Waiting for cardiac surgery: results of a risk-stratified queuing process.

BACKGROUND: The Queen Elizabeth II Health Sciences Centre uses a weekly peer-review conference of cardiovascular experts to prioritize each surgical case to 1 of 4 queues with the use of standardized criteria of coronary anatomy, stress test result, and symptoms. We examined the hazard of waiting as well as the impact of waiting on surgical outcomes. METHODS AND RESULTS: Analysis was performed for 2102 consecutive patients queued for CABG, aortic valve replacement, or CABG+aortic valve replacement between January 1, 1998, and December 31, 1999. Among 1854 patients undergoing surgery, median waiting times on the respective queues were as follows: in-house urgent group, 8 days; semiurgent A group, 37 days; semiurgent B group, 64 days; and elective group, 113 days. There were 13 deaths (12 cardiac) that occurred during the waiting period (0.7% of the patients). Of the 8.7% patients upgraded to a more urgent queue, 86.1% required hospitalization before surgery. Although female sex was not associated with prolonged waiting time, it was predictive of urgent status (P=0.001). The incidence of postoperative complications was 25.0%, and operative mortality was 2.86%. Both were more frequent among patients undergoing surgery early (P=0.01); however, this difference was attributable to the in-house urgent queue. The median length of stay was 7 days for all patients and was not affected by waiting time. CONCLUSIONS: Death and upgrades while the patients were waiting tended to occur early in the queuing process, and prolonged waiting was not associated with worse surgical outcomes. The cost of reducing waiting times could in part be offset by prevention of hospital admissions among upgraded patients.

Composite arterial grafts versus conventional grafting for coronary artery bypass grafting.

OBJECTIVES: Composite arterial grafts for coronary artery bypass grafting surgery allow complete arterial revascularization but are limited by the inflow of a single internal thoracic artery supplying all the grafted vessels. We reviewed the safety of composite arterial grafts using either bilateral internal thoracic arteries or a single internal thoracic artery and radial artery. METHODS: From January 1999 to July 2002, 402 consecutive patients receiving composite grafts only were compared to a control group of patients (n = 542) undergoing coronary artery bypass grafting with internal thoracic artery and saphenous veins operated upon by the same surgeons. Two different statistical approaches were used to compare groups in this retrospective analysis. First, propensity score analysis with greedy matching technique was used to match patients from each group. Second, a multivariate analysis was performed looking at a combined patient outcome of death, intra-aortic balloon counterpulsation utilization, myocardial infarction, stroke, and prolonged ventilation on all patients in both groups. RESULTS: After matching by propensity score, the major clinical outcomes in composite arterial (n = 249) and control (n = 249) groups were found to be similar. The in-hospital mortality in the composite group was 1.2% as compared with 0.4% in matched patients (P =.62). However, patients in the composite group were found to have a significantly longer pump time (P <.0001), longer clamp time (P <.0001), increased incidence of prolonged mechanical ventilation (12.8% vs 4.8%; P =.002), and higher incidence of combined morbidity outcome (13.6% vs 6.4%; P =.007) as compared with matched patients. Multivariable analysis showed that composite arterial grafting was an independent predictor of the combined morbidity outcome with an odds ratio of 2.1 (1.2-3.7). CONCLUSIONS: These findings suggest that composite arterial grafting may be associated with an increase in risk-adjusted patient morbidity when compared with a conventional coronary artery bypass grafting group, although a mortality difference was not demonstrable.

Is body size the cause for poor outcomes of coronary artery bypass operations in women?

