Robert F. Hebeler

New-Onset Postoperative Atrial Fibrillation After Isolated Coronary Artery Bypass Graft Surgery and Long-Term Survival

Background—The advancing age and generally increasing risk profile of patients receiving isolated coronary artery bypass graft (CABG) surgery is expected to raise incidence of new-onset postoperative atrial fibrillation (AFIB) resulting in potentially higher risk of adverse outcomes. In the early postoperative course, new-onset post-CABG AFIB is considered relatively easy to treat and is believed to have little impact on patients’ long-term outcome. However, little has been done to determine the effect of new-onset post-CABG AFIB on long-term survival, and this relationship is unclear. Methods and Results—Survival was assessed in a cohort of 6899 consecutive patients without preoperative AFIB who underwent isolated CABG at Baylor University Medical Center, Dallas, Tex, between January 1, 1997 and December 31, 2006; patients who died during CABG were excluded. Ten-year unadjusted survival was 52.3% (48.4%, 56.0%) for patients with new-onset postoperative AFIB and 69.4% (67.3%, 71.4%) for patients without it. A propensity-adjusted model controlling for risk factors identified by the Society of Thoracic Surgeons and other clinical/nonclinical details was used to investigate the association between new-onset AFIB post-CABG and long-term survival. After adjustment, new-onset AFIB post-CABG was significantly associated (hazard ratio, 1.29; 95% CI, 1.16, 1.45) with increased risk of death. Conclusions—This study provides evidence that new-onset post-CABG AFIB is significantly associated with increased long-term risk of mortality independent of patient preoperative severity. After controlling for a comprehensive array of risk factors associated with post-CABG adverse outcomes, risk of long-term mortality in patients that developed new-onset post-CABG AFIB was 29% higher than in patients without it.

Comparison of the Structure of the Aortic Valve and Ascending Aorta in Adults Having Aortic Valve Replacement for Aortic Stenosis Versus for Pure Aortic Regurgitation and Resection of the Ascending Aorta for Aneurysm

Background— There is debate concerning whether an aneurysmal ascending aorta should be replaced when associated with a dysfunctioning aortic valve that is to be replaced. To examine this issue, we divided the patients by type of aortic valve dysfunction—either aortic stenosis (AS) or pure aortic regurgitation (AR)—something not previously undertaken. Methods and Results— Of 122 patients with ascending aortic aneurysm (unassociated with aortitis or acute dissection), the aortic valve was congenitally malformed (unicuspid or bicuspid) in 58 (98%) of the 59 AS patients, and in 38 (60%) of the 63 pure AR patients. Ascending aortic medial elastic fiber loss (EFL) (graded 0 to 4+) was zero or 1+ in 53 (90%) of the AS patients, in 20 (53%) of the 38 AR patients with bicuspid valves, and in all 12 AR patients with tricuspid valves unassociated with the Marfan syndrome. An unadjusted analysis showed that, among the 96 patients with congenitally malformed valves, the 38 AR patients had a significantly higher likelihood of 2+ to 4+ EFL than the 58 AS patients (crude odds ratio: 8.78; 95% confidence interval: 2.95, 28.13). Conclusions— These data strongly suggest that the type of aortic valve dysfunction—AS versus pure AR—is very helpful in predicting loss of aortic medial elastic fibers in patients with ascending aortic aneurysms and aortic valve disease.

Comparison of Age, Gender, Number of Aortic Valve Cusps, Concomitant Coronary Artery Bypass Grafting, and Magnitude of Left Ventricular-Systemic Arterial Peak Systolic Gradient in Adults Having Aortic Valve Replacement for Isolated Aortic Valve Stenosis

Correlation of the structure of the operatively excised aortic valve with various clinical variables has received relatively little attention. This report describes certain observations in 115 patients aged >30 years (mean age 70) who had aortic valve replacement for aortic valve stenosis unassociated with mitral valve dysfunction. The operatively excised aortic valve was congenitally unicuspid in 3 patients (3%), congenitally bicuspid in 54 patients (47%), tricuspid in 57 patients (50%), and of uncertain structure in 1. Of the 87 patients (76%) aged > or =65 years (Medicare population), 36 (41%) had congenitally malformed valves (bicuspid in each), and of the 28 patients (24%) aged <65 years, 21 (75%) had congenitally malformed valves. A higher percentage of patients with congenitally malformed valves had peak systolic pressure gradients across the valve >50 mm Hg than did patients with tricuspid valves (57% vs 43%). Concomitant coronary artery bypass grafting (CABG) was performed in 52 patients (45%) (34 men and 18 women), and they had average peak systolic pressure gradients across the valve significantly lower than patients without coronary bypass (46 vs 64 mm Hg): 39% of the 57 patients with congenitally malformed valves and 53% of the 57 patients with tricuspid valves had concomitant coronary bypass (insignificant difference). Thus, in a relatively older population of 115 patients having aortic valve replacement for isolated aortic valve stenosis, with or without associated aortic regurgitation, one half had congenitally malformed valves (either unicuspid or bicuspid valves) and one half had tricuspid valves. Patients having concomitant CABG had significantly smaller gradients across the stenotic valves than those who had no CABG.

