Stephen J. Lahey

Risks of Morbidity and Mortality in Dialysis Patients Undergoing Coronary Artery Bypass Surgery

Background—Although dialysis patients are undergoing CABG with increasing frequency, large studies specifically comparing patient characteristics and procedure-related risks in this population have not been performed. Methods and Results—We conducted a regional prospective cohort study of 15 500 consecutive patients undergoing CABG in northern New England from 1992 to 1997. We used multiple logistic regression analysis to examine associations between preoperative dialysis-dependent renal failure and postoperative events and to adjust for potentially confounding variables. The 279 dialysis-dependent renal failure patients (1.8%) were 4.4 times more likely to experience in-hospital mortality than were other CABG patients (12.2% versus 3.0%, respectively;P <0.001). Dialysis-dependent renal failure patients were older and had more comorbidities and more severe cardiac disease than did other CABG patients. After adjusting for these factors in multivariate analysis, however, dialysis-dependent renal failure patients remained 3.1 times more likely to die after CABG (adjusted odds ratio [OR] 3.1, 95% CI 2.1 to 4.7;P <0.001). Dialysis-dependent renal failure patients compared with other CABG patients also had a substantially increased risk of postoperative mediastinitis (3.6% versus 1.2%, respectively; adjusted OR 2.4, 95% CI 1.2 to 4.7;P =0.011) and postoperative stroke (4.3% versus 1.7%, respectively; adjusted OR 2.1, 95% CI 1.1 to 3.9;P =0.016), even after controlling for potentially confounding variables. Risks of reexploration for bleeding were similar for patients with and without dialysis-dependent renal failure. Conclusions—Preoperative dialysis-dependent renal failure is a strong independent risk factor for in-hospital mortality and mediastinitis after CABG.

Mediastinitis and long-term survival after coronary artery bypass graft surgery

BACKGROUND Mediastinitis is a dreaded complication of coronary artery bypass surgery (CABG). The long-term effect of mediastinitis on mortality after CABG has not been well studied. METHODS We examined the survival of 15,406 consecutive patients undergoing isolated CABG surgery from 1992 through 1996. Patient records were linked to the National Death Index. Mediastinitis was defined as occurring during the index admission and requiring reoperation. RESULTS Mediastinitis occurred in 193 patients (1.25%). Patients with mediastinitis were older and more likely to have had emergency surgery, diabetes, peripheral vascular disease, chronic obstructive pulmonary disease, and preoperative dialysis-dependent renal failure. Patients with mediastinitis were also more likely to be severely obese and had somewhat lower preoperative ejection fraction. After multivariate adjustment for these factors, the first year post-CABG survival rate was 78% with mediastinitis and 95% without, and the hazard ratio for mortality during the entire follow-up period was 3.09 (CI 95% 2.28, 4.19; p < 0.0001). CONCLUSIONS Mediastinitis is associated with a marked increase in mortality during the first year post-CABG and a threefold increase during a 4-year follow-up period.

Review of Coronary-Subclavian Steal Following Internal Mammary Artery—Coronary Artery Bypass Surgery

The syndrome of coronary-subclavian steal through an internal mammary artery graft following coronary artery bypass grafting is rare. We are aware of only eight cases reported in the world literature. The cases of these 8 patients are reviewed, and the case of the ninth patient is described. All patients but 1 have been successfully managed by subclavian-carotid artery bypass.

Use of the Internal Mammary Artery Graft and In-Hospital Mortality and Other Adverse Outcomes Associated With Coronary Artery Bypass Surgery

