse cardiac events.

Admission standard electrocardiogram for early risk stratification in patients with unstable coronary artery disease not eligible for acute revascularization therapy: a TRIM substudy. ThRombin Inhibition in Myocardial Infarction

OBJECTIVES

The purpose of this study was to determine the prognostic capacity of a single electrocardiogram (ECG) obtained early after admission to the hospital in patients suspected of non-Q-wave myocardial infarction and unstable angina pectoris.

METHODS

Six hundred twenty-nine patients from the TRIM study were included. The patients were divided into subgroups on the basis of ST-segment changes in the inclusion ECG. Death, acute myocardial infarction, or refractory angina (despite treatment) were registered during a follow-up period of 30 days.

RESULTS

Patients with ST depression had a significantly higher event rate compared with patients with other ECG changes or with normal ECG results. The difference in event rates between patients with ST depression and patients without ST depression regarding the composite of death and acute myocardial infarction was highly significant (P =.0008). A significant association between the magnitude of the ST-segment depression (in millimeters) and the risk of cardiac events was also demonstrated. Multivariate analysis proved ST depression early after admission to be an independent predictor of high risk.

CONCLUSION

In patients with unstable coronary artery disease, ST-segment depression at admission is a strong predictor of early (30 days) cardiac events and the extent of ST depression carries important prognostic information as well.

The outcome of patients with a first non-Q wave acute myocardial infarction presenting with ST segment depression, ST segment elevation, or no ST deviations on the admission electrocardiogram

We evaluated the prognosis of patients with a first non-Q wave myocardial infarction according to their admission electrocardiogram. Hospital and 1-year mortality rates in patients with ST elevation (15%, and 21% respectively) and ST depression (17%, and 27% respectively) were similar and significantly higher than in patients with no ST changes (3%, and 10% respectively). Likewise, the adjusted hospital and 1-year mortality risks of patients with ST elevation or depression were comparable but higher than the corresponding mortality risk of patients with no ST deviations. The cumulative 5-year mortality rate was highest among patients with ST segment depression (51%) compared to patients with ST elevation (34%) or no ST deviation (21%), (p<0.001 for both comparisons). The adjusted 5-year mortality risk of patients with ST depression was higher (HR: 1.83, 95% C.I., 1.17-2.83) compared to patients with baseline ST elevation (HR-1.33, 95% C.I., 0.83-2.12) or patients with no ST changes (reference group). Patients with baseline ST segment elevation and coexistent ST segment depression in other electrocardiogram leads, had a higher in-hospital mortality rate (19%) compared to counterparts without concomitant ST depression (10%) and a tendency for higher in-hospital mortality risk but not for subsequent 1- and 5-year mortality risks.

CONCLUSIONS

Patients with a first non-Q wave MI with ST elevation or depression on admission have similar hospital and 1-year mortality risk, but the long-term mortality risk is higher among patients with ST segment depression. Patients with ST elevation and concomitant ST segment depression are at increased risk for mortality during the index hospitalization.

Very early risk stratification using combined ECG and biochemical assessment in patients with unstable coronary artery disease (A thrombin inhibition in myocardial ischemia [TRIM] substudy). The TRIM Study Group

BACKGROUND

The diagnostic capability of troponin T (TnT), troponin I (TnI), myoglobin, and creatine kinase (CK)-MB mass for detection of myocardial injury seems evident. Newer studies have found these sensitive markers to carry independent prognostic information in patients with unstable coronary artery disease as well. ST-segment depression in the admission ECG is known to be an important indicator of poor outcome in these patients. The present study investigates the prognostic capacities of the ECG in combination with biochemical admission measurements in 516 patients admitted to hospital with unstable coronary artery disease.

