Joon Bum Kim

Total arch repair versus hemiarch repair in the management of acute DeBakey type I aortic dissection

OBJECTIVE In acute DeBakey type I aortic dissection, it is still controversial whether to perform extended aortic replacement to improve long-term outcome or to use a conservative strategy with ascending aortic and hemiarch replacement to palliate a life-threatening condition. METHODS Between 1999 and 2009, 188 consecutive patients (93 women; mean age, 57.4±11.7 years) with acute DeBakey type I aortic dissection underwent hemiarch (Hemiarch group; n=144) or total arch replacement (Total arch group; n=44) in conjunction with ascending aorta replacement. Clinical outcomes were compared after adjustment for baseline characteristics using inverse-probability-of-treatment weighting. RESULTS Median follow-up was 47.5 months (range 0-130.4 months) and was 92.0% (n=173) complete. Five-year unadjusted survival and permanent-neurologic-injury-free survival rates were 65.8±8.3% and 43.1±9.7% in the Total arch group, and 83.2±3.3% and 75.2±4.0% in the Hemiarch group, respectively (P=0.013 and <0.001). After adjustment, the Total arch group patients were at greater risks of death (hazard ratio (HR) 2.38, 95% confidence interval (CI) 1.21-4.67; P=0.012), and permanent neurologic injury (HR 3.25, 95% CI 1.31-8.04; P=0.011) compared to the Hemiarch group patients. The risks of the re-operation for aortic pathology or distal aortic dilatation (>55 mm) were similar for both groups (HR 0.33, 95% CI 0.08-1.43; P=0.14). CONCLUSIONS Total arch repair was associated with greater morbidity and mortality compared with hemiarch repair in acute DeBakey type I aortic dissection. Rates of aortic re-operation or aortic dilatation were not significantly different between the two surgical strategies. These findings support a conservative surgical approach to circumvent this life-threatening situation.

Mild-to-moderate functional tricuspid regurgitation in patients undergoing valve replacement for rheumatic mitral disease: the influence of tricuspid valve repair on clinical and echocardiographic outcomes

Background The decision to repair mild-to-moderate functional tricuspid regurgitation (TR) during left-side heart surgery remains controversial. Objectives To avoid heterogeneity in patient population, patients with TR undergoing isolated mechanical mitral valve (MV) replacement for rheumatic mitral diseases were evaluated. Methods Between 1997 and 2009, 236 patients with mild-to-moderate functional TR underwent first-time isolated mechanical MV replacement for rheumatic mitral diseases with (n=123; repair group) or without (n=113; non-repair group) tricuspid valve (TV) repair. Survival, valve-related complications, and TV function in these two groups were compared after adjustment for baseline characteristics using inverse-probability-of-treatment weighting. Results Follow-up was complete in 225 patients (95.3%) with a median follow-up of 48.7 months (IQR 20.2–89.5 months), during which time 991 echocardiographic assessments were done. Freedom from moderate-to-severe TR at 5 years was 92.9±2.9% in the repair group and 60.8±6.9% in the non-repair group (p<0.001 and 0.048 in crude and adjusted analyses, respectively). After adjustment, both groups had similar risks of death (HR=0.57, p=0.43), tricuspid reoperation (HR=0.10, p=0.080) and congestive heart failure (HR=1.12, p=0.87). Postoperative moderate-to-severe TR was an independent predictor of poorer event-free survival (HR=2.90, p=0.038). Conclusions These findings support the strategy of correcting mild-to-moderate functional TR at the time of MV replacement to maintain TV function and improve clinical outcomes.

Long-Term Survival Following Coronary Artery Bypass Grafting : Off-Pump Versus On-Pump Strategies