Background —There is clear evidence that patients having coronary artery bypass graft surgeries with an internal mammary artery (IMA) have better long-term survival. Some studies have suggested a short-term protective effect as well but, because older and sicker patients are less likely to receive an IMA graft, there has been concern that the apparent protective effect of the IMA on short-term mortality has been confounded by other risk factors. This study was intended to examine the independent effect of IMA grafts on in-hospital mortality while adjusting for patient and disease factors. Methods and Results —We studied the use of the left IMA (LIMA) in 21 873 consecutive, isolated, first-time coronary artery bypass graft procedures from 1992 through 1999. A total of 87% of the patients received a LIMA graft. LIMA graft use was associated with a significantly decreased risk of mortality. The crude odds ratio for death (LIMA versus no LIMA) was 0.26 (95% confidence intervals, 0.22, 0.31;P <0.001). LIMA grafts were protective across all major patient and disease subgroups. The odds ratios by subgroup ranged from 0.13 to 0.48. After adjustment for all major risk factors, the odds ratio for death was 0.40 (95% confidence intervals, 0.33, 0.48;P <0.001). Rates of cerebrovascular accident, return to cardiopulmonary bypass, return to the operating room for bleeding, and mediastinitis or sternal dehiscence requiring surgery were also less in the LIMA group, although not significantly so. Conclusions —These data suggest that in addition to its well-documented patency and long-term beneficial effect, LIMA grafting has a strong protective effect on perioperative mortality.

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.

Improved in-hospital mortality in women undergoing coronary artery bypass grafting

BACKGROUND Few studies have examined the changes in in-hospital mortality for women over time. We describe the changing case mix and mortality for women undergoing coronary artery bypass grafting (CABG) from 1987 to 1997 in northern New England. METHODS Data were collected on 8,029 women and 21,139 men undergoing isolated CABG. The study consisted of three time periods (1987 to 1989, 1990 to 1992, and 1993 to 1997) to account for regional efforts to improve quality of care that occurred during 1990 to 1992. RESULTS Compared with 1987 to 1989, women undergoing CABG in 1993 to 1997 were older, had poorer ventricular function, and more often required urgent or emergency operations. The crude and adjusted mortality rates for both women and men decreased significantly over time. The absolute magnitude of the change in adjusted rates was greater for women (3.1%) than for men (1.5%). Although women represented only 28% of the study population, the decrease in their mortality accounted for 44% of the total decrease in adjusted mortality during the study period. CONCLUSIONS Over the last decade there has been a marked decrease in CABG mortality for women, despite a worsening case mix.

Trends in Rates of Reexploration for Hemorrhage After Coronary Artery Bypass Surgery

BACKGROUND While mortality rates associated with coronary artery bypass grafting (CABG) have been declining, it is unknown whether similar improvements in the rates of morbidity have been occurring. This study examines trends in reexploration rates for hemorrhage, one of the serious complications of CABG surgery. It also explores changes in patient characteristics and several surgeon practice patterns potentially related to bleeding risks that may explain variations in these rates. METHODS We performed a regional observational study of all of the 12,555 consecutive patients undergoing isolated CABG surgery in northern New England between 1992 and 1997. The rates of reexploration and patient characteristics were examined between two time intervals: period I (January 1, 1992 to June 1, 1994) and period II (June 1, 1995 to March 31, 1997). All of the regions 23 practicing surgeons responsible for these patients were surveyed to assess changes in practice patterns potentially related to bleeding risks. RESULTS The adjusted rates of reexploration for bleeding declined 46% between periods I and II (3.6% versus 2.0%, p < 0.001). All of the five cardiac centers in northern New England showed similar trends with adjusted risk reductions ranging from 32% to 48% between the two time periods. This decline occurred despite the patients in period II having higher percentages of risk factors for reexploration for bleeding compared to patients in period I. From the surgeon survey, the number of surgeons using antifibrinolytics markedly increased from period I to period II. More surgeons were also using preoperative aspirin and heparin up until the time of surgery in period II. CONCLUSIONS Similar to the rates of mortality, the rates of reexploration for bleeding following CABG surgery are substantially declining. This decrease in the reexploration rates occurred despite higher patient risks.

Predictors of 30-day hospital readmission after coronary artery bypass

BACKGROUND Risk factors for 30-day hospital readmission following coronary artery bypass grafting (CABG) have not been established. METHODS We prospectively followed 485 consecutive patients who underwent isolated primary CABG at our institution in 1997. Patients were contacted by telephone at 30 days following operation to determine readmission status. RESULTS The overall readmission rate was 16% (76 of 485). Female gender (25% versus 11%, p = 0.001) and diabetes (22% versus 12%, p = 0.005) were associated with significantly higher readmission rates. The relationship between female gender and readmission persisted after correcting for age and other comorbidities. Congestive heart failure trended towards a significant relationship with increased readmission rate (22% versus 14%, p = 0.09). There were no significant associations between 30-day readmission rate and age, hypertension, chronic obstructive pulmonary disease, history of myocardial infarction, peripheral vascular disease, creatinine level of > or = 1.4 mg/dL, or decreased left ventricular ejection fraction (< 40%). CONCLUSIONS These data show that most of the classic risk factors for postoperative mortality are not necessarily associated with increased readmission. However, female gender and diabetes are associated with greater than twice the risk of 30-day readmission following CABG.

