Studies indicate why females do not fare as well as men in undergoing angioplasty for heart attacks

May 6 2009

Age, condition and treatment delay are among the reasons women who undergo angioplasty for heart attack often do not fare as well as do men, according to two studies presented today at the Society for Cardiovascular Angiography and Interventions (SCAI) 32nd Annual Scientific Sessions.

These studies, which are among the first to document outcomes in female patients treated with angioplasty and stenting for a heart attack, may help close the outcome gap between women and men.

The studies found, when compared with their male counterparts, women undergoing angioplasty for heart attack are often older (by an average of nine years), in poorer condition (such as suffering from diabetes) and have a longer onset due to delayed recognition of symptoms by both patients and their caregivers. In addition, women are less likely to develop brisk blood flow through the treated artery after percutaneous coronary intervention (PCI). As a result, women face twice the likelihood of procedural failure and an increased risk of death, according to the studies.

The studies show many people do not understand that female heart attack patients often present differently than men. Although women, like men, can experience chest pain or discomfort during a heart attack, women are somewhat more likely to have other symptoms instead, such as shortness of breath, nausea/vomiting and back or jaw pain.

"Women who have chest pain due to a heart attack often attribute it to other reasons and, therefore, come to the hospital later than men," said Itsik Ben-Dor, M.D., an interventional cardiology fellow at Washington Hospital Center in Rockville, MD. "The procedure is harder and the success rate is lower in women partly because the time is longer from the onset of symptoms to treatment with PCI."

Angioplasty and stenting are highly successful procedures for treating a heart attack, thanks to impressive improvements in devices, techniques, medications, and rapid treatment protocols.

In PCI, an interventional cardiologist makes a small puncture in the groin and introduces a slender tube, or catheter, into the femoral artery. The catheter is threaded up through the aorta and into the arteries that supply blood to the heart. After removal of the blood clot that is responsible for the heart attack, the cardiologist positions a small balloon across the remaining blockage and inflates the balloon to widen the artery. Another balloon with a stent crimped on it is positioned across the lesion and inflated, expanding and releasing the tiny metal tube that will act as scaffolding to keep the artery open.

In the first study, Dr. Ben-Dor and his colleagues analyzed data from 1,853 patients who had a type of heart attack known as ST-elevation myocardial infarction (STEMI) and were treated with PCI between 2000 and 2008. The overall success rate was 96.2%. When researchers analyzed characteristics that were independently linked to procedural failure, they found the most ominous to be lesions that were complex, calcified, widespread, or difficult-to-treat. These unfavorable characteristics hiked the risk of failure nearly fourfold. Simply being female increased the odds of procedural failure by a factor of 2.04.

PCI failure also resulted in significantly higher rates of death during the initial hospitalization (17.8% vs. 3.2%; p<0.001) and over the following year (44.7% vs. 13.0%, p<0.001). After PCI failure, patients were also more likely to suffer another heart attack within a year (20.0% vs. 8.1%, p=0.05) and to need a repeat procedure to open the artery blocked during the heart attack (23.1% vs. 8.3%, p=0.02).

Dr. Ben-Dor and his colleagues are continuing to investigate why women are at a disadvantage in heart attack PCI. They are currently analyzing some 800 arterial x-rays, or angiograms, taken in men and women experiencing a heart attack. The angiograms will help determine whether the explanation lies in the location of the obstructing lesion, or in lesion characteristics such as calcification, length, the number of twists and turns in the obstructed artery, and the amount of the blood clot blocking the artery.

For the second study, researchers at Zhongshan Hospital in Shanghai analyzed data from 692 consecutive patients who had a STEMI heart attack and were treated with PCI. Of these, 142 were women and 550 were men. Overall, 63% of patients were considered elderly (older than 60 years), but the proportion was much higher in women than in men (88.5% vs.56.5%, p=0.000). The average age of female patients was 71.1 years, as compared to 62.4 years for men (p=0.000). Women were also more likely to be diabetic (26.6% vs.18.4%, p=0.03). Rates of multivessel disease were similar in the two groups, as was the specific location of the arterial blockage that caused the heart attack. Other features, however, made PCI more challenging in women.

"In clinical practice, older females have more three-vessel disease, more calcified or tortuous lesions, and the arteries are smaller," said Junbo Ge, MD, a professor of medicine at Fudan University; director of cardiology at Zhongshan Hospital; and co-chairman of the Shanghai Institute of Cardiovascular Diseases, all in Shanghai, China. "All of these characteristics create technical difficulties and challenges in performing PCI in women, easily causing more complications and suboptimal results."

Indeed, Dr. Ge and his colleagues found that PCI was less successful in restoring full blood flow through the treated artery in women than in men, as indicated by the average "TIMI" score (2.8 vs. 2.9, p=0.048). In addition, women required a longer hospital stay (14.5 days vs.12.4 days, on average, p=0.02). The rates of serious complications, such as stroke, major bleeding and repeat heart attack during the initial hospitalization were similar in the two groups, but the in-hospital death rate in women was significantly higher, 12.8% vs. 5.4% in men, p=0.003.

The investigators concluded the survival disadvantage among women might be explained by their older age and less desirable PCI results.

"We need a large prospective study to confirm these findings and to determine why the final TIMI flow through the coronary artery was worse in female patients," Dr. Ge said. "Also, we should use new therapies, PCI devices, and strategies to further improve survival in women."

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