Gary L. Grunkemeier

Guidelines for Reporting Mortality and Morbidity After Cardiac Valve Interventions

uidelines for Reporting Mortality and Morbidity fter Cardiac Valve Interventions ary W. Akins, MD, D. Craig Miller, MD, Marko I. Turina, MD, icholas T. Kouchoukos, MD, Eugene H. Blackstone, MD, ary L. Grunkemeier, PhD, Johanna J. M. Takkenberg, MD, PhD, irone E. David, MD, Eric G. Butchart, MD, David H. Adams, MD, avid M. Shahian, MD, Siegfried Hagl, MD, John E. Mayer, MD, and ruce W. Lytle, MD The American Association for Thoracic Surgery, Beverly, Massachusetts; The Society of Thoracic Surgeons, Chicago, Illinois; and The European Association for Cardio-Thoracic Surgery, Windsor, Berks, United Kingdom

Patient outcome after aortic valve replacement with a mechanical or biological prosthesis: Weighing lifetime anticoagulant-related event risk against reoperation risk

OBJECTIVE Although the results of aortic valve replacement with different valve prostheses are well documented in terms of survival, the risks of (valve-related) events are less well explored. METHODS We used a dataset of 3934 patients who underwent aortic valve replacement with either a bioprosthesis (73%) or a mechanical prosthesis (27%) between 1982 and 2003 to simulate the outcome of patients after aortic valve replacement with either valve type. With the use of microsimulation, we compared total age and gender-specific life expectancy, event-free life expectancy, reoperation-free life expectancy, lifetime risks of reoperation, and valve-related events for both valve types. RESULTS The total follow-up was 26,467 patient-years. The mean follow-up was 6.1 years in the biological arm and 8.5 years in the mechanical arm. The mean age at implantation was 70 and 58 years for biological and mechanical prostheses, respectively, and the percentage of concomitant coronary artery bypass grafting was 47% and 28%, respectively. For a 60-year-old man, simulated life expectancy in years for biological versus mechanical prostheses was 11.9 versus 12.2, event-free life expectancy was 9.8 versus 9.3, and reoperation-free life expectancy was 10.5 versus 11.9. Lifetime risk of reoperation was 25% versus 3%. Lifetime risk of bleeding was 12% versus 41%. CONCLUSION Even for patients aged 60 years, event-free life expectancy is better with a bioprosthesis. Although the chance of reoperation is higher, the lifetime risk of bleeding is lower compared with a mechanical prosthesis. Comparing lifetime event risks between different types of valve prostheses provides more insight into patient outcome after aortic valve replacement and aids patient selection and counseling.

Does video-assisted thoracoscopic lobectomy for lung cancer provide improved functional outcomes compared with open lobectomy?

OBJECTIVE We evaluated video-assisted thoracic surgery (VATS) and open (OPEN) lobectomy for lung cancer and impact upon 6-month postoperative (postop) functional health status and quality of life. METHODS In this retrospective analysis of prospective, observational data, anatomic lobectomy with staging thoracic lymphadenectomy was performed with curative intent for lung cancer. OPEN consisted of either thoracotomy (TH) or median sternotomy (MS). Technique was selected on the basis of anatomic imperative (OPEN: larger or central; VATS smaller or peripheral tumours) and/or surgical skills (VATS lobectomy initiated in 2001). All patients completed the Short Form 36 Health Survey (SF36) and Ferrans and Powers quality-of-life index (QLI) preoperatively (preop) and 6 months postop. RESULTS A total of 241 patients underwent lobectomy (OPEN, 192; VATS, 49). OPEN included MS 128 and TH 64. Comparison of MS and TH patient demographics, co-morbidities, pulmonary variables, intra-operative variables, stage and cell type, postop complications and 6-month clinical outcomes found no differences, allowing grouping together into OPEN. The VATS group had better pulmonary function testing (PFT), more adenocarcinoma and lower stage. The VATS and OPEN groups did not differ regarding operating time, postop complications and operative or 6-month mortality. The VATS group had less blood loss, transfusion, intra-operative fluid administration and shorter length of stay. Comparing within each groups preop to 6-month postop data, VATS patients were either the same or better in all SF36 categories (physical functioning, role functioning - physical, role functioning - emotional, social functioning, bodily pain, mental health, energy and general health). The OPEN group, however, was significantly worse in SF36 categories physical functioning, role functioning - physical and social functioning. The preop and 6 months postop VATS versus OPEN QLI scores were not different. At 6 months postop, hospital re-admission and use of pain medication was less in the VATS group. In addition, the VATS group had better preservation of preop performance status. CONCLUSIONS VATS lobectomy for curative lung cancer resection appears to provide a superior functional health recovery compared with OPEN techniques.

