Mariano E. Brizzio

Propensity matched analysis of bilateral internal mammary artery versus single left internal mammary artery grafting at 17-year follow-up: validation of a contemporary surgical experience.

OBJECTIVES Bilateral internal mammary arteries (BIMA) remains widely underutilized in coronary artery bypass grafting (CABG). Although prior research has demonstrated a long-term benefit of the use of BIMA over left internal mammary artery (LIMA)-only, validation of these results is lacking in a contemporary surgical experience. We compared complications and survival at 17-year follow-up in a large series of consecutive CABG patients from a single institution that underwent BIMA grafting with a propensity-matched group where LIMA only was used. METHODS Propensity scores representing the estimated probabilities of patients receiving either BIMA or LIMA alone were developed based on 22 observed baseline covariates in a logistic regression model with procedure group as the dependent variable. The nearest-neighbour-matching algorithm with Greedy 5-1 Digit Matching was used to produce two patient cohorts of 928 patients each balanced for baseline factors. We compared 30-day morbidity and mortality, as well as long-term survival at 5-year intervals up to 17-year follow-up. RESULTS In-hospital and 30-day mortality was 0.8% for the BIMA group and 1.1% for the LIMA-saphenous vein grafting (SVG). No significant difference was found in complications, mortality and/or length-of-stay between these two groups. Off-pump was done in 48.9% of BIMA cases and 51.3% of LIMA cases. Regardless of the types of grafts used, on-pump patients were more likely to have postoperative permanent strokes and longer postoperative lengths of stay. Use of the BIMA over LIMA-only had a statistically significant impact conferring a 10% survival advantage at 10-year and 18% at 15-year follow-up. The Kaplan-Meier survival curves comparing off-/on-pump BIMA and off-/on-pump LIMA-SVG patients demonstrated a 22% survival advantage for off-pump BIMA patients when compared with on-pump LIMA-SVG patients at 15-year follow-up. CONCLUSIONS Perioperative complications do not increase with the use of BIMAs. Long-term survival is optimized with off-pump CABG and BIMA grafting. The low morbidity and mortality rates in this series are likely due to the continuous evolution of technology and the adoption of less invasive options for CABG patients. A more widespread use of BIMAs in CABG patients would continue to improve the overall excellent short- and long-term results of this operation.

Stroke-Related Mortality in Coronary Surgery Is Reduced by the Off-Pump Approach

BACKGROUND Stroke remains an important complication after coronary artery bypass graft surgery (CABG). We sought to determine the frequency and death-related incidence of stroke after on-pump and off-pump CABG. METHODS We analyzed 4,869 consecutive isolated CABG performed in our institution. Of these, 3,490 (71.7%) were off-pump and 1,379 (28.3%) were on-pump. Propensity matched samples of 1,379 off-pump and 1,379 on-pump were compared on clinical presentation and The Society of Thoracic Surgeons (STS) predicted scores for risk of postoperative mortality and stroke. Univariate analyses were used to compare the relationship of off-pump and on-pump groups to postoperative mortality and stroke. Multivariate logistic regression was used to determine the unique association between all variables and occurrence of mortality after stroke. RESULTS No differences were found for sex, diabetes mellitus, history of renal failure, prior stroke, or timing of surgery. Postoperative mortality occurred in 75 patients (2.7%) and stroke in 47 (1.7%). The off-pump patients had a lower rate of stroke (1.0% versus 2.4%; p < 0.01) compared with on-pump patients. Mortality after stroke occurred in 14 patients, with a lower rate occurring in the off-pump group (14.3% versus 36.4%; p = 0.07). Multivariate analyses controlling for the effect of preoperative risk factors and STS mortality risk demonstrated that off-pump status was independently associated with an 84% decrease in the risk of death after stroke (adjusted odds ratio 0.157, 95% confidence interval: 0.035 to 0.711, p = 0.016). CONCLUSIONS Off-pump CABG is associated with lower stroke rates and stroke-related mortality. It may be useful to consider off-pump CABG for patients who are at higher risk for postoperative stroke.

The effects of using a radial artery in patients already receiving bilateral internal mammary arteries during coronary bypass grafting: 30-day outcomes and 14-year survival in a propensity-matched cohort

