Myocardial Infarction Symptom Presentation

Abstract & Commentary

By Andrew J. Boyle, MBBS, PhD, Assistant Professor of Medicine, Interventional Cardiology, University of California, San Francisco. Dr. Boyle reports no financial relationships relevant to this field of study.

This article originally appeared in the April 2012 issue of Clinical Cardiology Alert. It was edited by Michael H. Crawford, MD, and peer reviewed by Ethan Weiss, MD. Dr. Crawford is Professor of Medicine, Chief of Clinical Cardiology, University of California, San Francisco, and Dr. Weiss is Assistant Professor of Medicine, Division of Cardiology and CVRI, University of California, San Francisco. Dr. Crawford reports no financial relationships relevant to this field of study, and Dr. Weiss is a scientific advisory board member for Bionovo.

Source: Canto JG, et al. Association of age and sex with myocardial infarction symptom presentation and in-hospital mortality. JAMA 2012;307:813-822.

Timely recognition and treatment of myocardial infarction (MI) are crucial if we are to achieve optimal outcomes for our patients. Silent ischemia, or the absence of classical symptoms of ischemia, may delay the diagnosis. In patients presenting with MI, delay in diagnosis and treatment may have disastrous outcomes. Accordingly, Canto and colleagues analyzed data from the National Registry of MI (NRMI) to assess the frequency with which men and women were admitted for MI without chest pain and the effect that presenting without chest pain has on mortality.

The investigators studied more than 1.1 million patients (42% women) presenting with MI, both ST elevation MI (STEMI) and non-ST elevation MI (non-STEMI) from 1994-2006. The in-hospital mortality rate was 14.6% for women and 10.3% for men (P < 0.001). The proportion of MI patients who presented without chest pain was an alarming 35%. Women presenting with MI were more likely than men to present without chest pain (42% vs. 31%; P < 0.001). In addition, advancing age was associated with higher rates of MI without chest pain, but interestingly the gender differences actually became less pronounced with age. Patients presenting without chest pain were more likely to have diabetes, to have delayed presentation, to present with non-STEMI, and to present in Killip class III or IV, whereas those with chest pain were more likely to present with anterior MI and STEMI. Patients without chest pain were less likely to receive aspirin, beta-blockers, antithrombins, antiplatelet agents, or reperfusion therapy. Furthermore, when they did receive the appropriate treatments, those who presented without chest pain experienced significant delays.

After statistical adjustment for clinical characteristics, comorbidities, treatments received, and delays, younger men and women who suffer MI without chest pain were more than twice as likely to die from their MI than those who had chest pain. However, with advancing age this difference was attenuated, and at age ≥ 75 years men were 32% more likely to die and women were 8% more likely to die than their counterparts with chest pain. The authors conclude that in patients hospitalized with MI, women were more likely than men to present without chest pain and had higher mortality than men within the same age group, but sex differences in clinical presentation without chest pain and in mortality were attenuated with increasing age.

Commentary

I am struck by the significant rate of MI without chest pain (35%) in this study. Although this was higher in women (42% vs. 31%), the rate of MI without chest pain is still alarmingly high in both sexes and we should have a high index of suspicion for acute MI in patients with atypical presentations. One may intuitively think that non-STEMI were more likely to present without chest pain than STEMI. This is true in the current study, but interestingly more than one-third of all STEMI also presented without chest pain. Delays in treatment were seen in patients without chest pain, and this could lead to serious outcomes in MI patients. This was demonstrated by the higher mortality in those without chest pain in this study. Interestingly, the difference between genders became less apparent with age, but the total proportion of patients presenting with MI without chest pain increased. The reasons for this remain unknown.

The major limitation of this study is that it is a retrospective analysis of registry data. The participating hospitals may not have collected data equally, and the hospitals participating in the NRMI registry may not serve populations that are truly representative of all regions throughout the United States. However, this is an incredibly large study — involving more than a million patients — which strengthens the conclusions made. We should continue to be vigilant for atypical presentations of MI, particularly in women and older patients. Hopefully, increased awareness of painless MI presentation may hasten diagnosis and avoid treatment delays for our patients.