Although small body size and coronary artery diameter are recognized as major contributors to the increased risk of coronary artery bypass grafting in women, few studies have established the independent influence of body size and gender on outcome. We studied 7025 consecutive patients (5694 men, 1331 women) undergoing isolated coronary artery bypass grafting between 1990 and 1994. Women were older, had higher preoperative prevalences of urgent operation because of unstable angina, diabetes, peripheral vascular disease, hypertension, and single-vessel coronary artery disease (p < 0.0001), and a lower prevalence of left ventricular ejection fraction 40% or less (p < 0.0001). The prevalences of operative mortality (men, 1.8%; women, 3.5%), low-output syndrome (men, 6.6%; women, 14.8%), and myocardial infarction (men, 2.8%; women, 5.5%) were higher in women (p < 0.0001). Patients were divided into quartiles for body surface area, weight, height, and body mass index. For both men and women, there was no difference in operative mortality between the highest and lowest quartiles of body size. Women, however, had a higher prevalence of operative mortality than men in the lower quartiles of body surface area, height, and weight and in the higher quartiles of body mass index. Among men, the prevalence of low-output syndrome increased (p < 0.0001) with decreasing body surface area, weight, and body mass index, suggesting that body size did influence the prevalence of low-output syndrome. However, women had a higher prevalence of low-output syndrome than men in every category and quartile of body size (p < 0.0001). Multivariable analysis identified gender as a significant determinant of operative mortality (odds ratio 1.83, 95% confidence interval 1.27 to 2.64) and low-output syndrome (odds ratio 2.52, 95% confidence interval 2.05 to 3.11). When multivariable adjustments were made for body size and preoperative risk factors, gender remained a predictor of both operative mortality and low-output syndrome. Multivariable assessment of risk for men and women separately identified that urgent operation was a predictor of operative mortality (odds ratio 2.52, 95% confidence interval 1.32 to 5.61) and low-output syndrome (odds ratio 1.57, 95% confidence interval 1.14 to 2.17) in women but not men. In conclusion, the increased risk of coronary artery bypass grafting in women may be explained in part by dramatic differences in preoperative risk factors between men and women. In both men and women, small body size did not increase the risk of operative mortality, but may have contributed to the risk of low-output syndrome.(ABSTRACT TRUNCATED AT 400 WORDS)

Exercise oximetry versus spirometry in the assessment of risk prior to lung resection.

BACKGROUND: Spirometry remains a standard method of assessing patient risk prior to lung resection despite its poor sensitivity and specificity. This study compares the relative ability of standardized exercise oximetry and spirometry--forced expiratory volume in the first second--to predict morbidity and mortality after lung resection. METHODS: The study comprised a retrospective review of 396 consecutive patients of whom 299 underwent both oximetry and spirometry. Oximetry was undertaken during standard exercise under the supervision of a single physical therapist. Spirometry identified 46 patients with a forced expiratory volume in the first second of less than 1.5 L who were considered to be high risk. Exercise oximetry was used to identify patients with arterial oxygen desaturation at rest, while walking on level ground, or while climbing two flights of stairs (n = 65). RESULTS: Compared with spirometry, exercise oximetry more reliably predicted home oxygen requirements (p < 0.001), need of admission to the intensive care unit (p < 0.05), prolonged hospital stay (p < 0.001), and respiratory failure (p < 0.05). Oximetry identified 50% of the patients who died, all of whom had a forced expiratory volume in the first second of greater than 1.5 L. Despite its superior predictive value, the sensitivity of oximetry remained low. CONCLUSIONS: We conclude that standardized exercise oximetry is a superior screen of the high-risk patient than spirometry (forced expiratory volume in the first second) prior to pulmonary resection when there are no other risk factors noted on initial history and physical examination. A prospective, randomized trial is required to substantiate this conclusion.

Inaccurate and misleading valve sizing: a proposed standard for valve size nomenclature.

BACKGROUND: The sizes with which manufacturers label valves are nonuniform and haphazard. This has led to confusion and inappropriate comparisons of hemodynamics between valves with the same labeled size. Hemodynamic performance of valves is primarily determined by the internal diameter (ID) of their orifice. METHODS: The purpose of this study was to determine the ID and external diameter of aortic valves used at our institution and compare the measurements to manufacturers' labeled sizes. We also evaluated valve size (ID, manufacturers' labeled size) in 527 patients undergoing isolated aortic valve replacement between 1990 and 1996. RESULTS: We demonstrated that no two manufacturers' tissue or mechanical valves have the same ID or external diameter for a given labeled size. The labeled size of tissue valves was 1 to 4 mm larger than the measured ID. The labeled size of mechanical valves was 3 to 5 mm larger than the measured ID. The St. Jude HP mechanical valve has a greater ID than all other mechanical valves for each labeled size. Among 403 patients operated on for predominant aortic stenosis, those patients receiving the Toronto Stented Porcine Valve (n = 98) had a larger mean ID (22.3+/-1.9 mm) than 204 patients receiving stented tissue valves (ID = 20.9+/-1.9 mm) and the 101 patients receiving mechanical valves (ID = 19.3+/-1.9 mm, p < 0.0001). However, when the manufacturers' labeled size was used as a measure of the size, the results were greatly exaggerated in favor of the Toronto Stented Porcine Valve (ID = 26.3+/-1.9 mm) compared with stented tissue valves (ID = 23.1+/-2.1) or mechanical valves (ID = 23.6+/-1.9) (p < 0.0001). CONCLUSIONS: Manufacturers' labeling of valves is nonuniform and may lead to erroneous comparisons and conclusions of hemodynamic differences between valves. We therefore recommend a standardized nomenclature for the size of all valves based on the ID measurement.