Is Obesity a Risk Factor for Mortality in Coronary Artery Bypass Surgery

Background—The published articles examining obesity and CABG surgery contain conflicting results about the role of body mass index (BMI) as a risk factor for in-hospital mortality. Methods and Results—We studied 16 218 patients who underwent isolated CABG in the Providence Health System Cardiovascular Study Group database from 1997 to 2003. The effect of BMI on in-hospital mortality was assessed by logistic regression, with BMI group (underweight, normal, overweight, and 3 subgroups of obesity) as a categorical variable or transformations, including fractional polynomials, of BMI as a continuous variable. BMI was not a statistically significant risk factor for mortality in any of these assessments. However, using cumulative sum techniques, we found that the lowest risk-adjusted CABG in-hospital mortality was in the high-normal and that overweight BMI subgroup patients with lower or higher BMI had slightly increased mortality. Conclusions—Body size is not a significant risk factor for CABG mortality, but the lowest mortality is found in the high-normal and overweight subgroups compared with obese and underweight.

Aprotinin Does Not Increase the Risk of Renal Failure in Cardiac Surgery Patients

Background— Aprotinin is frequently used in high-risk cardiac surgery patients to decrease bleeding complications and transfusions of packed red blood cells (PRBC). Transfusions of PRBC are known to directly increase the risk of new onset postoperative renal failure (ARF) in cardiac surgery patients. A recent highly publicized report implicated aprotinin as an independent causal factor for postoperative renal failure, but ignored the potential confounding affect of numerical PRBC data on ARF. We sought to investigate that claim with an analysis that included all perioperative risk factors for renal failure, including PRBC transfusion data. Methods and Results— Prospectively collected patient data from 12 centers contributing to the Merged Cardiac Registry, an international multicenter cardiac surgery database, operated on between January 2000 and February 2006 were retrospectively analyzed. A previously published risk model for ARF incorporating 12 variables was used to calculate a baseline ARF risk score for each patient in whom those variables were available (n=15 174). After adding transfused PRBC data 11 198 patients remained for risk-adjusted assessment of ARF in relation to aprotinin use. Risk-adjusted multivariable analyses were carried out with, and without, consideration of transfused PRBC. Aprotinin was used in 24.6% (2757/11 198). The overall incidence of ARF was 1.6% (180/11 198) and was higher in the aprotinin subset (2.6%, 72/2757 versus 1.3%, 108/8441; P<0.001). The incidence of ARF directly and significantly increased with increasing transfusions of PRBC (P<0.001). Risk-adjusted analysis without transfused PRBC in the model suggests that aprotinin significantly impacts ARF (P=0.008; OR=1.5). However, further risk adjustment with the addition of the highly significant transfused PRBC variable (P<0.0001; OR=1.23/transfused PRBC) to the model attenuates the purported independent affect of aprotinin (P=0.231) on ARF. Conclusions— The increase in renal failure seen in patients who were administered aprotinin was directly related to increased number of transfusions in that high-risk patient population. Aprotinin use does not independently increase the risk of renal failure in cardiac surgery patients.

Receiver operating characteristic curve analysis of clinical risk models

Receiver operating characteristic (ROC) curve analysis is a useful method to measure the ability of a clinical risk model to discriminate between hospital deaths and survivors. Its use in medicine originated as a method for synthesizing the specificity and sensitivity of diagnostic tests across a spectrum of possible cut points. The area under the ROC curve can be interpreted as a probability of correct classification or prediction. We illustrate its use in three steps: first, with a dichotomous variable to introduce specificity and sensitivity; next, with a categorical risk factor (surgical urgency) to produce a primitive ROC curve; and finally, with a continuous risk factor (age) to approximate the usual ROC curve used for clinical risk models.

Prosthetic Valve Type for Patients Undergoing Aortic Valve Replacement: A Decision Analysis

BACKGROUND In two large, randomized, clinical trials long-term survival after aortic valve replacement (AVR) was similar for patients receiving tissue and mechanical aortic heart valve prostheses. Higher bleeding rates among patients with mechanical valves, who must receive permanent oral anticoagulation to prevent thromboembolism, were offset by higher reoperation rates for valve degeneration among patients with tissue valves. Because the average age of patients undergoing AVR and clinical practices have changed considerably since the randomized clinical trials were conducted, we performed a decision analysis to reassess the optimal valve type for patients undergoing AVR. METHODS We used a Markov state-transition model to simulate the occurrence of valve-related events and life expectancy for patients undergoing AVR. Probabilities of clinical events and mortality were derived from the randomized clinical trials and large follow-up studies. RESULTS Although the two valve types were associated with similar life expectancy in 60-year-old patients (mean age of patients in the randomized clinical trials), tissue valves were associated with greater life expectancy than mechanical valves (10.7 versus 11.1 years) in 70-year-old patients (currently mean age of AVR patients). For 70-year-old patients, the effects of major bleeding complications (24%) with mechanical valves substantially outweighed those of reoperation for valve failure (12%) with tissue valves at 12 years. Of the clinical practice changes assessed, the recommended valve type was most sensitive to changes in bleeding rates with anticoagulation. However, bleeding rates would have to be 68% lower than those reported in the European randomized clinical trial to affect the recommended valve type for 70-year-old patients. Reoperation rates would have to be five times higher, and mortality rates at reoperation would have to be four times higher to affect the recommended valve type for 70-year-old patients. CONCLUSIONS Although mechanical valves are preferred for AVR patients less than 60 years old, most patients currently undergoing AVR are elderly and would benefit more from tissue valves.

