Correlation between Pre-Operative Myocardial Fibrosis and Early Post CABG Dysrhythmia

Background: Cardiac magnetic resonance (CMR) imaging combines the assessment of both the functional and structural aspects of the heart in order to identify the existence, timing, and intensity of ischemic heart disease by analyzing the function of the myocardium and the movement of the heart wall. This study aimed to investigate whether preoperative myocardial fibrosis, measured by CMR imaging, may be used to predict the incidence of rhythm disturbances in the early postoperative phase after coronary artery bypass grafting (CABG) surgery.

Methods: Two groups of 92 patients who had CABG procedures performed were studied in this retrospective observational single site cohort study: There were 43 patients in Group A who had atrial or ventricular arrhythmia, and 49 patients in Group B who did not.

Results: There was no correlation between arrhythmia and non-arrhythmia group and age, sex, body mass index, risk factor, CMR timing before surgery, cross clamp time, bypass time, left ventricular end-diastolic volume index (LV EDVI), LV end-systolic volume index (ESVI), stroke volume index (SVI), LV ejection fraction (EF) and territory of scar and were positive correlation between both groups and scar (P <0.001). Scar% was an independent predictor of occurrence of rhythm disturbance (P=0.002) while LV EDVI, LV EF, LV ESVI, SVI, and presence of scar were not. Group A had a statistically significantly lower LV-EF% and lower LV-SVI compared to Group B. Group A had a higher scar percentage compared with group B and this was statistically significant (P <0.001). Rhythm disturbance occurred more often in patients with a scar percentage >14.8% {P=0.0002 and area under ROC curve (AUC)=0.708}.

Conclusions: CMR has evolved as a gold standard non-invasive imaging tool in cardiovascular medicine. Preoperative CMR imaging may be a promising tool for predicting postoperative cardiac arrhythmia after CABG. Our study showed that preoperative myocardial scarring >14.8%, as determined by CMR imaging, was predictive of early postoperative arrhythmia in patients undergoing CABG.