Does the anatomical shape of the heart present as a risk factor for "off-pump" coronary surgery?

Aim: Emergency conversion to on-pump during coronary surgery is known to increase morbidity and mortality in patients undergoing off-pump coronary surgery. We aimed to investigate the relation between the anatomical position of the heart and the incidence of conversion to on-pump coronary surgery. Material and Methods: Four hundred patients, who underwent off-pump three-vessel coronary surgery during June 2010 and February 2020. The angle between the left anterior descending (LAD) artery and the left arm of the sternal retractor was used to identify the anatomical position of the heart intraoperatively after pericardiotomy. Patients were categorized as having either transvers (Position Angle> 45°, n:200) or vertical (Position Angle <45°, n:200) heart. Results: The conversion rate was 8.75% (35/400) in our study. Thirty-three of patients with transverse heart patients converted to on-pump surgery (16.5%), whereas the two patients(1%) in patients with vertical heart. The length of intensive care unit stay was longer in patients with conversion compared to the patients with no conversion (3.17±1.10 days and 1.11±0.11 days, respectively) (p=0.001). Inotropic support and blood transfusion requirements were higher in converted patients. The mortality rate was 14.2% in converted patients while non-converted patients had no mortality (p<0.001). Conclusion: Conversion from off to on-pump during coronary surgery may cause high incidence of morbidity and mortality. Probable causes responsible for conversion should be predicted before making a decision for off-pump surgery. Anatomically transverse position of the heart may be considered as a potential predictor of conversion.