OBJECTIVES Recent studies have demonstrated the superiority of bilateral internal mammary arteries (BIMAs) as conduit material for coronary artery bypass grafting (CABG) surgery. However, there is limited research on the effects of other graft conduits used in patients who require additional bypasses. The goal of this study was to evaluate the impact of the radial artery (RA) when used in conjunction with the BIMAs. METHODS From the beginning of 2000 to the end of 2013, 4370 patients underwent CABG for three or more vessels at our institution. There were 568 and 183 patients who received BIMA + saphenous vein graft (SVG) and BIMA + radial ± SVG, respectively. Propensity matching was used to create a balanced cohort from these patients, which resulted in two groups of 183 patients. Thirty-day outcomes and long-term survival were compared between the two groups. Long-term follow-up was generated using the Social Security Death Index. RESULTS There were no significant differences in preoperative characteristics. For 30-day outcomes, the BIMA + radial ± SVG group had more postoperative atrial fibrillation (24.6 vs 12.0%; P = 0.001) and a longer median postoperative length of stay (6 vs 5 days; interquartile range = 2; P = 0.016) than BIMA + SVG patients. There was no significant difference in long-term survival between the two groups over the 14-year period. However, before year 10, the BIMA + SVG group had a trend towards higher survival, whereas on follow-up after 10 years, there was a trend that favoured the BIMA + radial ± SVG patients. Cox regression analysis using a time-dependent covariate demonstrated that when the groups were split at 10 years, there was a statistically significant improvement in survival of the BIMA + radial ± SVG group [adjusted hazard ratio 0.254 95% confidence interval (CI) 0.062-0.977; P = 0.048] over BIMA + SVG patients between 10 and 14 years. CONCLUSIONS Overall, there were no statistically significant differences in survival between the BIMA + SVG and BIMA + radial ± SVG groups over the 14 years. However, further analysis demonstrated that while the BIMA + radial ± SVG group had a trend towards decreased survival before 10 years, use of the RA in conjunction with BIMAs was associated with significantly increased survival in the later years. A larger cohort of patients with longer follow-up is needed to assess the outcomes of CABG using BIMA + radial ± SVG.

Blood transfusion in cardiac surgery does increase the risk of 5‐year mortality: results from a contemporary series of 1714 propensity‐matched patients

Studies have found that cardiac surgery patients receiving blood transfusions are at risk for increased mortality during the first year after surgery, but risk appears to decrease after the first year. This study compared 5‐year mortality in a propensity‐matched cohort of cardiac surgery patients.

Balancing the benefits and risks of blood transfusions in patients undergoing cardiac surgery: a propensity-matched analysis

OBJECTIVES Prior studies have found that cardiac surgery patients receiving blood transfusions are at risk for increased mortality and morbidity following surgery. It is not clear whether this increased risk occurs across all haematocrit (HCT) levels. The goal of this study was to compare operative mortality in propensity-matched cardiac surgery patients based on stratification of the preoperative HCT levels. METHODS Between 1 August 2004 and 30 June 2011, 3516 patients had cardiac surgery. One thousand nine hundred and twenty-two (54.5%) required blood transfusion during or after surgery. A propensity score for transfusion was developed based on 22 baseline variables. One thousand seven hundred and fourteen patients were matched: 857 in the transfusion group (TG) and 857 in the non-transfused control group (CG). Univariate analyses demonstrated that, after propensity matching, the groups did not differ on any baseline factors included in the propensity model. Operative mortality was defined as death within 30 days of surgery. Preoperative HCT was stratified into four groups: <36, 36-39, 40-42 and ≥ 43. RESULTS For HCT <36%, 30-day mortality was higher in the TG than that in the CG (3.0 vs 0.0%). For HCT 36-39, operative mortality was similar between TG (1.1%, N = 180) and CG (0.8%, N = 361; P = 0.748). For HCT 40-42, operative mortality was significantly higher in the TG compared with that in the CG (1.9 vs 0%, N = 108 and 218, respectively; P = 0.044). For HCT of ≥ 43, there was a trend towards higher operative mortality in the TG vs the CG (2.0 vs 0%, N = 102 and 152, respectively; P = 0.083). Other surgical complications followed the same pattern with higher rates found in the transfused group at higher presurgery HCT levels. HCT at discharge for the eight groups were similar, with an average of 29.1 ± 1.1% (P = 0.117). CONCLUSIONS Our study indicates that a broad application of blood products shows no discernible benefits. Furthermore, patients who receive blood at all HCT levels may be placed at an increased risk of operative mortality and/or other surgical complications. Paradoxically, even though patients with low HCTs theoretically should benefit the most, transfusion was still associated with a higher complication and mortality rate in these patients. Our results indicate that blood transfusion should be used judiciously in cardiac surgery patients.

Impact of pump status and conduit choice in coronary artery bypass: A 15-year follow-up study in 1412 propensity-matched patients

OBJECTIVE Previous studies have demonstrated that bilateral internal mammary artery (BIMA) grafts lead to superior outcomes compared with single internal mammary artery grafts. This study examines whether cardiopulmonary bypass affects conduit-dependent outcomes of coronary artery bypass grafting (CABG) surgery. METHODS From 1994 to 2013, a total of 6666 patients underwent isolated CABG surgery at our institution. Of these procedures, 3548 (53.2%) were performed off pump. A BIMA-saphenous vein graft (SVG) was used in 1544, and 5122 had left internal mammary artery-SVGs. These 2 conduit groups differed significantly in baseline characteristics. Propensity matching based on 22 preoperative variables and using a nearest-neighbor matching algorithm was used to make balanced cohorts, resulting in 2 groups of 1006. To account for the influence of pump status on conduit selection, a second propensity score was developed for pump use. These cases were matched to create 4 patient cohorts of 353 patients each (a total of 1412), balanced for both conduit use and pump status. Late mortality was determined using the Social Security Death Index. RESULTS No difference was found in survival between patients receiving BIMA-SVGs on or off pump (78.9% vs 79.1%). BIMA-SVGs outperformed the left internal mammary artery-SVGs regardless of whether the procedure was performed off pump (73.9%) or on pump (69.9%). CONCLUSIONS This study demonstrates that the use of cardiopulmonary bypass does not significantly affect the long-term outcomes in these patients as long as full revascularization is achieved. In addition, these results are consistent with prior research showing that the use of BIMAs produces better outcomes than use of a single internal mammary artery when performing CABG.

