Predictors and Outcomes Conversion to Sternotomy in Minimally Invasive Coronary Artery Bypass Grafting
Maria L. Rodriguez, Harry Lapierre, Benjamin Sohmer, Jean-Philippe Ruel, Dominique Menard, Marc Ruel.
University of Ottawa Heart Institute, Ottawa, ON, Canada.
OBJECTIVE: To identify the determinants of conversion of Minimally Invasive Coronary Artery Bypass Grafting (MICS CABG), with and without cardiopulmonary bypass (CPB) assistance, to sternotomy, and compare clinical outcomes in patients who needed conversion.
METHODS: A retrospective observational study was performed in patients (n=266) who underwent MICS CABG by a single surgeon. We classified patients who underwent MICS CABG off-pump as Group A (n=194; 73%). Group B were MICS CABG patients supported with CPB (n=59; 22%). Group C were patients planned for MICS CABG off-pump who had to be emergently assisted with CPB (n=3; 1%). Group D were planned as MICS CABG off-pump and had to be converted to sternotomy (n=9; 3%). Group E underwent MICS CABG with CPB assistance but still necessitated sternotomy (n=1; 0.4%).
RESULTS: The average age was 62 years (range 36-86), with male predominance (86%). The average BSA was 1.9±0.2 m2 (range 1.4 - 2.6). LV function was normal in 70%. The median number of bypassed territories was 2, higher in those who underwent CPB (median 3 grafts; P=0.01). Predictors for use of CPB included diabetes, 3-vessel disease, left circumflex involvement, and small target vessels (P=0.04). Risk factors for conversion to sternotomy included ongoing smoking, preoperative bradycardia (<50 beats per minute), inability to tolerate one lung ventilation, inadequate surgical exposure causing LITA injury or non-optimal graft orientation, and hemodynamic instability. The average ICU length of stay (LOS) was 1.6±1.3 days. The mean hospital LOS was 5.9±5.8 days, and was longer for patients who had CPB and/or sternotomy (6.4±4.3 and 6.8±2.5 days, respectively; P≤0.05). Postoperative complications included superficial thoracotomy infection (3%), sternotomy infection (10%), new atrial fibrillation (3%), and need for blood transfusion (14%). Twelve patients (5%) developed left-sided pleural effusion that required drainage. There were no perioperative MACE or death.
CONCLUSIONS: MICS CABG is safe, with a low rate of conversion to sternotomy. Conversions may be alleviated by an effort to optimize modifiable risk factors and the adequacy of surgical exposure. These data may help develop objective selection criteria to identify patients who are excellent candidates for MICS CABG.
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