METHODS AND RESULTS

Baseline ECG recordings and blood samples were collected for central analysis. The patients were followed up for 30 days, and predefined end points, ie, death, myocardial infarction, and refractory angina, were registered as end points. By univariate analysis, ST-segment depression, inverted T waves in >/=5 leads, TnT >/=0.1 microg/L, TnI >/=0.5 microg/L, myoglobin >/=40 microg/L, female sex, and age >/=65 years were predictors of death and myocardial infarction at 30 days. By multivariate analysis, female sex, ST-segment depression at randomization, or inverted T-waves in >/=5 leads were the only independent predictors of death or myocardial infarction. On the basis of baseline ECG ST-T changes and CK-MB mass/TnT/TnI/myoglobin levels, the patients were divided into 3 subgroups at high (14% event rate), intermediate (6%), and low (3%) risk of early death/myocardial infarction.

CONCLUSIONS

The present study found the combination of baseline values of TnT, TnI, CK-MB mass, and ST-T changes in the ECG to be effective for early risk stratification in patients with unstable coronary artery disease.

Variations between countries in invasive cardiac procedures and outcomes in patients with suspected unstable angina or myocardial infarction without initial ST elevation. OASIS (Organisation to Assess Strategies for Ischaemic Syndromes) Registry Investigators

BACKGROUND

There are wide variations between countries in the use of invasive cardiac catheterisation and revascularisation procedures for patients with acute ischaemic syndromes. We studied the relation between rates of such procedures and rates of cardiovascular death, myocardial infarction, stroke, refractory angina, and major bleeding in a prospective, registry-based study in six countries with widely varying intervention rates.

METHODS

7987 consecutive patients presenting with unstable angina or suspected myocardial infarction without ST-segment elevation were recruited prospectively from 95 hospitals in six countries and followed up for 6 months.

FINDINGS

The rates of all procedures were highest in patients in Brazil and the USA, intermediate in Canada and Australia, and lowest in Hungary and Poland. There were no significant differences in rates of cardiovascular death or myocardial infarction among these countries (4.7% overall [range 3.7-5.6] at 7 days; 11% overall [9-12] at 6 months). For the countries with the highest rates of invasive procedures (59%) versus the rest (21%) there was no difference in rate of cardiovascular death or myocardial infarction (adjusted odds ratio 0.88 at 7 days and 1.0 at 6 months). Rates of stroke were higher in Brazil and the USA than in the countries with lower intervention rates (adjusted odds ratio at 7 days 3.0, p=0.012; at 6 months 1.8, p=0.004) but rates of refractory angina at 7 days (0.7, p<0.001) and readmission for unstable angina at 6 months were lower (0.70, 0.63; both p<0.001). Comparison of results for hospitals without cardiac-catheterisation facilities and for those with such facilities gave adjusted odds ratios for cardiovascular death, myocardial infarction, or stroke at 6 months of 0.83 (10.6% vs 12.5%, p=0.05) and for refractory angina of 1.25 (19.3% vs 16.1%, p=0.09).

INTERPRETATION

Higher rates of invasive and revascularisation procedures were associated with lower rates of refractory angina or readmission for unstable angina, no apparent reduction in cardiovascular death or myocardial infarction, but with higher rates of stroke. Randomised trials should assess the relative impact of conservative and more aggressive approaches to invasive cardiac procedures and revascularisations in patients with unstable angina.

Differences between local investigator and core laboratory interpretation of the admission electrocardiogram in patients with unstable angina pectoris or non-Q-wave myocardial infarction (a Thrombin Inhibition in Myocardial Ischemia [TRIM] substudy)

The present study compares the on-site interpretation of an admission electrocardiogram (ECG) with core laboratory results in a large, multicenter trial of 516 patients diagnosed with unstable angina pectoris or non-Q-wave myocardial infarction. The local investigators evaluated the admission ECG regarding ST-T changes before the ECGs were sent to the core laboratory for blinded interpretation. The strength of agreement between the observations was described by kappa statistics. There was a poor agreement regarding identification of ST-segment elevation, with 17 patients identified by the local investigator versus 92 by the core laboratory (kappa = 0.05). There was a fair agreement on ST-segment depression with 158 patients diagnosed on-site versus 64 by the core laboratory (kappa = 0.38). Identification of T-wave inversion demonstrated good agreement with 306 patients diagnosed on-site versus 280 by the core laboratory (kappa = 0.63). A moderate agreement regarding identification of a normal ECG was found with 101 patients on-site versus 135 in the core laboratory (kappa = 0.42). Independent variables, including peak creatine kinase-MB and 30-day outcome, were more closely related to core laboratory results than the local investigator's interpretation of the admission ECG. Thus, in the present study, considerable differences were demonstrated between the on-site interpretation of the admission ECG and the blinded evaluation performed in the core laboratory regarding relatively simple electrocardiographic variables. The results suggest that more widespread use of independent evaluation of clinical data should be incorporated in future clinical trials.