OBJECTIVES This study sought to compare long-term survival after off- and on-pump coronary artery bypass grafting (CABG). BACKGROUND Although several large-scale clinical trials have compared the surgical outcomes between off- and on-pump CABG, the long-term survival has not been compared between the 2 surgical strategies in a reasonably sized cohort. METHODS We evaluated long-term survival data in 5,203 patients (age 62.9 ± 9.1 years, 1,340 females) who underwent elective isolated CABG (off-pump: n = 2,333; on-pump: n = 2,870) from 1989 through 2012. Vital statuses were validated using the Korean National Registry of Vital Statistics. Long-term survival was compared with the use of propensity scores and inverse probability weighting to adjust selection bias. RESULTS Patients undergoing on-pump CABG had a higher number of distal anastomoses than those undergoing off-pump CABG (3.7 ± 1.2 vs. 3.0 ± 1.1; p < 0.001). Survival data were complete in 5,167 patients (99.3%), with a median follow-up duration of 6.4 years (interquartile range: 3.7 to 10.5 years; maximum 23.1 years). During follow-up, 1,181 patients (22.7%) died. After adjustment, both groups of patients showed a similar risk of death at 30 days (odds ratio: 0.70; 95% confidence interval [CI]: 0.35 to 1.40; p = 0.31) and up to 1 year (hazard ratio [HR]: 1.11; 95% CI: 0.74 to 1.65; p = 0.62). For overall mortality, however, patients undergoing off-pump CABG were at a significantly higher risk of death (HR: 1.43; 95% CI: 1.19 to 1.71; p < 0.0001) compared with those undergoing on-pump CABG. In subgroup analyses, on-pump CABG conferred survival benefits in most demographic, clinical, and anatomic subgroups compared with off-pump CABG. CONCLUSIONS In patients undergoing elective isolated CABG, on-pump strategy conferred a long-term survival advantage compared with off-pump strategy.

Left Atrial Ablation Versus Biatrial Ablation in the Surgical Treatment of Atrial Fibrillation

BACKGROUND The purpose of this study was to compare the clinical and rhythm outcomes between left atrial ablation and biatrial ablation in patients with atrial fibrillation-associated mitral valve diseases. METHODS Data were collected on 284 patients who underwent left atrial ablation (n = 85) or biatrial ablation (n = 199) of atrial fibrillation using a cryoablation system combined with mitral operation from 2006 through 2009. Outcomes were compared using a propensity score study design based on 20 baseline patient characteristics. RESULTS In baseline characteristics, patients in the biatrial group were more likely to have higher risk clinical and echocardiographic profiles than patients in the left atrial group. There were 2 early deaths (0.7%), 1 in each group, and 5 cases of permanent pacemaker implantation (1.8%) only in the biatrial group. Follow-up was complete in 95.1% (n = 270). During a mean follow-up duration of 26.0 ± 13.3 months, there were 12 late deaths (1 in the left atrial group, 11 in the biatrial group). Cumulative incidence of atrial fibrillation in the absence of antiarrhythmic medications at 2 years was 25.9% ± 5.8% in the left atrial group and 14.3% ± 2.8% in the biatrial group (adjusted hazard ratio 3.06, 95% confidence interval: 1.41 to 6.66, p = 0.005). Major adverse events included stroke in 1, cardiac reoperation in 3, and anticoagulation-related hemorrhages in 16, infective endocarditis in 1, and mechanical valve thrombosis in 1, with no significant intergroup differences in major event-free survival rate (p = 0.73). CONCLUSIONS Compared with left atrial ablation, biatrial ablation was more effective in restoration and maintenance of sinus rhythm without increasing the risk of postoperative complications.

Clinical and echocardiographic outcomes after surgery for severe isolated tricuspid regurgitation

OBJECTIVE Few studies have investigated the outcomes after surgical correction of severe isolated tricuspid regurgitation. METHODS The medical records of 51 consecutive patients (aged 55.8 ± 12.9 years, 25 male) who underwent tricuspid valve surgery at the Asan Medical Center between September 1996 and July 2010 were evaluated retrospectively. All patients had severe isolated tricuspid regurgitation but no significant left-sided cardiac disease or history of heart surgery. RESULTS Tricuspid valve repair (n = 37, 72.5%) or replacement (n = 14, 27.5%) was performed. Replacement involved mechanical (n = 4) or bioprosthetic valves (n = 10). One early death occurred (2.0%). During a median follow-up period of 47.4 months (interquartile range, 10.4-61.4 months), 9 late deaths, 3 readmissions for congestive heart failure, 2 heart transplantations, and 1 tricuspid valve reoperation occurred. Overall and event-free survivals at 5 years were 83.5% ± 5.4% and 77.3% ± 6.1%, respectively. In the multivariable Cox regression analysis, preoperative hemoglobin (P = .045), serum bilirubin (P = .008), estimated glomerular filtration rate (P = .045), and systolic right ventricular dimension (P = .047) were significant and independent determinants of clinical outcome. On serial echocardiographic evaluations (median follow-up period, 28.5 months; interquartile range, 18.9-68.7 months), moderate-to-severe tricuspid regurgitation was detected in 21 patients (41%). Severe tricuspid regurgitation after tricuspid valve repair or bioprosthetic valve replacement was a significant predictor of poor event-free survival, even after adjustment for preoperative risk factors (P = .036). CONCLUSIONS In the present cohort, preoperative anemia, renal/hepatic dysfunction, right ventricular dilatation, and significant postoperative tricuspid regurgitation were associated with poor outcomes. Timely surgery is advisable in patients with severe isolated tricuspid regurgitation before the development of anemia, organ dysfunction, or right ventricular dilatation.

