November 17, 2003

Rhythm and Rate Control Get Similar Results
By Mike Upchurch

A DCRI study shows that controlling the heart’s rate can save as many lives as treating its rhythm, when dealing with patients who have atrial fibrillation as well as congestive heart failure.

Lead author Dr. Sana Al-Khatib presented the results of an analysis gleaned from the massive Duke Databank for Cardiovascular Disease at the annual scientific sessions of the American Heart Association on November 10. The study analyzed 739 patients with atrial fibrillation, in which the upper chambers of the heart pump erratically, and who also had congestive heart failure (CHF), which limits the heart’s ability to pump adequate amounts of oxygen-rich blood to the rest of the body. CHF compounds an atrial fibrillation patient’s risk of death or stroke.

Atrial fibrillation can be treated either with electric shock to restore a normal rhythm or with antiarrhythmic drugs, such amiodarone. The condition can also be treated by trying to reduce the heart rate with beta-blockers or digoxin.

Patients in the analysis whose treatment focused on restoring a normal rhythm did not fare any better than those who were treated via rate control. Rhythm control, however, did have worse rates of side effects. These results confirm the findings of the AFFIRM trial, which enrolled over 4000 patients with atrial fibrillation in the U.S. and Canada. About one quarter of those patients also had CHF.

“However, AFFIRM did not definitively address the important issue of how these 2 strategies affect the outcome of patients who have CHF as well as atrial fibrillation,” said Al-Khatib. “This is an important subgroup because of their elevated risk.”

“Only 23% of patients enrolled in AFFIRM had a history of CHF," Al-Khatib continued. "Thus it was not determined whether rhythm-control therapy is superior to rate-control therapy for this group of patients.”

Al-Khatib’s study found that, despite no hard evidence on its advantages, antiarrhythmic treatment increased from around 30% in 1995 to more than 67% in 2002.

“While our data show the use of antiarrhythmic drugs becoming more widespread, there remains some controversy over the best way to medically treat atrial fibrillation,” Al-Khatib said. "When we adjusted for the baseline variables, we found no difference in survival between the 2 strategies.”

A Canadian trial called the Atrial Fibrillation and Congestive Heart Failure trial hopes to fill the gap in our knowledge of treating this deadly combination of diseases. It will enroll nearly 1500 patients in the U.S., Canada, South America and Europe and compare the mortality rates of both treatment approaches.

“Finding answers to these questions will become increasingly important because with the aging of the American population, clinicians will see more patients with atrial fibrillation," Al-Khatib said. “We not only want to be able to improve the life expectancy for these patients, but also to take into account their quality of life.”

Joining Dr. Al-Khatib from the DCRI on this study were biostatistician Linda Shaw and Drs. Monica R. Shah, Chris toper M. O’Connor, and Robert M. Califf.