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Confirming the “gender paradox,” a large single-center registry shows that younger women with ST-segment elevation myocardial infarction (STEMI) fare worse than their male counterparts after percutaneous coronary intervention (PCI) despite having less severe disease. Older men and women, meanwhile, show no such difference according to the study published online January 31, 2013, in the European Heart Journal: Acute Cardiovascular Care.
Researchers led by Amber M. Otten, MD, of Isala Klinieken (Zwolle, the Netherlands), looked at 6,746 STEMI patients who underwent primary PCI at their institution between 1998 and 2008 and were enrolled in the Zwolle MI Study Registry.
Men (n = 4,991) and women (n = 1,755) were analyzed according to an age cut off of 65 years.
Overall mortality was higher in women than in men at 30 days (HR 2.1; 95% CI 1.6-2.5) and at 1 year (HR 1.6; 95% CI 1.3-1.9). At 30 days and 1 year, mortality also was higher in younger women compared with younger men, but in the older group, this difference was no longer evident by 1 year (table 1).
Table 1. Mortality by Gender and Age
< 65 Years30 Days1 Year
≥ 65 Years30 Days1 Year
On multivariable analysis, younger women remained at higher risk for mortality at 1 year compared with younger men (HR 1.68; 95% CI 1.108-2.569) while there was no difference in mortality risk between older women and older men (HR 1.02; 95% CI 0.762-1.370).
Younger women showed less obstructive coronary disease than younger men, with a higher TIMI 3 flow on angiography (24.6% vs. 19.9%; P = 0.008) and a lower CK release (1,400 vs. 1,691; P = 0.001). In the older age group, the incidence of multivessel disease and TIMI 3 flow before PCI were similar between men and women.
The study authors note that there were no differences in therapeutic approaches between men and women since treatment strategies in the acute setting are standardized at their institution. “It is alarming, however, that, although younger women had a lower risk profile at baseline, with more TIMI 3 flow before PCI and less multivessel disease, they had a higher mortality than similarly aged men,” Dr. Otten and colleagues write.
Less Re-PCI, More Smoking Cited as Factors
They note several potential explanations for their findings. First, younger women were less likely to undergo re-PCI than younger men at 30 days (4.3% vs. 6.7%; P = 0.02), the time period during which almost half of all re-PCI procedures were performed and when most gender-related mortality differences were apparent.
Also, in the younger age group, more women were current smokers than men (67% vs. 60%; P < 0.001). Some studies have suggested that smoking increases the risk of acute MI more so in women compared with men, the authors note. Oral contraceptives also may enhance the risk of arterial thrombosis and MI in younger women, although data on the percentage of women in the study using contraceptives is lacking.
In addition, they add, “Gender-related differences in pathophysiology of STEMI in women at younger age may also increase mortality.” In particular, non-obstructive CAD with microvascular dysfunction and abnormal coronary reactivity may be of relatively increased importance in women with STEMI and affect their prognosis negatively.
“Our current findings confirm the existence of the so called ‘gender paradox’ in young women with STEMI,” the authors conclude.
Hypertension was more prevalent in both younger and older women compared with men.
In younger women, a positive family history and current smoking were more prevalent, while older-age women had more diabetes. In both age groups, total ischemic time and patient delay before hospital admission were longer in women, whereas there was no gender difference in in-hospital delay from admission to first balloon inflation.