Long-term outcomes after surgery for rheumatic mitral valve disease: valve repair versus mechanical valve replacement.

OBJECTIVES Although mitral valve (MV) repair is known to be superior to replacement in overall clinical outcomes, the appropriateness of valve repair for rheumatic MV disease remains controversial because of the risks of recurrent mitral dysfunction and the need for re-operation. METHODS From 1997 to 2007, 540 patients underwent either isolated MV repair (n=122) or replacement with a mechanical prosthesis (n=418) in treatment of rheumatic MV disease. Survival and morbidity were evaluated using Kaplan-Meier analysis and Cox regression, including propensity score analysis. RESULTS Follow-up was complete in 96.1% of patients (mean, 71.8+/-39.1 months). Patients undergoing repair were younger; more likely to have predominant mitral regurgitation; and less likely to show atrial fibrillation (AF), significant tricuspid regurgitation or pulmonary hypertension, than those undergoing replacement. The 10-year freedom from cardiac death rate was 92.0+/-4.2% following repair and 86.8+/-2.3% following replacement (P=0.042). After adjustment for baseline differences, repair and replacement were found to be similar in terms of cardiac survival (P=0.25), re-operation (P=0.68) and thrombo-embolic complication (P=0.20) rates. Replacement patients had more anticoagulation therapy-related complications (P=0.030). Independent factors positively associated with combined cardiac death and major morbidities included older patient age (P=0.010), uncorrected AF (P=0.015) and the presence of significant tricuspid regurgitation (P=0.012) or coronary disease (P=0.043). The influence of the type of MV surgery was statistically marginal (P=0.093). CONCLUSIONS When performed for selected patients, MV repair had excellent durability comparable to mechanical valve replacement in rheumatic disease. Both MV repair and replacement had comparable long-term clinical results; therefore, repair surgery seems to be more beneficial by avoiding troublesome life-long anticoagulation and risks of bleeding.

Determinants of half-site spacing preferences that distinguish AP-1 and ATF/CREB bZIP domains

The AP-1 and ATF/CREB families of eukaryotic transcription factors are dimeric DNA-binding proteins that contain the bZIP structural motif. The AP-1 and ATF/CREB proteins are structurally related and recognize identical half-sites (TGAC), but they differ in their requirements for half-site spacing. AP-1 proteins such as yeast GCN4 preferentially bind to sequences with overlapping half-sites, whereas ATF/CREB proteins bind exclusively to sequences with adjacent half-sites. Here we investigate the distinctions between AP-1 and ATF/CREB proteins by determining the DNA-binding properties of mutant and hybrid proteins. First, analysis of GCN4-ATF1 hybrid proteins indicates that a short surface spanning the basic and fork regions of the bZIP domain is the major determinant of half-site spacing. Replacement of two GCN4 residues on this surface (Ala244 and Leu247) by their ATF1 counterparts largely converts GCN4 into a protein with ATF/CREB specificity. Secondly, analysis of a Fos derivative containing the GCN4 leucine zipper indicates that Fos represents a novel intermediate between AP-1 and ATF/CREB proteins. Thirdly, we examine the effects of mutations in the invariant arginine residue of GCN4 (Arg243) that contacts the central base pair(s) of the target sites. While most mutations abolish DNA binding, substitution of a histidine residue results in a GCN4 derivative with ATF/CREB binding specificity. These results suggest that the AP-1 and ATF/CREB proteins differ in positioning a short surface that includes the invariant arginine and that AP-1 proteins may represent a subclass (and perhaps evolutionary offshoot) of ATF/CREB proteins that can tolerate overlapping half-sites.

Long-term outcome of modified maze procedure combined with mitral valve surgery: Analysis of outcomes according to type of mitral valve surgery