Decreasing mortality for aortic and mitral valve surgery in northern New England

BACKGROUND Although numerous reports have documented declining mortality rates associated with coronary artery bypass surgery in recent years, it is unknown whether similar trends have occurred with valve surgery during this time. METHODS We conducted a regional, prospective study to assess trends in patient casemix and in-hospital mortality rates over time with aortic valve replacement (AVR), mitral valve replacement (MVR), and mitral valve repair. Data were collected from all patients undergoing AVR (n = 2,596), MVR (n = 759), or mitral valve repair (n = 522) in Northern New England between January 1992 and December 1997. Logistic regression was used to identify significant predictors of in-hospital mortality and to calculate risk-adjusted mortality rates. RESULTS For AVR, the trend in patient casemix was toward increased risk with increases in patient age and in the proportion of patients with: body surface area less than 1.7, diabetes, coronary artery disease, and prior valve surgery. A decrease was noted in the proportion of patients undergoing additional surgical procedures. For MVR, patient risk improved over the time period with fewer female patients and fewer patients with coronary artery disease. For mitral valve repair patient risk increased over the time period with increases in the proportion of patients with coronary artery disease, diabetes, and whose surgical priority was classified as urgent. In addition, there was a borderline significant increase in the proportion of mitral valve repair patients in New York Heart Association class IV preoperatively. Risk-adjusted mortality decreased 44% from 9.3% in 1992 through 1993 to 5.3% in 1996 through 1997 for patients undergoing AVR (p = 0.01) and decreased 53% from 13.6% in 1992 through 1993 to 8.2% in 1996 through 1997 for patients undergoing MVR (p = 0.01). We observed a statistically insignificant increase in risk-adjusted mortality over the time period for patients undergoing mitral valve repair (from 3.6% in 1992 through 1993 to 5.0% in 1996 through 1997; p = 0.34). CONCLUSIONS Significant improvement in mortality rates with valve replacement was observed in northern New England during this time period. This improvement persisted following adjustment for changes in patient casemix over this time. These trends mirror improvements in mortality with other cardiac surgical interventions that have been observed in recent years in our region and nationally.

The completely endoscopic treatment of atrial fibrillation: report on the first 14 patients with early results.

UNLABELLED We report the early results of a new completely endoscopic technique for the treatment of atrial fibrillation (AF). METHODS Fourteen patients underwent surgery solely for the treatment of AF. The thoracoscopic technique delivered microwave energy to the epicardial surface of the beating heart. Access was obtained through 3 right-sided and 3 left-sided thoracic ports. The AFx/Guidant Flex-10 catheter was employed to produce a box lesion around the pulmonary veins along with additional right- and left-sided lesions. The left atrial appendage was amputated. RESULTS Ten patients had paroxysmal fibrillation, 1 had persistent fibrillation, and 3 were in permanent AF. Mean age of the group was 60 years, and their mean duration of AF was 74 months. Half had undergone unsuccessful attempts at chemical and/or electrical cardioversion. There were no deaths. Two patients required conversion to open procedure to control bleeding from the left atrial appendage. Average procedure time was 221 minutes, with the last 2 procedures taking less than 2 hours. Median length of hospital stay was 6 days, with 7 patients staying less than 3 days. Seventy-one percent of patients were in sinus rhythm at discharge, 100% at 6 months follow-up, and 67% at 12 months. CONCLUSION Totally endoscopic microwave ablation of atrial fibrillation appears to be safe and truly minimally invasive. It is associated with a short length of stay, short procedure time, and acceptable rhythm results. This procedure has the potential to greatly expand the indications for surgery in patients suffering from AF and deserves longer-term investigation.