Effect of diabetes and associated conditions on long-term survival after coronary artery bypass graft surgery.

BACKGROUND: The effects of diabetes on short-term results of coronary artery bypass graft (CABG) surgery are known, but less is known about the long-term effects of diabetes and diabetic-related sequelae for patients undergoing this surgery. We studied the 10-year survival of nondiabetic and diabetic patients undergoing CABG surgery. METHODS AND RESULTS: A prospective regional cohort study was conducted of 36,641 consecutive isolated CABG patients in northern New England from 1992 through 2001. Patient records were linked to the National Death Index to assess mortality. There were 154,140 person-years of follow-up and 5779 deaths. Kaplan-Meier techniques were used. Survival was stratified into three categories: no diabetes, diabetes without peripheral vascular disease and renal failure, and diabetes with peripheral vascular disease and/or renal failure. The overall annual incidence rate of death was 3.7 deaths per 100 person-years. Annual incidence rates for nondiabetic subjects and diabetic subjects were similar: 3.1 deaths per 100 person-years and 4.4 deaths per 100 person-years, respectively. The annual incidence rate for diabetic subjects with renal failure, peripheral vascular disease, or both was 9.4 deaths per 100 person-years. The log-rank test showed that the survival curves were significantly different (P<0.001). CONCLUSIONS: Patients that have diabetes without the sequelae of renal failure and/or peripheral vascular disease have long-term survival similar to but slightly less than patients without diabetes who undergo CABG surgery. Survival of CABG surgery patients with diabetes is greatly affected by associated comorbidities of peripheral vascular disease and renal failure. This knowledge may help guide the patient as well as the cardiologist and cardiac surgeon in making appropriate decisions in these critically ill patients.

Determination of etiologic mechanisms of strokes secondary to coronary artery bypass graft surgery.

BACKGROUND AND PURPOSE: Current research focused on stroke in the setting of coronary artery bypass graft (CABG) surgery has missed important opportunities for additional understanding by failing to consider the range of different stroke mechanisms. We developed and implemented a classification system to identify the distribution and timing of stroke subtypes. METHODS: We conducted a regional study of 388 patients with the diagnosis of stroke after isolated CABG surgery in northern New England from 1992 to 2000. Data were collected on patient and disease characteristics, intraoperative and postoperative care, and outcomes. Stroke etiology was classified into 1 of the following: hemorrhage, thromboembolic (embolic, thrombotic, lacunar), hypoperfusion, other (subtype not listed above), multiple (>or=2 competing mechanisms), or unclassified (unknown mechanism). The reliability of the classification system was determined by percent agreement and kappa statistics. RESULTS: Embolic strokes accounted for 62.1% of strokes, followed by multiple etiologies (10.1%), hypoperfusion (8.8%), lacunar (3.1%), thrombotic (1.0%), and hemorrhage (1.0%). There were 54 strokes with unknown etiology (13.9%). There were no strokes classified as "other." Nearly 45% (105/235) of the embolic and 56% (18/32) of hypoperfusion strokes occurred within the first postoperative day. CONCLUSIONS: We used a locally developed classification system to determine the etiologic mechanism of 388 strokes secondary to CABG surgery. The principal etiologic mechanism was embolic, followed by stroke having multiple mechanisms and hypoperfusion. Regardless of mechanism, strokes predominantly occurred within the first postoperative day.

Long-term survival of dialysis patients after coronary bypass grafting.

BACKGROUND: Dialysis patients are undergoing coronary artery bypass grafting (CABG) with increasing frequency. The long-term effect of preoperative dialysis-dependent renal failure on mortality after CABG has not been well studied. METHODS: We conducted a prospective regional cohort study of 15,574 consecutive patients undergoing isolated CABG in northern New England from 1992 to 1997. Patient records were linked to the National Death Index to assess mortality. Five-year survival and adjusted hazard ratios were calculated. RESULTS: During 32,589 person-years of follow-up 1298 deaths were recorded. Renal failure was present in 283 patients (1.8%), and 67.8% of patients with renal failure also had diabetes or peripheral vascular disease (PVD). The annual death rate was 3.8% for nonrenal failure patients, 16.9% for all renal failure patients, 7.7% for renal failure patients without diabetes or PVD, and 23.0% for renal failure patients with diabetes or PVD. Five-year survival was 83.5% for nonrenal failure patients, 55.8% for all renal failure patients, 78.5% for renal failure patients without diabetes or PVD, and 42.2% for renal failure patients with diabetes or PVD. After adjustment for differences in base line patient and disease characteristics, renal failure patients without diabetes or PVD had a statistically nonsignificant 57% increase rate of death compared with those without renal failure; renal failure patients with diabetes or PVD had more than a fourfold increased risk of death. CONCLUSIONS: After adjustment for other risk factors, renal failure remains a highly significant predictor of decreased long-term survival in CABG patients. Patients with renal failure plus diabetes or PVD are at especially high risk of death.

