ECG results in AF patients predict adverse outcomes

Results from routine electrocardiograms (ECGs) in patients with atrial fibrillation (AF) can accurately predict later adverse events, researchers reported Oct. 28 at the Canadian Cardiovascular Congress in Toronto.  

Jason G. Andrade, MD, of the Montreal Heart Institute, and colleagues conducted a combined post hoc analysis based on two trials: AFFIRM (Atrial Fibrillation Follow-Up Investigation of Rhythm Management), a multicenter, randomized trial that compared rate-control therapy with rhythm-control therapy to treat AF in patients at  high risk of stroke or death; and AF-CHF (Atrial Fibrillation and Congestive Heart Failure), which compared restoring and maintaining sinus rhythm with optimizing ventricular rate in patients with AF and congestive heart failure.

The post hoc analysis used data on 5,436 patients randomized to rhythm- or rate-control therapy and included 7,159 baseline ECGs. The outcomes under study were cardiovascular mortality, all-cause mortality, arrhythmic death, time to first hospitalization, and time to first cardiovascular hospitalization. Separate analyses were performed in AF and in sinus rhythm.

They found that increased QRS duration was significantly and independently associated with all-cause mortality, cardiovascular death, arrhythmic death, any hospitalization and cardiovascular hospitalization. An increased PR interval was significantly and independently associated with cardiovascular and arrhythmic mortality. They defined increased QRS duration as 120 milliseconds or more and increased PR as more than 200 milliseconds.

“The ECG has recently received resurging attention due to its simplicity, relatively cheap cost and near universal availability,” Andrade said in a release. “This knowledge, combined with the recognition that all patients with AF will receive an ECG as part of their diagnostic work-up, makes it highly useful as a method for assessing risk.”

Based on their analysis, the researchers determined that a prolonged QRS duration was associated with a 40 percent increase in risk for all-cause mortality, a 50 to 60 percent increase in risk for cardiovascular mortality and a 90 to 120 percent increase in risk for sudden cardiac death.

The researchers were “somewhat surprised at the strength of the relationship between the identified ECG predictors and the adverse cardiovascular outcomes,” Andrade said.

They concluded that simple parameters on baseline ECG significantly and independently predicted adverse cardiovascular outcomes in patients with a history of AF.