Valve Structure and Survival in Quadragenarians Having Aortic Valve Replacement for Aortic Stenosis (±Aortic Regurgitation) With Versus Without Coronary Artery Bypass Grafting at a Single US Medical Center (1993 to 2005)

The purpose of this study was to determine the effect of simultaneous coronary artery bypass grafting (CABG) and the influence of valve structure on both early and late survival in quadragenarians having aortic valve replacement (AVR) for aortic stenosis (AS) (with or without aortic regurgitation). We analyzed survival and valve structure in 48 adults (12 women), aged 40 to 49 years, having AVR for AS from 1993 through 2005 at Baylor University Medical Center, including 7 (15%) with and 41 (85%) without simultaneous CABG. Of the 48 quadragenarians, none died within 60 days of operation. Assessment of the relation between long-term survival and gender, aortic valve structure, preoperative severity of the AS, and concomitant CABG was not possible due to the low mortality. Four patients (9%) died >60 days after AVR: at 1.8, 6.3, 7.1, and 9.9 years, respectively. The aortic valve was congenitally unicuspid in 15 patients (31%), congenitally bicuspid in 32 (67%), and 3-cuspid in 1 (2%). In conclusion, of the 48 quadragenarians having AVR for AS, 47 (98%) had a congenitally malformed aortic valve, 60-day mortality was zero, and late mortality was low (8%).

Effect Of Body Mass Index On Survival In Patients Having Aortic Valve Replacement For Aortic Stenosis With Or Without Concomitant Coronary Artery Bypass Grafting

The purpose of this report is to describe the effect of body mass index (BMI) on 30-day and late outcome in patients having aortic valve replacement (AVR) for aortic stenosis (AS) with or without concomitant coronary artery bypass grafting. From January 2002 through June 2010 (8.5 years), 1,040 operatively excised stenotic aortic valves were submitted to the cardiovascular laboratory at Baylor University Medical Center at Dallas. Of the 1,040 cases 175 were eliminated because they had a previous cardiac operation. The present study included 865 adults whose AVR for AS was their first cardiac operation. Propensity-adjusted analysis showed that 30-day and late mortality were strongly and significantly associated with BMI. Decreased risk of 30-day and long-term mortality was observed for patients with BMI in the low 30s compared to patients with BMI in the mid 20s or >40 kg/m(2). In conclusion, the findings in this study indicate a strong and significant adjusted association between BMI and 30-day and long-term mortality in patients having AVR for AS with or without concomitant coronary artery bypass grafting. Better survival was observed in patients with BMIs in the low 30s compared to patients with BMIs in the mid 20s and >40 kg/m(2).

Comparing long-term survival between patients undergoing off-pump and on-pump coronary artery bypass graft operations.

BACKGROUND As the population of the United States and Western Europe ages, the number of patients undergoing isolated coronary artery bypass grafting (CABG) for revascularization can be expected to increase. This study investigated long-term survival in patients undergoing off-pump vs on-pump CABG. METHODS Survival was assessed in 8081 consecutive patients who underwent isolated CABG (732 received off-pump) between January 1, 1997, and December 31, 2008. A propensity-adjusted model controlling for preoperative risk factors identified by the Society of Thoracic Surgeons and other preoperative clinical and nonclinical details was used to assess adjusted long-term mortality differences between off-pump and on-pump CABG. RESULTS Ten-year unadjusted survival was 54.7% (95% confidence interval, 47.2% to 61.6%) in off-pump CABG patients and 62.3% (95% confidence interval 60.9% to 63.8%) in on-pump CABG patients. The log-rank test (p=0.012) indicated a significantly higher risk of death in off-pump CABG patients. After adjustment, the risk of death remained significantly higher in the off-pump CABG patients (hazard ratio, 1.18; 95% confidence interval, 1.02 to 1.38). The adjusted association regarding off-pump learning curve and survival was assessed separately and was not statistically significant (p=0.774), further validating our findings regarding off-pump CABG. CONCLUSIONS After controlling for preoperative severity of disease and other possible confounders, the risk of long-term mortality in patients undergoing off-pump CABG is significantly higher than in those undergoing on-pump CABG. For multivessel coronary disease, on-pump CABG might be preferable to off-pump CABG given that it may achieve a more complete and durable revascularization.

