Different MI presentations between the sexes diminish with age, observational study finds

Women who have a myocardial infarction (MI) are more likely than men to present without chest pain and have higher mortality than men of the same age, but the differences faded with age, researchers found in an observational study.

To examine the relationship among sex, symptoms and hospital mortality, researchers conducted an observational study from the National Registry of Myocardial Infarction, an industry-funded registry of more than 1.1 million patients. In the study, 42% of patients were women, and they were significantly older than men at hospital presentation, with a mean age of 73.9 versus 66.5 years (P<0.001).

Researchers recorded the presence of chest pain (defined as any symptom of chest discomfort, sensation or pressure, or tightness) or arm, neck, or jaw pain occurring before coming to the hospital and receiving a diagnosis of MI. Results appeared in the Feb. 22/29 Journal of the American Medical Association.

The percentage of MI patients who presented without chest pain was 35.4% (95% CI, 35.4% to 35.5%) and was significantly higher among women than men (42.0% [95% CI, 41.8% to 42.1%] vs. 30.7% [95% CI, 30.6% to 30.8%]; P<0.001).

Multivariable analyses showed that sex-specific differences in MI presentation without chest discomfort decreased with advancing age. Odds ratios were broken down by age brackets comparing women to men (P<0.001 for trend):

• younger than age 45 years, 1.30 (95% CI, 1.23 to 1.36);
• age 45 to 54 years, 1.26 (95% CI, 1.22 to 1.30);
• age 55 to 64 years, 1.24 (95% CI, 1.21 to 1.27);
• age 65 to 74 years, 1.13 (95% CI, 1.11 to 1.15); and
• age 75 years or older, 1.03 (95% CI, 1.02 to 1.04).

In-hospital mortality was 14.6% for women and 10.3% for men. Younger women presenting without chest pain had higher hospital mortality than younger men without chest pain. Again, these sex differences decreased (or even reversed) as patients aged. Odds ratios for mortality comparing women to men were:

• age younger than 45 years, 1.18 (95% CI, 1.00 to 1.39);
• age 45 to 54 years, 1.13 (95% CI, 1.02 to 1.26);
• age 55 to 64 years, 1.02 (95% CI, 0.96 to 1.09);
• age 65 to 74 years, 0.91 (95% CI, 0.88 to 0.95); and
• age 75 years or older, 0.81 (95% CI, 0.79 to 0.83).

The three-way interaction (sex, age, and chest pain) on mortality was significant (P<0.001).

Absence of chest pain may be a more important predictor of death in younger women with MI compared with other similarly aged groups, the authors concluded. “Younger women who experience MI may have significantly less narrowing of the coronary arteries than older women or men, possibly because of a hypercoagulable state, inflammation, coronary spasm, or plaque erosion vs. rupture,” they wrote. Another possible explanation is sex differences in cardiovascular risk factors, they added.