OBJECTIVE Efficacy of the maze procedure for atrial fibrillation associated with advanced mitral disease not amenable to repair has not been determined. This study investigated whether type of mitral surgery affects maze outcome. METHODS From January 1999 to January 2007, a total of 435 patients underwent the maze procedure and concomitant mitral operation. Of these, 226 underwent mitral repair and 209 underwent mitral replacement. RESULTS Median follow-up was 40.6 months (0.4-111.3 months), with 25 deaths and 6 strokes. Nineteen patients did not regain normal sinus rhythm. There were no significant intergroup differences in survival, stroke incidence, or sinus rhythm restoration rate. Among 427 early survivors, 64 had late atrial fibrillation recurrence. Five-year atrial fibrillation-free rates were 80.9% + or - 3.7% in the repair group and 77.3% + or - 4.1% in the replacement group (P = .099). By multivariate analysis, age at surgery older than 60 years (P = .045), fine atrial fibrillation wave pattern (P = .033), and preoperative left atrial dimension greater than 60 mm (P = .019) were independent risk factors for atrial fibrillation recurrence, whereas type of mitral surgery was not (P = .573). Although transmitral A-wave prevalence did not differ significantly between groups beyond the early postoperative period, A-wave velocity was faster in the repair group through the entire postoperative period (P < .001). CONCLUSIONS Maze outcomes were acceptable regardless of type of mitral surgery. Late atrial fibrillation recurrence was mainly affected by age, unfavorable electrocardiographic characteristics of atrial fibrillation, and larger preoperative left atrial size.

Long-Term Outcomes of Mechanical Valve Replacement in Patients with Atrial Fibrillation: Impact of the Maze Procedure

Background— The long-term benefits of the maze procedure in patients with chronic atrial fibrillation undergoing mechanical valve replacement who already require lifelong anticoagulation remain unclear. Methods and Results— We evaluated adverse outcomes (death; thromboembolic events; composite of death, heart failure, or valve-related complications) in 569 patients with atrial fibrillation–associated valvular heart disease who underwent mechanical valve replacement with (n=317) or without (n=252) a concomitant maze procedure between 1999 and 2010. After adjustment for differences in baseline risk profiles, patients who had undergone the maze procedure were at similar risks of death (hazard ratio, 1.15; 95% confidence interval, 0.65–2.03; P=0.63) and the composite outcomes (hazard ratio, 0.82; 95% confidence interval, 0.50–1.34; P=0.42) but a significantly lower risk of thromboembolic events (hazard ratio, 0.29; 95% confidence interval, 0.12–0.73; P=0.008) compared with those who underwent valve replacement alone at a median follow-up of 63.6 months (range, 0.2–149.9 months). The effect of superior event-free survival by the concomitant maze procedure was notable in a low-risk EuroSCORE (0–3) subgroup (P=0.049), but it was insignificant in a high-risk EuroSCORE (≥4) subgroup (P=0.65). Furthermore, the combination of the maze procedure resulted in superior left ventricular (P<0.001) and tricuspid valvular functions (P<0.001) compared with valve replacement alone on echocardiographic assessments performed at a median of 52.7 months (range, 6.0–146.8 months) after surgery. Conclusion— Compared with valve replacement alone, the addition of the maze procedure was associated with a reduction in thromboembolic complications and improvements in hemodynamic performance in patients undergoing mechanical valve replacement, particularly in those with low risk of surgery.

Risk of rupture or dissection in descending thoracic aortic aneurysm.

Background— Current practice guidelines recommend surgical repair of large thoracic aortic aneurysms to prevent fatal aortic dissection or rupture, but limited natural history data exist to support clinical criteria for timely intervention. Methods and Results— Of 3247 patients with thoracic aortic aneurysm registered in our institutional Thoracic Aortic Center Database, we identified and reviewed 257 nonsyndromic patients (age, 72.4±10.5 years; 143 female) with descending thoracic or thoracoabdominal aortic aneurysm without a history of aortic dissection in whom surgical intervention was not undertaken. The primary end point was a composite of aortic dissection/rupture and sudden death. Baseline mean maximal aortic diameter was 52.4±10.8 mm, with 103 patients having diameters ≥55 mm. During a median follow-up of 25.1 months (quartiles 1–3, 8.3–56.4 months), definite and possible aortic events occurred in 19 (7.4%) and 31 (12.1%) patients, respectively. On multivariable analyses, maximal aortic diameter at baseline emerged as the only significant predictor of aortic events (hazard ratio=1.12; 95% confidence interval, 1.08–1.15). Estimated rates of definite aortic events within 1 year were 5.5%, 7.2%, and 9.3% for aortic diameters of 50, 55, and 60 mm, respectively. Receiver-operating characteristic curves for discriminating aortic events were higher for indexed aortic sizes referenced by body size (area under the curve=0.832–0.889) but not significantly different from absolute maximal aortic diameter (area under the curve=0.805). Conclusions— Aortic size was the principal factor related to aortic events in unrepaired descending thoracic or thoracoabdominal aortic aneurysm. Although the risk of aortic events started to increase with a diameter >5.0 to 5.5 cm, it is uncertain whether repair of thoracic aortic aneurysms in this range leads to overall benefit, and the threshold for repair requires further evaluation.