Long-term outcome, survival analysis, and risk stratification of dynamic cardiomyoplasty

METHODS To analyze the long-term outcome of dynamic cardiomyoplasty, we retrospectively studied 127 consecutive patients who underwent this procedure in Paris, France (n = 76), São Paulo, Brazil (n = 37), and Portland, Oregon (n = 14). Preoperative data were collected for patients operated on between January 1985 and June 1994 and examined with respect to effect on long-term survival. Patients had a mean age of 50 +/- 13 years and were predominantly male (82%). In 46% the cause of disease was ischemic. Concomitant operations were performed in 22 patients. RESULTS Operative mortality was 12% (15/127). Kaplan-Meier survival +/- standard error at 1 through 5 years was 73% +/- 4%, 57% +/- 5%, 49% +/- 6%, 44% +/- 6%, and 40% +/- 7%, respectively. There was a distinct improvement at 6 months in New York Heart Association functional class (3.2 +/- 0.05 vs 1.7 +/- 0.07, p < 0.0001) and a small but significant increase in left ventricular ejection fraction (20% +/- 0.8% vs 23% +/- 1.5%, p = 0.04). Ninety-day mortality was associated with low right ventricular ejection fraction, a blunted hemodynamic response to exercise testing, and requirement for an intraaortic balloon pump at the time of the operation. Using a stepwise Cox regression method of multivariable survival analysis (n = 101), we determined that atrial fibrillation, New York Heart Association class IV, high pulmonary capillary wedge pressure, and balloon pump use were independent variables simultaneously associated with poor overall survival. When metabolic testing variables were added to this model, peak oxygen consumption eliminated both pulmonary capillary wedge pressure and functional class from the model, albeit with fewer (n = 74) patients. CONCLUSION Dynamic cardiomyoplasty is an evolving therapy for symptomatic congestive heart failure, the results of which may be enhanced by intelligent, risk-sensitive patient selection.

A New Scoring System to Determine Thromboembolic Risk After Heart Valve Replacement

Objective—To determine the most important inflammatory and hematologic predictors of thromboembolism (TE) in patients undergoing valve replacement (VR) to be used in conjunction with clinical risk factors for preoperative risk profiling. Methods and Results—Preoperative and immediately postoperative clinical, echocardiographic, hematologic, biochemical and microbiological parameters were examined prospectively in 370 patients undergoing VR (249 AVR, 93 MVR, 28 DVR). Mean follow-up was 4.4 years (max 6.6 years; total 1566 pt/yrs), and 96 TE events were documented (28 major and 68 minor). INR data were collected on all patients. Laboratory values were considered elevated if they exceeded the 80th percentile of those of 70 controls with the same distribution of age and gender. IgA antibody to Chlamydia pneumoniae (CP)≥1:64 was considered indicative of significant infection. Predictors of TE on multivariate analysis following AVR were (hazard ratios): CP infection (2.6), previous TE (2.5), raised eosinophils (2.4), cancer history (2.1), postoperative infection (2.0), hypertension (2.0), CABG × 3/4 (2.0), and diabetes (1.9). Predictors of TE following MVR/DVR were raised mean platelet volume (4.0), raised factor VII (3.1), CP infection (2.7), previous mitral valvotomy (2.5), raised fibrinogen (2.2), and raised reticulocytes (2.0). These risk factors were additive when present in the same patient, enabling a scoring system to be developed that accurately predicted risk of TE based on number of risk factors. Conclusions—Selected blood tests and clinical risk factors provide a scoring system that accurately predicts TE risk and may guide prosthesis choice and antithrombotic management.

Ten year survival after coronary artery bypass surgery for angina in patients aged 65 years and older.

We have assessed the long-term results of coronary bypass surgery for angina from 1974 to 1983 in 1304 patients aged 65 years and older (group 1). Using actuarial techniques, we determined that the 5 year and 10 year survival rates for patients 65 years old or older were 81 +/- 2% and 65 +/- 3% (mean +/- SE), respectively. The patients aged 65 years and older were further subdivided into those aged 65 to 74 years (group 1a) and 75 to 84 years (group 1b) and were compared with 1700 patients aged 55 to 64 years (group 2). The operative mortality in the three subgroups was 3%, 3%, and 2%, respectively (p = NS). For coronary bypass surgery, the duration of hospital stay was significantly longer (p less than .0001) by a mean of 1 to 2 days for group 1 patients and the cost of hospitalization was higher by a mean of