ACC: Is treatment equality protocol needed to reduce post-MI mortality in women?

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ATLANTA--Women might be more likely to survive a heart attack if they were treated more like men, with increased use of PCI and other invasive techniques, according to a trial presented today during the late-breaking clinical trials session at the American College of Cardiology’s (ACC) 59th annual conference.

Primary investigator Francois Schiele, MD, professor of cardiology and cardiology chief at the University Hospital of Besancon in France, reviewed several previous studies (i.e., N Engl J Med 1998;338:8-14/N Engl J Med 1999;341:217-25/JAMA 2009;302:874-82) that have suggested women fare worse than men after acute MI, with a higher risk of death after a heart attack than men. He noted the “reasons have been unclear.”

“The main question we tried to answer with this study was whether the difference in mortality between women and men after a heart attack is explained by differences in management,” Schiele said.

Previous studies have found that women admitted for acute MI have 40-100 percent higher mortality at 30 days, as compared with men. Yet, this over-mortality is reduced after adjustment for age and co-morbidities, according to Schiele. However, the sex-age interaction indicates a discrepancy between studies and the STEMI and non-STEMI patients also are not equivalent.

As a result, Schiele and colleagues sought to assess the effects of clinical characteristics and treatments on gender difference, using a propensity score-matched analysis.

In a multicenter study of more than 3,000 patients admitted to the hospital for a heart attack, women were far less likely than men to go to the cardiac cath lab for angiography or angioplasty, and about twice as likely to die within a month of having the heart attack.

For the study, researchers analyzed data from a regional registry that included all patients treated for a heart attack between January 2006 and December 2007. Of the 3,510 patients in the study, 1,119 (32 percent) were women. A data comparison showed that women were, on average, nine years older than men, had more health problems, received fewer effective treatments for heart attack, and were nearly twice as likely to die, both during the initial hospital stay (9.7 vs. 5 percent) and over the following month (12.4 vs. 7 percent).

Researchers used a statistical method known as propensity score matching, which attempts to reduce the bias of treatment-effect estimates from observational studies, to create pairs of men and women closely matched according to baseline characteristics (by up to eight digits of their propensity scores). This created a population of 1,298 patients composed of 649 pairs. A second population of matched pairs was created by taking into account not only baseline characteristics but also the treatments and strategies actually used for each patient. This population of 584 pairs represented 1,168 patients.

Schiele explained that “because the procedure is very precise, not all patients could be matched.”

When the investigators analyzed data from the first 649 pairs, they found that despite very similar clinical characteristics, men were 57 percent more likely than women to undergo coronary angiography. Among STEMI patients, men were far more likely than women to receive therapy to reopen the blocked artery, whether by clot-busting drugs (used 72 percent more often in men) or by PCI (used 24 percent more often in men).

Schiele attributes the lack of heterogeneity of treatment with angiography on a bias of the technology, and noted that a specific gender-based protocol would be needed to change this slant.

The death rate during the initial hospital stay was 48 percent lower in men than in women, and the death rate within 30 days of the heart attack was about 30 percent lower in men, although this last finding was of borderline statistical significance, Schiele reported.

Finally, the researchers found that when a special statistical method was used to closely match patients by both baseline clinical characteristics and treatments, death rates were similar among men and women.

“This suggests that we could reduce mortality in female patients by using more invasive procedures,” said Schiele. “When there are no clear contraindications, women should be treated with all recommended strategies, including invasive strategies.”

“We need to improve outcomes in women who have a heart attack,” Schiele said. “There is a difference in outcomes between women and men, and we need to know what it stems from and what we can do about it.”

In her response as discussant, Rita F. Redberg, MD, from the University of California, San Francisco Medical Center, commented that this study confirms the findings that women are dying sooner from an MI and the female population is commonly older when they present to the hospital with a heart attack.

She pointed out that the trial also revealed that “younger women in particular have greater differences in mortality than men. However, those were corrected with statistical corrections.” This lead Redberg to question whether younger women (between 50-60 years) have a more virulent coronary disease, like younger breast cancer patients.