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Prognosis

Women had a worse prognosis than men after myocardial infarction

ACP J Club. 1999 Mar-April;130:46. doi:10.7326/ACPJC-1999-130-2-046


Source Citation

Marrugat J, Sala J, Masiá R, et al. Mortality differences between men and women following first myocardial infarction. JAMA. 1998 Oct 28;280: 1405-9.


Abstract

Question

What are the sex differences in mortality and hospital readmission after a first acute myocardial infarction (MI)?

Design

Inception cohort study (Resources Used in Acute Coronary Syndrome and Delays in Treatment Study) with 6-month follow-up.

Setting

Outpatient clinics of 4 teaching hospitals in Catalonia, Spain.

Patients

1460 consecutive patients (77% men) ≤ 80 years of age with a first acute MI who were hospitalized within 72 hours of onset of acute MI symptoms. Diagnosis was confirmed by electrocardiographic findings, cardiac enzyme levels, and chest pain. Patients living outside the study area or who had other life-threatening diseases, previous coronary artery bypass grafting, percutaneous transluminal coronary angioplasty, or coronary angiography in the past 6 months were excluded. Follow-up was 99.8%.

Assessment of prognostic factors

Demographic characteristics, smoking status, medical history, clinical condition, and length of hospital stay.

Main outcome measures

Mortality and hospital readmission (for reinfarction, ventricular fibrillation or tachycardia, congestive heart failure, or unstable angina) at 28 days and 6 months.

Main results

Compared with men, women were older (mean age 68.6 vs 60.1 y, P < 0.001) and more likely to have diabetes (52.9% vs 23.3%, P < 0.001), hypertension (63.9% vs 42.3%, P < 0.001), previous angina (44.6% vs 37.4%, P = 0.02), and acute pulmonary edema or cardiogenic shock (24.8% vs 10.5%, P < 0.001). Men were more likely to have developed severe ventricular arrhythmias (23.7% vs 14.7%, P < 0.001), been smokers (58.5% vs 11.5%, P < 0.001), had chronic obstructive pulmonary disease (21.5% vs 7.9%, P < 0.001 ), and received thrombolytic therapy (41.3% vs 23.9%, P < 0.001). Women had higher unadjusted rates of 28-day mortality (18.5% vs 8.3%, P < 0.001), 6-month mortality (28.5% vs 10.8%, P < 0.001), and 6-month readmission (23.3% vs 12.2%, P < 0.001). After adjustment for age, diabetes, hypertension, smoking status, previous angina, thrombolysis, cardiogenic shock or acute pulmonary edema, and severe arrhythmias, women had a higher rate of the combined end point of mortality or readmission at 6 months (odds ratio [OR] 1.61, CI 1.13 to 2.29) but showed no significant difference for 28-day mortality (OR 1.31, 95% CI 0.77 to 2.25) or 6-month mortality (OR 1.46, CI 0.93 to 2.29).

Conclusion

Compared with men, women had more severe first acute myocardial infarctions, were less likely to receive thrombolysis, and were at greater risk for the combined end point of death and hospital readmission at 6 months after adjustment for age, comorbid conditions, previous angina, smoking status, and use of thrombolytic therapy.

Sources of funding: Fondo de Investigación Sanitaria and Generalitat de Catalunya.

For correspondence: Dr. J. Marrugat, Unitat de Lipids i Epidemiologia Cardiovascular, Institut Municipal d'Investigaciö Médica, Dr Aiguader 80, E-08003 Barcelona, Spain. FAX 34-93-221-3237.


Commentary

The study by Marrugat and colleagues adds to previous evidence that the intermediate prognosis after MI is worse in women than in men (1). Consistent with other studies, women were on average older and more likely to have unfavorable baseline characteristics. Time from symptom onset to hospital presentation was delayed among women (3.3 vs 2.3 h, P < 0.001), and this may account for the observation that fewer women received thrombolysis.

Although the unadjusted 28-day and 6-month mortality and readmission rates were higher in women, some (but not all) of the excess mortality was explained by sex differences in age, baseline variables, and thrombolytic use. The conclusions are similar to those from previous studies and reviews (1-3) and suggest that even after adjustment for known prognostic variables, a small independent association exists between being a woman and mortality in acute MI.

In contrast to many similar studies, Marrugat and colleagues followed a consecutive group of patients without previous MI and who were not participants in a clinical trial. In addition to selection bias, patients in treatment trials may undergo angio-graphic investigation and revascularization procedures that can influence prognosis (2). Another strength of the cohort is the more modest and similar 6-month procedural rate between men and women, which makes it less likely that this factor influenced the observed sex-related differences in outcome.

It is difficult to adjust for the effect on outcome of delays in hospitalization and the resultant delay of important therapies. The effectiveness of thrombolysis depends greatly on the time between onset of chest pain and delivery of therapy, but the effects of delaying aspirin or β-blocker therapy is less clear. In any event, this study showed that women came to the hospital later than men. We need to recognize and address the importance of earlier presentation, diagnosis, and treatment of women with acute MI.

Shaun Goodman, MD, MSc
St. Michael's HospitalToronto, Ontario, Canada


References

1. Vaccarino V, Krumholz HM, Berkman LF, Horwitz RI. Sex differences in mortality after myocardial infarction. Is there evidence for an increased risk for women? Circulation. 1995;91:1861-71.

2. Weaver WD, White HD, Wilcox RG, et al. Comparisons of characteristics and outcomes among women and men with acute myocardial infarction treated with thrombolytic therapy. GUSTO-I investigators. JAMA. 1996;275:777-82.

3. Malacrida R, Genoni M, Maggioni AP, et al. A comparison of the early outcome of acute myocardial infarction in women and men. The Third International Study of Infarct Survival Collaborative Group. N Engl J Med. 1998;338:8-14.