Atrial branch disease linked to new-onset AF after MI
MedWire News: The risk for de-novo atrial fibrillation (AF) during acute myocardial infarction (MI) is increased in patients with atherosclerosis in the atrial branches of the coronary vasculature, Australian researchers report.
Prashanthan Sanders (Royal Adelaide Hospital) and team undertook a case-control study to evaluate the characteristics associated with new-onset AF following MI in a series of 2460 consecutive MI patients.
A total of 149 (6%) patients had AF at 7 days post-MI. After excluding patients with prior AF, heart failure, cardiac hypertrophy, reduced left ventricular (LV) ejection fraction, valvular heart disease, or pericarditis, there were 42 cases who underwent further detailed assessment.
Forty-two MI patients without AF, matched for age, gender, and LV ejection fraction, served as controls.
Writing in the journal Heart Rhythm, Sanders' team reports that cases and controls differed in two important respects, namely, AF patients had significantly higher left atrial volumes (40 vs 26 ml/m2) and significantly higher LV diastolic filling pressures (17 vs 11 E/e') than controls.
After multivariable analysis, there were just two independent predictors for new-onset AF after MI; right coronary atrial branch disease and left circumflex atrial branch disease.
Both remained significant predictors even after adjusting for LV diastolic filling pressures, "suggesting that in these patients with coronary artery disease, atrial ischemia may promote the formation of a substrate for AF that is independent of increased filling pressures," say the authors.
Furthermore, the increased left atrial size in patients with atrial branch disease "is probably due to both atrial ischemia and atrial stretch due to increased left atrial pressure."
The team concludes: "We have been able to observe clinical predictors for the frequent occurrence of AF in MI but have not evaluated the subsequent mechanisms or activation of the autonomic or humoral responses that may be attributed to MI."
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By Joanna Lyford