Intra- and postoperative predictors of stroke after coronary artery bypass grafting.

BACKGROUND: Stroke is a devastating complication of coronary artery bypass graft surgery. An individual's risk of stroke is based in part on preoperative characteristics but also on intra- and postoperative factors. We developed a risk prediction model for stroke based on factors in intra- and postoperative care, after adjusting for a patient's preoperative risk. METHODS: We conducted a regional prospective study of 11,825 consecutive patients undergoing coronary artery bypass graft surgery surgery from 1996 to 2001. Data were collected on patient and disease characteristics, intra- and postoperative care and course, and outcomes. Stroke was defined as "a new focal neurologic deficit which appears and is still at least partially evident more than 24 hours after its onset." Logistic regression identified significant predictors of stroke. RESULTS: The incidence of stroke was 1.5%. The regression model significantly predicted the occurrence of stroke. As compared with cardiopulmonary bypass for less than 90 minutes, cardiopulmonary bypass for 90 to 113 minutes, odds ratio = 1.59, p = 0.022), cardiopulmonary bypass for 114 minutes or more (odds ratio = 2.36, p < 0.001), atrial fibrillation (odds ratio = 1.82, p < 0.001), and prolonged inotrope use (odds ratio = 2.59, p = 0.001) significantly improved our ability to predict stroke. Nearly 75% of all strokes occurred among the 90% of patients at low or medium preoperative risk. CONCLUSIONS: The inclusion of factors associated with intra- and postoperative care and course significantly improved the prediction model. Most strokes occurred among patients at low or medium preoperative risk, suggesting that many of these strokes may be preventable. Reduction in stroke risk may require modifications in intra- and postoperative care and course.

Intraoperative and postoperative variables associated with strokes following cardiac surgery.

BACKGROUND: Strokes are a devastating complication of coronary artery bypass grafting (CABG) surgery. Previous work from 1992 to 2000 determined the principal mechanism of strokes occurring secondary to CABG. In the present study, we quantified the association between intraoperative and postoperative variables and stroke mechanisms while adjusting for patient and disease characteristics. METHODS: We conducted a prospective study of 13,897 patients who underwent isolated CABG in northern New England from 1992 to 2000. Data were collected on patient and disease characteristics, intraoperative and postoperative care, and outcomes. Strokes were classified as embolic, hypoperfusion, and mixed (hemorrhage, lacunar, thrombotic, other, multiple, and unclassified). We quantified the association between the intraoperative and postoperative treatment and course variables and the stroke mechanism while adjusting for patient and disease characteristics. Patients without strokes served as the reference group for the determination of odds ratios (OR). RESULTS: Variables associated with embolic strokes included cardiopulmonary bypass time greater than 2 hours versus less than 1 hour (OR, 1.5; ptrend.03) and postoperative atrial fibrillation (OR, 2.4; P <.001). The risk of hypoperfusion strokes was increased with the duration of cardiopulmonary bypass (OR, 6.4; ptrend.01) and postoperative atrial fibrillation (OR, 5.4; P <.001). Postoperative atrial fibrillation was associated with the risk of mixed strokes (OR, 1.7; P =.04). CONCLUSIONS: After we adjusted for preoperative factors, postoperative atrial fibrillation and increasing duration of cardiopulmonary bypass remained significant predictors of embolic and hypoperfusion strokes, although to differing degrees. Prevention and management of atrial fibrillation and avoidance of prolonged exposure to extracorporeal circulation may offer leverage areas for the improvement of stroke outcomes.