Electrocardiographic and clinical predictors of acute myocardial infarction in patients with unstable angina pectoris

Among patients with unstable angina pectoris (UAP), those who have non-ST-elevation acute myocardial infarction (AMI) are at higher risk for subsequent adverse events. To determine predictors of AMI in patients with UAP, we studied consecutive nonreferral patients with UAP or AMI admitted from the emergency department to the intensive care or telemetry units of an urban teaching hospital over 1 year. There were 280 study patients (mean age 66 years, 1/3 women); 24% had AMI at presentation, whereas 76% had UAP without evidence of AMI. Thresholds of > or = 3 involved leads (odds ratio [OR] 3.3; 95% confidence intervals [CI] 1.6 to 6.9) and > or = 0.2 mV (OR 5.1; 95% CI 2.2 to 11.6) of ST depression on the presenting electrocardiogram were strongly associated with AMI. The multivariate predictors of AMI were reported duration of symptoms >4 hours (OR 3.8; 95% CI 1.9 to 7.3), absence of prior revascularization (OR 3.5; 95% CI 1.6 to 7.5), absence of beta-blocker use before presentation (OR 2.8; 95% CI 1.3 to 5.8), and presence of new ST depression (OR 2.8; 95% CI 1.4 to 5.7). Using the 4 multivariate predictors, a prediction rule was developed. The percentages of patients with AMI when 0, 1, 2, 3, or 4 characteristics were present, respectively, were 7%, 6%, 24%, 46%, and 83% (p <0.001). A similar prediction rule developed from the Thrombolysis In Myocardial Ischemia III trial was validated in our cohort. Among patients with UAP, electrocardiographic and clinical variables can help immediately identify those at high risk for AMI at presentation.

Effects of prior aspirin and anti-ischemic therapy on outcome of patients with unstable angina. TIMI 7 Investigators. Thrombin Inhibition in Myocardial Ischemia

Both aspirin and beta-adrenergic blocking drugs have been shown to reduce the risk of death or acute myocardial infarction (AMI) in patients with unstable angina, but their effect during chronic use on the presentation of acute coronary syndromes is less well defined. Calcium antagonists and oral nitrates are also widely prescribed for patients with coronary disease, but their effect on presentation of acute myocardial ischemia is unknown. We retrospectively examined the effects of prior aspirin and anti-ischemic medical therapy on clinical events in 410 patients hospitalized for unstable angina. Ischemic pain occurred at rest for a duration of 5 to 60 minutes. During hospitalization, 97% of patients received aspirin and all received the direct thrombin inhibitor bivalirudin for at least 72 hours. Despite being older and more likely to have risk factors for coronary disease and poor outcome, patients receiving aspirin before admission were less likely to present with non-Q-wave AMI (5% vs 14% in patients not on aspirin, p = 0.004). Prior beta blocker, calcium antagonist, or nitrate administration did not appear to modify presentation as unstable angina or non-Q-wave AMI. In a multivariate model, the combined incidence of death, AMI not present at enrollment, or recurrent angina was best predicted by age (adjusted odds ratio [95% confidence interval] 2.38 [1.14 to 3.98]) and presence of electrocardiographic changes with pain on presentation (adjusted odds ratio 2.83 [1.50 to 5.35]) but was not related to prior or in-hospital medical therapy. Thus, aspirin but not anti-ischemic therapy before hospitalization of patients with unstable angina was associated with a decreased incidence of non-Q-wave AMI on admission.