Effects of a protocol-based management of type A aortic dissections.

BACKGROUND Ascending aortic dissections (AADs) require prompt diagnosis and surgical treatment. We present the results of implementing a multidisciplinary aortic dissection protocol on the outcomes of AAD treatment at a nonteaching hospital. METHODS From January 2002-December 2013, 54 patients with the diagnosis of AAD were treated at our institution. Thirty-seven (68.5%) were male with a mean age of 62.3 y. Cardiogenic shock was present in 25.9% of patients. An AAD protocol, focused on educating physicians on presenting signs and symptoms, adequate triaging, and the need for immediate surgical intervention, was implemented, alongside the standardization of surgical treatment. We divided the cohort into two eras, based on AAD programs implementation in 2006, to better assess the impact of this protocol. RESULTS Patients from the early era had significantly longer time from Emergency Department to the operating room, more postoperative occurrence of prolonged ventilation, and a longer postoperative hospital stay at 8.7 ± 8 versus 3.1 ± 2.6 h (P = 0.002), 63% versus 18% (P = 0.002), and 63% versus 18% (P = 0.002), respectively. The overall mortality for the cohort was 9.3%, decreasing from 12.5% before 2006 to 7.9% after 2006. CONCLUSIONS The implementation of a multidisciplinary aortic dissection protocol has resulted in faster diagnosis and transport of AAD cases from the emergency room to the operating room, improving outcomes. Our data support the concept that nonteaching institutions can deliver excellent care to patients with acute aortic emergencies.

Impact of New York Heart Association classification, advanced age and patient-prosthesis mismatch on outcomes in aortic valve replacement surgery

OBJECTIVES More elderly patients (>80 years of age) are being referred for aortic valve replacement (AVR) with or without CABG. Current risk stratification models may not accurately predict the preoperative risk in these patients. We sought to determine which perioperative variables were relevant in determining short-term (30-day to in-hospital) outcomes in our intuitions series of consecutive AVR and AVR+CABG surgeries. We constructed a novel variable, patient-prosthesis mismatch (PPM) in the presence of diminished functional status (NYHA) classification, and studied its role as a predictor of mortality risk. METHODS From 2006 to 2010, 509 patients undergoing AVR or AVR+CABG were evaluated. We created four groups based on the age and procedure (AVR >80, AVR+CABG >80, AVR <80 and AVR+CABG <80). PPM was defined as a calculated effective orifice area index value of ≤ 0.85, and it was calculated from manufacturer-generated charts. In-hospital and 30-day outcomes were assessed using the Chi-square and logistic regression analyses. RESULTS Overall observed 30-day mortality for all groups was lower (n = 8, 1.6%) than the STS-predicted mortality. Reoperation and PPM+NYHA class III-IV were associated with short-term mortality, but age >80 years was not. Octogenarians referred for surgery often had advanced heart failure. CONCLUSIONS Overall, short-term outcomes after AVR with or without CABG were excellent and lower than predicted by the STS model. The low risk of AVR with CABG supports the consideration for earlier surgical referral and intervention for patients with a high likelihood of aortic stenosis progression before the onset of advanced heart failure ensues, regardless of the age. This should help further decrease the already very low mortality observed in these series. Efforts to avoid PPM in the setting of advanced heart failure may improve short-term results in this subset of patients.

Comparative genome-wide transcriptional analysis of human left and right internal mammary arteries

In coronary artery bypass grafting (CABG), the combined use of left and right internal mammary arteries (LIMA and RIMA) - collectively known as bilateral IMAs (BIMAs) provides a survival advantage over the use of LIMA alone. However, gene expression in RIMA has never been compared to that in LIMA. Here we report a genome-wide transcriptional analysis of BIMA to investigate the expression profiles of these conduits in patients undergoing CABG. As expected, in comparing the BIMAs to the aorta, we found differences in pathways and processes associated with atherosclerosis, inflammation, and cell signaling - pathways which provide biological support for the observation that BIMA grafts deliver long-term benefits to the patients and protect against continued atherosclerosis. These data support the widespread use of BIMAs as the preferred conduits in CABG.

Spontaneous Rupture of a Nonaneurismatic Ascending Thoracic Aorta

Abstract  Spontaneous rupture of the ascending thoracic aorta without any history of aneurysm, trauma, infection, dissection, or previous surgery is a very rare and potentially lethal event. We report a case of spontaneous rupture of the ascending aorta treated successfully. While the etiology is still unclear, diagnosis with bedside transesophageal echocardiography prompted emergent surgical intervention.