P&S Journal: Winter 1998, Vol.18, No.1
Heart Transplants or Bypass Surgery?
Using PET scanning, nuclear cardiologists at P&S have found that as many as 40 percent of patients thought to need a heart transplant can be treated successfully with bypass surgery.
"The importance of this study is that we can probably remove a lot of the people from the heart transplant waiting list," says Dr. Steven Bergmann, professor of medicine and of radiology. "And then those who truly need a donor heart will have better odds of getting one."
In 1996, 3,698 people were on the waiting list for a heart transplant, yet only 2,342 donor hearts became available, according to the United Network for Organ Sharing.
The study involved 20 patients who were diagnosed with end-stage heart disease through conventional diagnostics, including thallium exercise stress tests. The patients underwent PET scans, which not only provide a more detailed picture of cardiac blood flow than thallium scans, but also show metabolic activity in heart muscle. Eight patients were found to have viable myocardium and blocked coronary arteries, indications that they might benefit from a bypass. Of these eight, seven underwent surgery.
"All seven did extremely well," reports Dr. Bergmann. "They recovered relatively quickly, and their ejection fraction, a measure of the heart's pumping power, improved significantly." On average, the ejection fraction (EF) of these patients increased from 22 percent to 33 percent, and one patient's EF reached 47 percent. Normal EF is between 55 percent and 60 percent.
It is not known how the bypass patients will do in the long run, but all seven are doing well a year or more after surgery. By comparison, the mortality rate of people on the heart transplant waiting list is about 60 percent per year.
Surgeons have been relatively reluctant to operate on people with poor ventricular function because they don't tolerate the surgery very well," Dr. Bergmann says. But we've shown that if they have enough viable myocardium, they'll do well with surgery.
Two of the 20 patients had non-viable myocardium, according to PET scanning. Both underwent bypass surgery and ultimately needed a transplant.So PET was a good discriminator of who would respond well to revascularization, Dr. Bergmann says.
The findings of the study were presented by Dr. Olakunle Akinboboye, assistant professor of clinical medicine, at the annual meeting of the Society of Nuclear Medicine.
Dr. Bergmann cautions that a larger study, now under way at Columbia-Presbyterian, is needed to confirm the results.