Emergency physicians need to rethink how they diagnose myocardial infarction, according to a new study that found atypical symptoms in MI patients, especially young women who often present without chest pain.
Changing the picture will require a change in procedures in the emergency department, said John G. Canto, MD, MSPH, the director of the Center for Cardiovascular Prevention, Research & Education at the Watson Clinic in Lakeland, FL, and the first author of the report. “In my opinion, one of the keys is to make the diagnosis of myocardial infarction promptly using broad criteria during triage,” he said, advising 12-lead electrocardiogram and cardiac biomarkers for patients with typical and atypical symptoms alike, especially among patients at risk for acute coronary syndrome.
Researchers from the National Registry of Myocardial Infarction examined predictors of patients with myocardial infarction arriving at the emergency department without chest pain and the relationship between age, sex, and mortality. The observational study included 1,143,513 patients (481,581 women and 661,932 men) between 1994 and 2006. (JAMA 2012;307:813.) Dr. Canto said a limited number of studies have considered age when examining sex differences in heart attack clinical presentation, and investigators must ask whether true gender differences exist in heart attack presentation, or if women are just older at time of heart attack and age is the important factor.
“Our results are provocative and challenge conventional wisdom,” he said. “If our results are confirmed by other investigators from other studies and databases, perhaps we need to tailor the current one-size-fits-all heart attack symptom message to include the fact that younger women [those under 55] with heart attack are at significant risk for atypical presentation and subsequent higher risk of death.”
Amal Mattu, MD, a professor and the vice chair of emergency medicine at the University of Maryland School of Medicine, praised the study for dispelling myths about the association of age and sex to the symptoms men and women exhibit when they show up in the ED and how likely they are to survive in the hospital.
Women were significantly more likely to arrive at the hospital without chest pain than men, but the difference between sexes diminished with age, the study found, with an in-hospital mortality rate of 14.6 percent for women and 10.3 percent for men. Younger women who arrived at the hospital without chest pain had higher in-hospital mortality rates than men, but the trend reversed with increasing age in an adjusted model. The interaction of sex, age, and chest pain had a significant effect on mortality, suggesting that absence of chest pain in younger women with myocardial infarction is an important predictor of mortality. “Our data also suggest that the absence of chest pain is associated with increased mortality, especially among younger women with MI, and may explain in part the excess mortality risk in this high-risk group,” the authors wrote.
The dogma had been that only older women present with atypical symptoms while younger women have more typical symptoms, Dr. Mattu said. The other myth the study dispelled was that painless myocardial infarctions are associated with a better prognosis than painful ones, he said. That proved untrue. “Younger women [in this study] present without pain more often than we would have thought,” Dr. Mattu said. “Those atypical and painless presentations may not have as bad an MI, but they have a higher mortality, even when they are properly diagnosed and admitted to the hospital.”
Dr. Mattu said he was shocked by the high mortality rate of young women in the hospital. “It's shocking to think that any disease would produce nearly 15 percent in-hospital mortality. That is high mortality.”
Dr. Canto said the death rates were greatest in younger women as compared with younger men with heart attack, and that those differences were markedly decreased and eliminated with increasing age. “The reason for higher mortality in younger women with heart attacks is largely unknown, but it is speculated that differences may be due to biological factors and the fact that younger women had a greater risk for atypical presentation than similarly aged men,” he noted. “This, in turn, may lead to patient delay in presenting to the medical establishment and lower receipt of live-saving medical treatments and invasive procedures,” which contributed a moderate effect on higher mortality.
The researchers do not know definitively why the differences between men and women attenuate with age, but Dr. Canto said they speculate that differences may be the biological differences between young women with heart attacks, such as hormonal factors, mechanisms of clot formation (plaque erosion versus rupture), hypercoagulable state, inflammation, and coronary spasm, as well as age because women are older when they have their heart attacks.
Dr. Mattu said he hopes the study explodes myths that often impede prompt treatment. “People might have a lower threshold to getting EKGs, and doctors are more in tune with the fact that you can't rely on pain in younger women as a symptom,” he said. “Textbooks are largely written based on studies of middle-aged and elderly men. The classic description is of someone clutching his chest and arm, sweating, and describing an elephant on his chest. Maybe we need to redo the studies just looking at presentation in women. What words do women use when they describe their pain?”
Women may present, he said, with nothing more than isolated nausea and vomiting, and women may not seek help because the symptoms are not typical of MI, and end up with a bad outcome.
“I'd like to point out that in both sexes, the majority of heart attack patients presented with chest pain (64%). Among women, though, chest pain was actually more common in women younger than 45 years (81%) than in women in any other age group. However, in examining gender differences in atypical presentation, younger women have a greater likelihood of atypical presentation than similarly aged men,” Dr. Canto said.
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