Study: CAD may be predictor of AF onset after MI

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While atrial fibrillation (AF) is the most common cardiac arrhythmia, the pathology of the disease in the acute setting of MI remains unknown. A single-center study published earlier this month in July’s Heart Rhythm Journal found that coronary artery disease (CAD) affecting the atrial branches may be an independent predictor for the development of AF.

During the study, Muayad Alasady, MBChB, of the University of Adelaide and the Royal Adelaide Hospital in Adelaide, Australia, and colleagues identified 2,460 patients who presented to the Flinders Medical Centre's cardiac care unit in Bedford Park, Australia, with acute MI between 2004 and 2009. The reserachers evaluated the development of a new onset of AF.

Of the cohort, 149 patients developed AF within seven days of MI. The researchers identified 42 AF patients whose coronary anatomy was evaluated by invasive angiography and whose cardiac function was tested using transthoracic echo. The researchers studied 42 patients with MI but no AF as controls.

The researchers reported that patients with AF were more likely to present with an inferior MI but less likely to present with STEMI. Alasady et al found that patients with AF had more cases of left main stem disease and right CAD compared to controls.

Most significantly, more AF patients had at least one significant atrial branch with reduced flow compared to controls: right coronary artial branch—66.7 percent vs. 19 percent; and left circumflex atrial branches—43 percent vs. 17 percent. Additionally, the researchers found that 50 percent of AF cases had reduced circulation to the sinoatrial nodal branch compared to 24 percent of controls.

The authors concluded that right coronary atrial branch disease and left circumflex atrial branch disease were independent predictors of a new onset of AF during the first week post-MI after the authors adjusted for LA volume index and TIMI flow post-PCI.

“Coronary artery disease affecting the atrial branches, possibly due to atrial ischemia, was associated with promotion of AF genesis, regardless of whether it originated from the left or right coronary system,” the authors wrote.

“Together with the angiographic data, our echocardiographic findings have provided novel insights into the mechanisms underlying the development of AF after MI.

“Our findings indicate that atrial branch disease remained a predictor of AF even after adjustment for E/e=, 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,” the authors noted.

“With the angiographic data and echocardiographic findings, our results provide novel insight into the mechanisms underlying the development of AF in patients after they experience a heart attack,” Prashanthan Sanders, MBBS, PhD, the study’s senior author concluded. “The findings shed new light on how coronary disease affects the atrial branches after the trauma of a heart attack regardless of measurable effects such as a patient’s gender or age.”