左室補助装置の進歩（Abstract # 1762）

A new left ventricular assist device the size of a battery means that more women and short men with slim builds may be able to benefit from the technology while awaiting transplants, according to a presentation at the annual meeting of the American Heart Association.

“The fact that we have a technology where the outcomes in women are equal to men is important,” said Roberta C. Bogaev, MD, lead author of the study and medical director of heart failure and cardiac transplantation at the Texas Heart Institute in Houston.

“Historically, because of their size, such devices have been unavailable to women of small stature. Now that we have a pump about the size of a D battery, it will allow us to expand mechanical circulatory support options to more women.”

The device, The HeartMate II, is powered by a battery-run unit worn outside the body.
The U. S. Food and Drug Administration is reviewing the manufacturer’s request to approve use of the experimental pump in heart failure patients.

In the current, phase II study, participants received the device as a bridge to assist ventricular function until a donor heart became available. The trial involved 231 patients with advanced heart failure, 52 (23 percent) of them women, who were treated at 40 heart transplant centers in the United States.

“This is the first trial to include this many women,” said Bogaev. “Most ventricular assist device trials before HeartMate II enrolled less than 10 percent women.”

Women in the study were 20 to 69 years old (average, 56 years), while men were 17 to 68 years (average, 54 years). The cause of heart failure was more likely to be coronary artery disease in men (43 percent) than in women (31 percent). The women tended to have suffered a weakened heart because of pregnancy, cancer chemotherapy, viral infection, or unknown cause.

Some study participants - six at the Texas Heart Institute alone - recovered sufficient
ejection fraction that the device was removed successfully.

For the 194 patients with six-month follow-up data, survival was 79.5 percent for women and 80.6 percent for men. This included patients who had undergone a heart transplant, had their device removed after regaining ventricular function, or remained on the device. The average duration on the pump was 175 days for women (range, 8 to 667 days) and 130 days for men (range, 0 to 693 days).

A loss of right ventricular ejection fraction requiring temporary implantation of a right ventricular device occurred in 10 patients, 9 percent of women and 4 percent of the men.

“What that suggests to me is that the women enrolled in this trial may have presented with more advanced heart failure,” Bogaev said. “Now that we have the option of a smaller device, physicians should not delay in referring women for ventricular assist devices.”

Six patients, 3.3 percent of women and 2.2 percent of men, experienced strokes within two days after their surgery. Twelve patients (13.6 percent of women and 5 percent of men) experienced strokes more than two days after surgery.

“Since this is a small number of patients, we will need to continue to follow patients with this device to determine if this is a significant finding between men and women,” Bogaev said.

After three months of left ventricular assistance, 76 percent of women and 57 percent of men had increased the distance they could walk in six minutes by more than 200 meters.

At three months, 84 percent of women and men had New York Heart Association Class I
and Class II heart failure symptoms compared with Class IV symptoms for all participants at baseline.

The 11 smallest patients receiving the device were women, and all were alive at the six-month follow-up.

“This smaller device is well suited for women and small men, who previously have not had the option of mechanical circulatory support,” Bogaev said. “At the Texas Heart Institute, we’ve been able to increase the percentage of women who benefit from left ventricular assist devices from 7 percent to 37 percent.”