Coronary Artery Bypass; Coronary Disease/surgery; Intra-Aortic Balloon Pumping; Intraoperative Care/methods; Patient Selection; Aged; Alabama/epidemiology; Analysis of Variance; Comorbidity; Coronary Artery Bypass/adverse effects; Coronary Artery Bypass/mortality; Coronary Disease/complications; Coronary Disease/mortality; Female; Follow-Up Studies; Hemodynamics; Humans; Intra-Aortic Balloon Pumping/methods; Intra-Aortic Balloon Pumping/statistics & numerical data; Length of Stay/statistics & numerical data; Logistic Models; Male; Postoperative Complications/etiology; Postoperative Complications/mortality; Postoperative Complications/prevention & control; Proportional Hazards Models; Risk Factors; Survival Analysis; Time Factors; Treatment Outcome