Effects of streptokinase in patients presenting within 6 hours of prolonged chest pain with ST segment depression

Clinical implications of a next-day follow-up electrocardiogram in patients with non-ST elevation acute coronary syndromes

BACKGROUND

The prognostic value of admission ST-segment changes in patients with non-ST elevation acute coronary syndromes (NSTE ACS) is well established; however, the value of a next-day follow-up electrocardiogram (ECG) is unclear.

METHOD

We evaluated ST-depression (ST(downward arrow)) and Q-wave status on the admission and 24 to 36-hour follow-up ECG in 2,743 patients in a prospective Canadian ACS registry.

RESULTS

Of patients with ST(downward arrow) > or =1 mm on admission (n = 533 [19.4%]), 366 (68.7%) normalized their ST segment on follow-up ECG. Among patients without ST(downward arrow) on admission (n = 2,110), 97 (4.4%) developed new ST(downward arrow) at follow-up. Patients with normalized ST(downward arrow) at follow-up had higher 1-year myocardial infarction (MI) (10.1% vs 5.7%, odds ratio [OR] 1.77, 95% CI 1.12-2.81, P = .015) and death/MI rates (19.5% vs 10.2%, OR 1.69, 95% CI 1.18-2.41, P = .004), respectively, as compared to those who never had ST(downward arrow). Patients with persistent ST(downward arrow) had higher 1-year MI (10.8% vs 5.7%, OR 1.95, 95% CI 1.09-3.51, P = .025) and death/MI rates (25.6% vs 10.2%, OR 1.78, 95% CI 1.13-2.79, P = .013), respectively. In multivariable analysis, ST(downward arrow) on baseline ECG was an independent predictor of 1-year mortality; however, ST(downward arrow) on the follow-up ECG did not provide additional prognostic value. There were no differences in outcomes between the 4 different Q-wave status groups.

CONCLUSIONS

Although dynamic and persistent ST(downward arrow) are associated with worse unadjusted outcome in patients with NSTE ACS, there was no incremental prognostic value of a follow-up ECG evaluating ST depression and/or Q-wave status beyond that already provided by the initial ECG together with established prognostic factors.

Q-wave evolution of a first acute myocardial infarction without significant ST segment elevation

BACKGROUND

Some patients with acute myocardial infarction presenting without significant ST segment elevation develop a Q-wave infarction. It is unclear whether these patients can be identified from the admission electrocardiogram (ECG) and whether they differ in their in-hospital prognosis from those who retain a non-Q-wave myocardial infarction.

METHODS

In 432 consecutive patients admitted to our centre with a first acute myocardial infarction without Q waves and with ST segment amplitudes < or =0.1 mV on admission, we assessed the frequency, the electrocardiographic predictors and the short-term implications of a Q-wave evolution.

RESULTS

In 94 patients (22%), a Q-wave myocardial infarction evolved before hospital discharge (14 anterior, 26 inferior, six lateral, and 48 posterior). Minor anterior ST segment elevation was 36% sensitive and 95% specific in predicting anterior Q waves; minor inferior ST segment elevation, 42% and 89%, respectively, for inferior Q waves; and a maximal ST segment depression > or =0.2 mV in leads V2-V3 with upright T waves and without remote ST segment depression, 38% and 97%, respectively, for posterior R waves. Although patients with a Q-wave evolution had a greater creatinkinase MB peak than those retaining a non-Q-wave pattern (191+/-113 vs. 105+/-77 IU/l, respectively, P<0.001), they experienced a benign in-hospital course, with similar risk of severe complications after adjustment for the baseline clinical predictors than non-Q-wave patients.

CONCLUSIONS

About one fifth of patients with a first acute myocardial infarction without a significant ST segment elevation develop a Q-wave infarction and the admission ECG can help identify them. This evolution, however, is not associated with a worse in-hospital outcome.

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.

Does coronary artery morphology predict favorable results of intracoronary thrombolysis in patients with unstable angina pectoris?

The efficacy of intracoronary thrombolysis (ICT) for unstable angina pectoris (UAP) has been limited, despite the similar pathogenesis between UAP and acute myocardial infarction. To ascertain the subset of UAP suitable for ICT, the clinical responses to ICT were assessed in patients with UAP. Eighty-2 patients with medically refractory angina were divided into 2 groups according to the coronary artery morphology of the culprit lesion before ICT: (1) lesions with acute cut off and/or filling defects (AC) and (2) lesions with a tapered shape (TA). The TIMI flow grade was determined from coronary angiograms before and immediately after ICT. The diameter stenosis (%DS) and minimal lumen diameter (MLD) of the culprit lesion were determined using quantitative coronary angiographic analysis before and immediately after ICT. In addition, inhospital cardiac event rates including urgent/emergency coronary angioplasty or bypass surgery, nonfatal myocardial infarction or cardiac death were compared between the 2 groups. Multivariate logistic regression analysis was performed using 13 clinical factors contributing to successful ICT. The results showed that all 3 coronary angiographic parameters (TIMI flow, %DS, and MLD) significantly improved in the AC group (p<0.01, p<0.01 and p<0.05, respectively), whereas none of these parameters improved in the TA group. The inhospital cardiac event rate after ICT was significantly higher in the TA group (76%) than in the AC group (48%; p=0.016). Odds ratio predicting successful ICT was 7.09 (p<0.01) for the AC lesion, and 2.54 (p<0.01) for new angina. In conclusion the AC lesions are more commonly associated with coronary thrombosis that responds to ICT than are the TA lesions. Thus, the coronary angiographic morphology may be an important predictor for a successful ICT in patients with medically refractory UAP.

