Standard ECG may help predict risk of future AF

STANFORD, CALIFORNIA. Most people in developed countries probably have one or more standard 12-lead electrocardiograms (ECG) during their lifetime. Now researchers at Stanford University School of Medicine report that data from these ECGs may be useful in predicting future risk of developing atrial fibrillation.

The researchers reviewed (using a computerized system) 137,000 ECG recordings obtained from 42,751 patients during the period March 1987 to July 2000. The patients were followed for an average of 5.3 years during which 1,050 of them (2.4%) developed AF verified by ECGs. Being male was found to be the strongest risk factor, increasing risk by a factor of 4.4. Age was also important with the average age of participants developing afib being 67.5 years vs. 55.8 years for those who remained in sinus rhythm. African-Americans had an increased risk of developing afib, while Hispanics had a lower risk when compared to white Caucasians.

In studying the baseline ECGs and correcting for possible confounding variables, the researchers conclude that the following factors significantly increase the risk of developing AF.

Variable(1)
Hazard Ratio
Presence of PACs(2)
2.1
Abnormal P axis
1.9
Pindex > 35 ms(3)
1.7
Pmax > 120 ms(4)
1.6
Presence of PVCs(5)
1.5
PR interval > 200 ms
1.3

(1) heartbeat101
(2) Premature atrial contractions
(3) Pindex is defined as the standard deviation of P-wave duration across the 12 leads and may reflect the heterogeneity of diseased atria.
(4) Maximum duration of the P-wave
(5) Premature ventricular contractions

The association between a high Pindex and AF risk was particularly strong in patients younger than 60 years (Hazard ratio of 5.3) and older than 90 years (Hazard ratio of 7.4). The researchers conclude that the Pindex, a measurement of disorganized atrial depolarization, is one of the strongest predictors of future atrial fibrillation.

Perez, MV, et al. Electrocardiographic predictors of atrial fibrillation. American Heart Journal, Vol. 158, No. 4, October 2009, pp. 622-28

Editor’s comment: The finding that a Pindex > 35 ms confers a 5-fold increase in the risk of developing afib among people below the age of 60 years may be of particular interest if future research establishes a correlation between Pindex and certain lifestyles, environmental or dietary factors. The authors of the paper make this interesting comment – “Atrial fibrillation has been growing at a pace rapid enough to be labeled an epidemic”. Perhaps the medical research fraternity needs to address the question “WHY?” with greater vigor!