Mechanism and Severity of Mitral Regurgitation by Transesophageal Echocardiography in Patients Referred for Percutaneous Valve Repair

Percutaneous mitral valve repair with the MitraClip has been shown to decrease mitral regurgitation (MR) severity, left ventricular volumes, and functional class in patients with severe (3+ or 4+) MR. Determination of which patients are optimal candidates for MitraClip therapy versus surgery has not been rigorously evaluated. Transesophageal echocardiography was prospectively performed in 113 consecutive patients referred for potential MitraClip therapy under the REALISM continued access registry. MR severity was assessed quantitatively in all patients. Mitral valve anatomy and feasibility of MitraClip placement were assessed by transesophageal echocardiography and clinical parameters. MR was degenerative (mitral valve prolapse) in 60 patients (53%), functional (anatomically normal) in 44 (39%), and thickened with restricted motion (Carpentier IIIB classification) in 9 (8%). MR was mild in 19 patients (17%), moderate in 27 (24%), and severe (3 to 4+) in 67 (59%) by Transesophageal echocardiography. MitraClip placement was performed in only 17 of 113 patients (15%); all were successful. Surgical mitral valve repair was performed in 25 patients (22%), mitral valve replacement in 12 (11%). Most patients (59 of 113, 52%) were treated medically, usually because MR was not severe enough to warrant intervention. In conclusion, most patients referred for MitraClip therapy do not have severe enough MR to warrant intervention. Of those with clinical need for intervention, surgery is more often recommended for anatomic or clinical reasons. Three-dimensional transesophageal echocardiography with quantitative assessment of MR severity is helpful in evaluating these patients.

Prospective analysis of endoscopic vein harvesting

BACKGROUND Utilization of bridging vein harvesting (BVH) of saphenous vein grafts (SVG) for coronary artery bypass grafting (CABG) results in large wounds with great potential for pain and infection. Endoscopic vein harvesting (EVH) may significantly reduce the morbidity associated with SVG harvesting. METHODS A prospective database of 200 matched patients receiving EVH and BVH was compared. The patients all underwent CABG done over a period of 4 months (April to August 2000). Patients were excluded if they had prior vein harvesting. RESULTS The EVH and BVH group included 100 patients each with similar demographics. The patients in the EVH group had significantly fewer wound complications, mean days to ambulation, and total length of stay (P <0.05). There was no difference in harvest time or vein injuries. CONCLUSION Endoscopic vein harvesting results in significantly fewer wound complications, decrease in days to ambulation, and the total length of stay. EVH is superior to BVH in patients undergoing CABG.

Relation of Obesity to Atrial Fibrillation After Isolated Coronary Artery Bypass Grafting

The impact of obesity on risk of atrial fibrillation (AF) after coronary artery bypass grafting (CABG) is poorly understood. This study was performed to investigate the relation between body mass index (BMI; kilograms per square meter) or body surface area (BSA; square meters) and AF after CABG. Postoperative AF was assessed in a cohort of 7,027 consecutive patients without preoperative AF undergoing isolated CABG at Baylor University Medical Center from January 1, 1997 to December 31, 2006. Two propensity-adjusted models controlling for risk factors identified by the Society of Thoracic Surgeons and other clinical/nonclinical details were used. After adjustment, BMI and BSA (modeled using smoothing techniques to avoid categorization) were strongly associated (p <0.0001) with postoperative AF. Although evidence existed that gender was associated with AF (p <0.0001 and p = 0.1088 for BSA and BMI models, respectively), there was no indication that the effect of BMI or BSA on postoperative AF varied by gender. In conclusion, this study demonstrates that increased BMI and BSA are associated with a higher risk of AF after CABG and that risk for men is higher for the entire BSA spectrum and for extreme values of BMI.

Initial experience in the treatment of thoracic aortic aneurysmal disease with a thoracic aortic endograft at Baylor University Medical Center.

A retrospective review of 27 patients who underwent endovascular repair of thoracic aneurysms and of other thoracic aortic pathology with the thoracic aortic endograft (Gore Medical, Flagstaff, AZ) from June 2005 to July 2007 was performed. The mean follow-up period was 13.5 months (range, 2–25 months). Indications for thoracic endografting included descending thoracic aneurysms (n = 18), thoracoabdominal aneurysms (n = 3), traumatic aortic injuries (n = 3), penetrating aortic ulcers (n = 2), and contained rupture of a type B dissection (n = 1). One patient died during the procedure, for an overall mortality rate of 3.7%. The average length of stay was 8.1 days, with an average stay in the intensive care unit of 4.2 days. If patients with traumatic aortic injuries were excluded, the average overall and intensive care unit length of stay were 5.6 and 1.8 days, respectively. There was one incident of spinal cord ischemia (3.7%). There were five type I or type III endoleaks, three of which required revision (11.1%). In conclusion, thoracic endografting is a safe and viable option for the repair of descending thoracic aneurysms and other aortic pathologies. We have found it to be less invasive, even in conjunction with preoperative debranching procedures, with a shorter recovery time, decreased perioperative morbidity and blood loss, and decreased perioperative mortality compared with standard open repair.