Women less likely to survive heart bypass surgery

By Amy Norton

NEW YORK (Reuters Health) – Women are nearly twice as
likely as men to die from complications of heart bypass
surgery, and their typically smaller body size may be one of
the reasons, according to a study published Tuesday.

In a review of records for 15,440 patients who had
undergone coronary artery bypass grafting (CABG), researchers
found that 4.24 percent of women died during or immediately
after surgery, versus 2.23 percent of men, a statistically
significant difference.

The main reasons for the gender gap were the higher rates
of “traditional risk factors” among women, said lead study
author Dr. Ron Blankstein. In general, the study found, women
were older and more likely than men to have problems such as
diabetes and advanced heart failure.

But another factor was body size. Patients with a
relatively smaller “body surface area” were at greater risk of
dying from heart bypass surgery, and in general, women have
smaller bodies than men.

Body surface area is an indication of the size of a
person’s coronary arteries, and smaller vessels can make the
surgery “technically more difficult,” explained Blankstein, a
cardiology fellow at the University of Chicago Hospitals.

This fact, he and his colleagues speculate, may be why
smaller body size was linked to poorer survival.

However, body size and traditional risk factors did not
fully explain the higher death risk among female patients,
Blankstein told Reuters Health.

“Just being female is itself a risk factor,” he said. “We
need to figure out why this is.”

Blankstein and his colleagues report their findings in the
annual Cardiovascular Surgery Supplement of Circulation, a
journal published by the American Heart Association.

During CABG, a surgeon takes blood vessels from a patient’s
leg or elsewhere in the body and uses them to reroute blood
around a blockage in the arteries that normally supply the
heart. Though coronary artery disease can often be managed with
drug therapy or angioplasty — a less invasive procedure that
opens up clogged arteries — some patients require CABG.

Blankstein said that while the new findings are “sobering,”
they should not discourage women from having the surgery if
they need it.

“For a lot of women,” he noted, “bypass still represents
the best option for their disease.”

The study involved patients who underwent CABG at one of 31
hospitals in the Midwestern U.S. in 1999 and 2000. Overall,
women were 90 percent more likely than men to die during or
soon after surgery.

When the researchers accounted for a variety of potential
risk factors, including age, co-existing diseases and body
size, the gender gap narrowed substantially. Still, women
remained 22 percent more likely to die compared with men.

It will be important to find out why this discrepancy
persists even when standard risk factors are considered,
Blankstein said.

Some open questions, according to the researchers, are
whether body fat plays a role, since it affects healing in
tissues and blood vessels, and whether hormonal differences
between women and men could be at work.

SOURCE: Circulation, Cardiovascular Surgery Supplement,
August 30, 2005.