Peggy Peck

October 27, 2004

Oct. 27, 2004 (Seattle) — Patients who are in sinus rhythm after mitral valve repair are not at risk for stroke and therefore do not require the standard three-month course of warfarin (Coumadin) after surgery, according to a retrospective study.

Gerald M. Lawrie, MD, a clinical professor of surgery at Baylor College of Medicine in Houston, presented the results of the study in an oral abstract presentation here at CHEST 2004, the 70th annual meeting of the American College of Chest Physicians.

In a series of 561 patients who underwent mitral valve repair at the Methodist Hospital in Houston, 294 patients in sinus rhythm after surgery were discharged without warfarin. During 15 years of follow-up, "only 2% of the sinus rhythm patients developed stroke, and none of those strokes — not a single one — occurred during the first six months postprocedure, the 'early stroke' that Coumadin is supposed to prevent," Dr. Lawrie said.

Moreover, even patients with atrial fibrillation at discharge are unlikely to develop early stroke, and warfarin does little to prevent overall stroke risk in these patients, Dr. Lawrie added. In his series, the stroke rate for 101 atrial fibrillation patients discharged without warfarin was 5%, while for 81 atrial fibrillation patients discharged with warfarin, the stroke rate was 4.9%. "But again, none of these strokes occurred in the first six months after discharge," he said.

Based on this series, "at our institution, no patients are discharged on warfarin following mitral valve repair," Dr. Lawrie said.

"The only reason to use Coumadin is to prevent stroke," Dr. Lawrie told Medscape. "However, there are no studies that indicate patients in sinus rhythm are at risk of stroke. And even if there was a stroke risk, three months of Coumadin, which is the standard practice, would prevent early stroke. This series demonstrates that there is no early stroke risk, so there is no reason to inflict Coumadin on these patients."

Dr. Lawrie noted that eliminating warfarin "saves money and reduces risk associated with anticoagulation therapy."

The mean age of patients in the study was 62 ± 15 years, and 52% were men. Atrial fibrillation was present preoperatively in 31.4% of patients. Preoperative New York Heart Association class was III to IV in 52% of patients, and coronary artery disease was present in 37.4% of patients. The mean ejection fraction was 55%.

"Although this is a retrospective study, patients are followed prospectively," Dr. Lawrie said. During 15 years of follow-up, 17 strokes occurred; "usually strokes occurred about four years after surgery."

One hundred and eighty-two patients had atrial fibrillation at discharge and of these, 101 were discharged without warfarin. Two hundred and ninety-four sinus rhythm patients were discharged without warfarin, and 53 patients in sinus rhythm were given warfarin for three months after discharge.

There were five strokes in the atrial fibrillation patients discharged without warfarin and four strokes in the atrial fibrillation patients receiving warfarin at discharge. Of the sinus rhythm patients discharged without warfarin there were five strokes (1.7%), and there were two strokes (3.9%) in the sinus rhythm patients taking warfarin at discharge ( P = .05).

By Cox regression multivariate analysis, postoperative sinus rhythm was the strongest predictor of freedom from stroke ( P = .04).

Philip Corcoran, MD, chief of cardiothoracic surgery at Walter Reed Army Medical Center in Washington, D.C., told Medscape that Dr. Lawrie's findings are interesting, but he is not convinced. "I've had patients who stroked within six months of surgery, so I don't agree that there is no early stroke risk," he said.

Moreover, Dr. Corcoran said that "any time you go in and disrupt the endocardium, you have a risk of developing atrial fibrillation and a risk for stroke. That risk is there until the endothelial healing process is complete."

He noted, too, that mitral valve repair patients who are in atrial fibrillation preoperatively are likely to undergo a MAZE procedure for atrial fibrillation repair, a surgery that requires a complex series of incisions to interrupt electrical impulses. "When you go in and zap, burn, and cut the heart, the patient is going to need Coumadin — every patient," Dr. Corcoran said. In his institution, standard practice is to require warfarin for six to nine months postoperatively, he said.

CHEST 2004: Abstract 734S. Presented Oct. 26, 2004.

Reviewed by Gary D. Vogin, MD