HealthDay News — Women who experience myocardial infarction (MI) are more likely than men of the same age to present without chest pain and have higher in-hospital mortality, study findings indicate.

“Our data challenge the conventional wisdom that heart attack symptom messages should be the same for women and men,” John G. Canto, MD, MSPH, from the Watson Clinic and Lakeland Regional Medical Center in Florida and colleagues reported in Journal of the American Medical Association.

Researchers have already known that women who have MIs are an average of 10 to 15 years older than men, but whether or not age, rather than gender explains differences in symptom presentation among the two groups remains unclear. To explore the association between gender, symptom presentation and hospital mortality, Canto and colleagues conducted an observational study involving more than one million patients from the National Registry of Myocardial Infarction, 481,581 of whom were women, from 1994 to 2006.

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They found that women were more likely to have an atypical presentation — that is, without chest pain — than men, 42% vs. 30.7% (P < .001), and that these differences were most pronounced in younger age groups. In fact atypical presentation markedly declined with increasing age, becoming almost nonexistent in the oldest age groups. Age-specific multivariable adjusted odds ratios for atypical MI presentation were as follows:

  • Younger than 45 years, OR= 1.30
  • 45 to 54 years, OR = 1.26
  • 65 to 74 years, OR=1.13
  • 75 years or older, OR=1.03

Women also had higher in-hospital mortality rates than men, 14.6% vs. 10.3%, with the differences most pronounced among young patients without chest pain, and again attenuating and disappearing with age. Adjusted in-hospital mortality ORs for patients younger than 45 years was 1.18 compared with 1.13 among those aged 45 to 54 years; 1.02 among those aged 55 to 64 years; 0.91 among patients aged 65 to 74 years; and 0.81 for those aged 47 years and older.

“Health-care providers who care for patients who present with MI must not only take care of those with classic symptoms, but must also promptly treat patients with atypical symptoms, who are at risk for delayed receipt of lifesaving treatments,” the researchers wrote.

They cautioned that the findings may not be representative of all MI patients and called for more prospective studies to confirm the results. Several researchers disclosed financial ties to pharmaceutical and medical device companies. The National Registry of Myocardial Infarction was funded by Genentech.

Canto JG et al. JAMA. 2012; doi:10.1001/jama.2012.199.