In-Hospital Mortality Equal for Men, Women After PCI for STEMI

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Yet another study on how women fare after ST-segment elevation myocardial infarction (STEMI) shows that, even in the contemporary era of primary percutaneous coronary intervention (PCI), female patients face higher in-hospital death rates than their male counterparts. But the paper, published in the January 2011 issue of the American Heart Journal, suggests that the mortality difference between men and women can largely be explained by the fact that women are treated at older ages and have more comorbidities. In contrast, transfusion and vascular complications remain an issue.

Researchers led by Hitinder S. Gurm, MD, of the University of Michigan Health System (Ann Arbor, MI), looked at 8,771 STEMI patients enrolled in the Blue Cross Blue Shield of Michigan Cardiovascular Consortium (BMC2) registry who underwent primary PCI from 2003 to 2008. Among them, 2,542 (29%) were women.

Patients, Treatment Diverge

The study documented an array of differences between male and female registry patients. At baseline, women tended to be older and were less likely to be white or current smokers. Comorbidities such as hypertension, diabetes, congestive heart failure, noncardiac vascular disease, and chronic obstructive pulmonary disease were more prevalent in women, as was cardiogenic shock. On the other hand, prior PCI and MI were less common in women than in men.

In terms of procedural differences:

  • Door-to-balloon time was lower for male patients
  • Women received smaller absolute amounts of contrast media during catheterization but were more likely than men to exceed the maximum allowable dose
  • Vascular closure devices and glycoprotein IIb/IIIa inhibitors were more often given to men than to women

Furthermore, disease characteristics varied. Men were more likely to have thrombus, while women more frequently had calcified arteries. However, there were no gender differences with regard to prevalence of multivessel or left main disease.

After PCI, women were less likely than men to receive statins, ACE inhibitors, and calcium-channel blockers, or to be referred for cardiac rehabilitation. Aspirin, warfarin, clopidogrel, and beta-blocker use all were similar regardless of patient sex.

Bleeding Weighs Heavier Than Mortality

Several in-hospital outcomes were worse for women compared with men, including gastrointestinal bleeding, nephropathy, post-procedure transfusion, stroke, vascular complications, and death. But a propensity-matched analysis that controlled for age and comorbidities helped narrow that list down, such that only transfusion and vascular complication risk remained higher for female patients. Importantly, the mortality difference was no longer significant (table 1).

Table 1. Odds Ratio (95% CI): Women vs. Men

 

All Data
(n = 8,771)

Matched Data
(n = 4,262)

Gastrointestinal Bleeding

1.74 (1.36-2.21)

1.19 (0.87-1.63)

Contrast Nephropathy

1.75 (1.46-2.11)

1.09 (0.87-1.37)

Postprocedure Transfusion

2.84 (2.48-3.24)

1.88 (1.57-2.24)

Stroke

1.85 (1.15-2.97)

1.37 (0.76-2.49)

Death

1.79 (1.45-2.22)

1.30 (0.98-1.72)

Vascular Complication

2.13 (1.75-2.59)

1.65 (1.26-2.14)


Over time, yearly rates of in-hospital death among women appeared to decrease. For example, the rate was 7.56% in 2003 compared with 5.26% in 2008 (P for trend = 0.17).

Matching Matters

Speaking with TCTMD in a telephone interview, Dr. Gurm said the study offers a unique perspective. “A lot of the analysis that has been done in the past looking at women and outcomes has been somewhat, I wouldn’t say flawed, but it has not been robust enough. Because when women present with heart disease they are usually almost 7 to 10 years older than men, and they have other comorbidities,” he explained. “So to compare a 78-year-old female who comes in with a STEMI with a 55-year-old male with a STEMI—and then say they have worse outcomes—is not the best way to do it.”

Rather than do a more traditional logistic regression analysis, the researchers chose instead to perform propensity matching. “To me, that is more of an ‘apples to apples’ comparison,” he said.

That choice seems to have made a difference, Dr. Gurm explained. The unadjusted data are similar to what previous studies have reported, namely that women have an in-hospital mortality risk nearly double that of men.

“But once you adjust for those baseline differences, the only thing that stands out, which to me is very interesting, is that women have a higher rate of bleeding and vascular complications,” he said. “If you ask any interventionalist who’s been doing this for a while, they’ll always tell you that the patients who bleed are always elderly women, out of proportion to what you would see in any other subgroup.”

The explanation for these disparities is not clear, he noted. “There is some concern that because of the different exposure to estrogen and testosterone, women’s arteries are different,” Dr. Gurm said. “I could understand that in perimenopausal or premenopausal women, but we’re looking mostly at elderly women. So I don’t really know the answer to that.”

Noting another possibility, Dr. Gurm pointed out that women in the current study tended to have poorer overall renal function than men; female subjects were more likely to have a glomerular filtration rate (GFR) below 30 mL/m2. This difference might affect their response to antiplatelet therapy and lead to increased bleeding risk. However, the researchers did not try to adjust for this variable during propensity matching, he said.

Dr. Gurm added that the choice of antiplatelet therapy also may matter. “When the study was done, over 80% of the time people were getting glycoprotein IIb/IIIa inhibitors, and it definitely caused more bleeding. We now have data suggesting that there are alternatives. Bivalirudin seems to be getting very good results,” he said. “Another option to consider would be radial intervention. That definitely reduces complications.”

Dr. Gurm reported that he and his colleagues intend to investigate whether patients with abnormal renal function who undergo PCI face increased risk of bleeding, and whether women with low GFR should be managed differently. And while radial access is still rarely used in treating STEMI patients within the United States, he expressed interest in seeing how the uptake of that approach affects outcomes.

 


Source:
Jackson EA, Moscucci M, Smith DE, et al. The association of gender with outcomes among patients undergoing primary percutaneous coronary intervention for ST elevation myocardial infarction in the contemporary era: Insights from the Blue Cross Blue Shield of Michigan Cardiovascular Consortium (BMC2). Am Heart J. 2011;161:106-112.e1.

 

 

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Disclosures
  • The BMC2 registry is supported by the Blue Cross Blue Shield of Michigan.
  • Dr. Gurm reports no relevant conflicts of interest.

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