1 in 10 Canadians will benefit from improved diagnosis and treatment
Canadian scientists have determined that routine electrocardiogram (ECG) results for patients with atrial fibrillation (AF) - the most common form of irregular heart beat - can help doctors identify those at higher risk of adverse cardiovascular outcomes, including death. This knowledge will help doctors improve the treatment and prognosis of atrial fibrillation.
Through a retrospective analysis of thousands of patient files, researchers at the Montreal Heart Institute and the University of Calgary learned that a routine 12-lead surface ECG - in which 12 different electrical signals are recorded - conducted at the time of AF diagnosis is an accurate predictor of later adverse events.
Research presented today at the Canadian Cardiovascular Congress found that patients with AF do not all face the same risks for disease; determining the extent to which any individual patient is at risk of adverse events has been a challenge for doctors, until now.
"The ECG has recently received resurging attention due to its simplicity, relatively cheap cost and near universal availability," says Dr. Jason Andrade, cardiologist at the Montreal Heart Institute. "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."
ECG is used to measure the rate and regularity of heartbeats, as well as the size and position of the chambers, the presence of any damage to the heart and the effects of drugs or devices used to regulate the heart, such as a pacemaker
Researchers found that the strongest indicators of risk were prolonged QRS duration and prolonged PR and QT intervals, each of which is a measure of electrical waves that regulate heart rhythm.
For example, a prolonged QRS duration is associated with an increased risk of multiple adverse cardiovascular outcomes including death and hospitalization.
An increased PR interval is associated with cardiovascular death and sudden cardiac death. A prolonged corrected QT interval is associated with an increased risk of cardiovascular hospitalization and sudden arrhythmic death in men.
Dr. Andrade noted that the research team was "somewhat surprised at the strength of the relationship between the identified ECG predictors and the adverse cardiovascular outcomes."
Their data analysis showed that a prolonged QRS duration was associated with a 40 per cent increased risk for all-cause mortality, a 50 to 60 per cent increased risk for cardiovascular mortality and a 90 to 120 per cent increased risk for sudden cardiac death.