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.

A prospective randomized trial of triage angiography in acute coronary syndromes ineligible for thrombolytic therapy. Results of the medicine versus angiography in thrombolytic exclusion (MATE) trial

OBJECTIVES

The purpose of this study was to determine if early triage angiography with revascularization, if indicated, favorably affects clinical outcomes in patients with suspected acute myocardial infarction who are ineligible for thrombolysis.

BACKGROUND

The majority of patients with acute myocardial infarction and other acute coronary syndromes are considered ineligible for thrombolysis and therefore are not afforded the opportunity for early reperfusion.

METHODS

This multicenter, prospective, randomized trial evaluated in a controlled fashion the outcomes following triage angiography in acute coronary syndromes ineligible for thrombolytic therapy. Eligible patients (n=201) with <24 h of symptoms were randomized to early triage angiography and subsequent therapies based on the angiogram versus conventional medical therapy consisting of aspirin, intravenous heparin, nitroglycerin, beta-blockers, and analgesics.

RESULTS

In the triage angiography group, 109 patients underwent early angiography and 64 (58%) received revascularization, whereas in the conservative group, 54 (60%) subsequently underwent nonprotocol angiography in response to recurrent ischemia and 33 (37%) received revascularization (p=0.004). The mean time to revascularization was 27+/-32 versus 88+/-98 h (p=0.0001) and the primary endpoint of recurrent ischemic events or death occurred in 14 (13%) versus 31 (34%) of the triage angiography and conservative groups, respectively (45% risk reduction, 95% CI 27-59%, p=0.0002). There were no differences between the groups with respect to initial hospital costs or length of stay. Long-term follow-up at a median of 21 months revealed no significant differences in the endpoints of late revascularization, recurrent myocardial infarction, or all-cause mortality.

CONCLUSIONS

Early triage angiography in patients with acute coronary syndromes who are not eligible for thrombolytics reduced the composite of recurrent ischemic events or death and shortened the time to definitive revascularization during the index hospitalization. Despite more frequent early revascularization after triage angiography, we found no long-term benefit in cardiac outcomes compared with conservative medical therapy with revascularization prompted by recurrent ischemia.

"Inadvertent" thrombolytic administration in patients without myocardial infarction: clinical features and outcome

STUDY OBJECTIVES

Increasing pressure to deliver thrombolytic agents quickly to patients with suspected myocardial infarction (MI), along with expanded indications, may contribute to inappropriate administration of these agents, with potentially catastrophic results. We sought to identify the extent to which MI is ruled out in patients given thrombolytic therapy for acute MI and to characterize the clinical course and outcome in such patents.

METHODS

We studied 609 consecutive patients admitted to the CCU of an urban teaching hospital who were treated with thrombolytic agents for suspected acute MI between January 1986 and December 1993. In 35 (5.7%), MI was ruled out on the basis of persistently normal serum creatine kinase-MB isoenzyme levels. Hospital course and alternative diagnoses were established by means of chart review and database inquiry.

RESULTS

Patients in whom MI was ruled out were similar to those with MI with regard to baseline demographic and clinical features. Presenting ECGs in patients without MI were less likely to show Q waves (43 versus 64%, P < .02) but more likely to show left ventricular hypertrophy (26 versus 7%, P = .001) and nonspecific ST-segment and T-wave changes (54 versus 32%, P < .01) compared the ECGs of MI patients. Transient ST-segment elevation was detected in 51%. Hospital complications of patients without MI were similar to those of MI patients. No patient in whom MI was ruled out sustained a major hemorrhage. Final diagnoses of patients without MI included unstable angina (n = 20, 57%) undefined chest pain (n = 8, 17%) pericarditis (n = 3), pancreatitis (n = 2), esophagitis (n = 1), and aortic dissection (n = 1). Two patients died, one of aortic dissection and another of pericarditis.

CONCLUSION

In a consecutive series of CCU patients in whom MI was ruled after thrombolysis, we found no demographic or presenting clinical features to distinguish them from patients in whom MI was diagnosed. Transient ST-segment elevation potentially justifying thrombolytic therapy was present in more than half of the patients in whom MI was ruled out but may have represented transient coronary occlusion, coronary spasm, or other manifestations of unstable angina. In this study, patients in whom MI was ruled out had a high incidence of coronary disease and risk of in-hospital complications similar to that of patients with acute MI. Our findings support the rationale and safety of policies to rapidly and aggressively administer thrombolytic agents in the emergency department.