Current issues of ACP Journal Club are published in Annals of Internal Medicine


Prognosis

Early ischemia after thrombolytic therapy for a first myocardial infarction was associated with increased total cardiac events and emergency revascularization

ACP J Club. 1993 Nov-Dec;119:82. doi:10.7326/ACPJC-1993-119-3-082


Source Citation

Silva P, Galli M, Campolo L, for the IRES (Ischemia Residua) Study Group. Prognostic significance of early ischemia after acute myocardial infarction in low-risk patients. Am J Cardiol. 1993 May 15;71:1142-7.


Abstract

Objective

To study the prognostic relevance of early ischemia after thrombolytic therapy for first acute myocardial infarction (MI).

Design

Inception cohort from the Italian multicenter Ischemia Residua study (part of GISSI-2) followed for 6 months.

Setting

22 coronary care units (CCUs) in Europe.

Patients

453 patients (mean age 55 y, 396 men) who had chest pain with ST-segment elevation had been admitted to a CCU within 6 hours of symptom onset, had no contraindications to fibrinolytic therapy or heparin, were ≥ 70 years of age, had an uncomplicated course in the first 24 hours, and had not had a previous MI. 6-month follow-up was 95%.

Assessment of prognostic factors

Early ischemia was defined as transient, spontaneous ST-segment depression or elevation > 1 mm from baseline or T-wave inversion in any electrocardiographic (ECG) lead, or both, that occurred ≥ 24 hours after symptom onset and before discharge from the CCU. Only single-lead continuous and 12-lead ECG recordings were used. Location of ischemia with respect to the infarct site and severity were recorded. Chest pain without ECG changes was not included.

Main outcome measures

Mortality, nonfatal MI defined by ECG and laboratory values, urgent coronary revascularization, and recurrent angina during hospitalization and for 6 months after discharge.

Main results

35 patients (8%) had 45 episodes of early ischemia in the CCU. Patients who had early ischemia during hospitalization, compared with patients who did not have early ischemia, had more reinfarction (28% vs 2%, odds ratio [OR] 18, 95% Cl 6 to 54), more emergency revascularization (14% vs 1 %, OR 23, Cl 5 to 75), and more cardiac events overall (43% vs 5%, OR 15, Cl 7 to 45). The groups did not differ for mortality or elective revascularization. After 6 months the groups did not differ for mortality, reinfarction, recurrent angina, total events, or elective revascularization. Kaplan-Meier life-table survival curves showed a decrease in survival without reinfarction and survival without combined cardiac events in patients with early ischemia compared with patients without early ischemia.

Conclusion

Patients with early ischemia after thrombolytic therapy for a first acute myocardial infarction had increased in-hospital total cardiac events, reinfarction, and emergency revascularization compared with patients without early ischemia.

Source of funding: Not stated.

For article reprint: Dr. P. Silva, Division of Cardiology, Fondazione Clinica del Lavoro, Via Revislate 13, Veruno 28010 (NO), Italy. FAX 39-322-830-294.


Commentary

Silva and colleagues used standard postinfarction monitoring methods (single-lead rhythm monitoring and 12-lead ECG) to detect recurrent ischemia and predict outcome in patients with ST-segment elevation after acute MI treated with thrombolytic therapy. Patients with recurrent ischemia had a higher risk for in-hospital events (nonfatal MI and emergency revascularization). Interestingly, after hospital discharge these findings did not predict a worsened outcome. The study did not indicate how often ischemia was detected in the absence of symptoms.

This study shows that easily detectable ischemic episodes > 24 hours after thrombolytic therapy are associated with a high rate of in-hospital events. Clinicians should remain highly vigilant for these episodes, and their detection should prompt intensification of therapy. The study does not address whether percutaneous intervention, bypass surgery, or intensified medical therapy would be the most effective way to improve prognosis. Current practice is to ensure that the patient receives adequate antithrombotic therapy (aspirin and heparin with maintenance of a therapeutic prothrombin time), β-blockers (unless contraindicated), and nitrates. Although the benefit remains unproven, most experts also recommend early coronary angiography in these patients.

This study should not be confused with studies of silent myocardial ischemia that have used ambulatory monitoring to detect episodes of ST-segment deviation in the absence of symptoms. These studies have had mixed results indicating an effect on prognosis; some indicate a minimal effect compared with the prognostic importance of symptomatic myocardial ischemia.

The authors' recommendation that in the absence of spontaneous ischemia no further early risk stratification is required seems unfounded given the study's small sample size and brief follow-up period. Patients in this relatively young cohort with adverse outcomes may have worse long-term outcomes measurable only during a period of many years.

Robert M. Califf, MD
Duke University Medical CenterDurham, North Carolina, USA


Editorial Comment:

More recent studies show a higher risk for death and reinfarction in patients with angina pectoris early after acute MI even when stabilized in hospital with medical therapy (1), and improved outcomes in patients after MI who also have inducible ischemia when treated aggressively with early angiography and revascularization compared with conservative initial medical treatment (2). When high risk patient groups, such as those with hemodynamic or electrical instability early after acute MI and those with significant left venticular dysfunction, may also benefit from early coronary angiography and revascularization.

Patients without angina after MI and without significant left ventricular dysfunction are at low risk for recurrent events and should be further risk stratified by results of provocative testing for ischemia. In the absence of significant ischemia with provocative tests, conservative management appears safe (3).


References

1. The GISSI-3 APPI Study Group. Early and six-month outcome in patients with angina pectoris early after acute myocardial infarction (The GISSI-3 APPI [Angina Precoce Post-Infarcto] Study) . Am J Cardiol. 1996;78:1191-7.

2. Madsen JK, Grande P, Saunamäki K, et al., on behalf of the DANAMI Study Group. Danish multicenter randomized study of invasive versus conservative treatment in patients with inducible ischemia after thrombolysis in acute myocardial infarction (DANAMI). Circulation. 1997;96:748-55.

3. Peterson ED, Shaw LJ, Califf RM. Risk stratification after myocardial infarction. Ann Intern Med. 1997;126:561-82.