TY - JOUR
T1 - Myocardial infarction and atrial fibrillation
T2 - Importance of atrial ischemia
AU - Alasady, Muayad
AU - Shipp, Nicholas J.
AU - Brooks, Anthony G.
AU - Lim, Han S.
AU - Lau, Dennis H.
AU - Barlow, David
AU - Kuklik, Pawel
AU - Worthley, Matthew I.
AU - Roberts-Thomson, Kurt C.
AU - Saint, David A.
AU - Abhayaratna, Walter
AU - Sanders, Prashanthan
PY - 2013/8
Y1 - 2013/8
N2 - Background-Myocardial infarction (MI) is associated with the development of atrial fibrillation (AF). We aimed to characterize the atrial abnormalities because of MI and determine the role of ischemia to the AF substrate. Methods and Results-Forty-four sheep were studied. MI was induced by occlusion of the left circumflex artery (LCX) or left anterior descending artery (LAD). Excluding 11 with fatal arrhythmias, equal groups of animals (LCX; LAD; and sham-operated) underwent sequential electrophysiology study for 45 minutes to determine atrial effective refractory periods, conduction velocity, conduction heterogeneity index, and AF inducibility. Postmortem evaluation was performed with 2,3,5 triphenyl tetrazolium chloride staining. MI resulted in greater left ventricular dysfunction (P<0.05), LA pressure (P<0.0003), and reduction in atrial effective refractory periods (P<0.0001) compared with control. 2,3,5 triphenyl tetrazolium chloride staining demonstrated that the left circumflex artery, and not the LAD, group had atrial infarction. The left circumflex artery group demonstrated the following compared with the LAD or control groups: greater slowing in atrial conduction velocity (P<0.0001 and P<0.001); increased absolute range of conduction phase delay (P<0.001 and P<0.001); increased conduction heterogeneity index (P<0.0001 and P<0.001); greater AF vulnerability (P<0.05 for both); and longer AF duration (P<0.05 for both). LAD group had modest but significant slowing in conduction velocity (P<0.01) but no change in conduction heterogeneity index or AF duration compared with control. Conclusions-Left ventricular infarction, which is known to result in atrial stretch, hemodynamic change, and neurohumoral activation, contributes partially to the atrial abnormalities in MI. Atrial ischemia/infarction results in greater atrial electrophysiological changes and propensity for AF forming the dominant substrate for AF in MI.
AB - Background-Myocardial infarction (MI) is associated with the development of atrial fibrillation (AF). We aimed to characterize the atrial abnormalities because of MI and determine the role of ischemia to the AF substrate. Methods and Results-Forty-four sheep were studied. MI was induced by occlusion of the left circumflex artery (LCX) or left anterior descending artery (LAD). Excluding 11 with fatal arrhythmias, equal groups of animals (LCX; LAD; and sham-operated) underwent sequential electrophysiology study for 45 minutes to determine atrial effective refractory periods, conduction velocity, conduction heterogeneity index, and AF inducibility. Postmortem evaluation was performed with 2,3,5 triphenyl tetrazolium chloride staining. MI resulted in greater left ventricular dysfunction (P<0.05), LA pressure (P<0.0003), and reduction in atrial effective refractory periods (P<0.0001) compared with control. 2,3,5 triphenyl tetrazolium chloride staining demonstrated that the left circumflex artery, and not the LAD, group had atrial infarction. The left circumflex artery group demonstrated the following compared with the LAD or control groups: greater slowing in atrial conduction velocity (P<0.0001 and P<0.001); increased absolute range of conduction phase delay (P<0.001 and P<0.001); increased conduction heterogeneity index (P<0.0001 and P<0.001); greater AF vulnerability (P<0.05 for both); and longer AF duration (P<0.05 for both). LAD group had modest but significant slowing in conduction velocity (P<0.01) but no change in conduction heterogeneity index or AF duration compared with control. Conclusions-Left ventricular infarction, which is known to result in atrial stretch, hemodynamic change, and neurohumoral activation, contributes partially to the atrial abnormalities in MI. Atrial ischemia/infarction results in greater atrial electrophysiological changes and propensity for AF forming the dominant substrate for AF in MI.
KW - Acute coronary syndrome
KW - Atrial fibrillation
KW - Myocardial infarction
KW - Myocardial ischemia
KW - Remodeling
UR - http://www.scopus.com/inward/record.url?scp=84884529834&partnerID=8YFLogxK
U2 - 10.1161/CIRCEP.113.000163
DO - 10.1161/CIRCEP.113.000163
M3 - Article
SN - 1941-3149
VL - 6
SP - 738
EP - 745
JO - Circulation: Arrhythmia and Electrophysiology
JF - Circulation: Arrhythmia and Electrophysiology
IS - 4
ER -