Randomized study of right ventricular function with intermittent warm or cold cardioplegia.

BACKGROUND: Transient right ventricular dysfunction has been previously documented after bypass operations despite adequate myocardial protection with intermittent antegrade cold blood cardioplegia. Recently warm blood cardioplegia has been interrupted during construction of distal anastomoses to improve visualization. The effects of intermittent antegrade warm blood cardioplegia, and the resultant periods of right ventricular normothermic ischemia, on postoperative right ventricular function are unknown. METHODS: To assess the effects of cardioplegia on right ventricular protection, 52 patients undergoing isolated bypass grafting were randomized to intermittent warm or cold blood cardioplegia. The two groups were similar with respect to age, sex, ventricular function, and right coronary stenoses. Cross-clamp times were similar (warm, 64 +/- 22 minutes; cold, 63 +/- 15 minutes; not significant). The cumulative time of cardioplegia interruption was longer in the cold group (42 +/- 8 minutes) than in the warm group (31 +/- 14 minutes; p < 0.002). A rapid-response thermodilution catheter was employed to assess postoperative right ventricular ejection fraction and end-diastolic and end-systolic volume indices. RESULTS: The right ventricular ejection fraction was greater in the warm group at 6 hours (warm, 0.46 +/- 0.06; cold, 0.37 +/- 0.08; p < 0.05) and 8 hours (warm, 0.43 +/- 0.08; cold, 0.37 +/- 0.08; p < 0.05) postoperatively. The right ventricular end-diastolic volume index was less in the warm group 8 hours postoperatively (warm, 83 +/- 11 mL/m2; cold, 94 +/- 16 mL/m2; p < 0.05). There were no differences in pulmonary arterial pressures or right ventricular stroke work index. CONCLUSIONS: Despite intermittent normothermic ischemia of half the cross-clamp time, patients receiving warm cardioplegia maintained right ventricular hemodynamics after bypass grafting.

Can patients with left main stenosis wait for coronary artery bypass grafting?

BACKGROUND: The economic impact of health care reforms may result in waiting lists for coronary artery bypass grafting. This study was designed to examine the clinical results of patients with left main stenosis who were placed on a triaged wait list for operation. METHODS: Data were collected prospectively on 2,145 patients undergoing isolated coronary artery bypass grafting between 1989 and 1994. Critical left main stenosis (LMS, 50% or more stenosis) was present in 281 patients, and 1,864 patients had no left main disease, or a left main stenosis of less than 50% (no LMS). RESULTS: The average time from angiography to operation was shorter in patients with LMS (LMS 38 +/- 46 days versus no LMS 84 +/- 71 days; p = 0.0001). Two patients in the LMS group died; they had declined operation. Four patients suffered non-Q wave myocardial infarctions, all of whom subsequently underwent operation with no perioperative complications. The presence of LMS did not influence operative mortality (LMS 2.8% versus no LMS 1.3%), the incidence of low output syndrome (LMS 8.3% versus no LMS 5.4%), or the incidence of perioperative myocardial infarction (LMS 3.8% versus no LMS 4.2%). To examine the effect of waiting time on outcomes, patients with LMS were divided into early (operation 10 days or less after angiography) and late revascularization groups (more than 10 days). Operative mortality, low output syndrome, and myocardial infarction were similar in the early and late groups. Patients in the early group were more likely to have New York Heart Association functional class IV symptoms (64% versus late 22%; p < 0.0001), unstable angina (87% versus late 65%; p < 0.0001), or a recent preoperative myocardial infarction (17% versus late 2%; p < 0.0001). CONCLUSIONS: Carefully selected patients with significant left main stenosis can safely wait for operation with a low risk of complications. Early surgical intervention is allocated to patients with severe symptoms or recent preoperative myocardial infarction.

Left ventricular mass regression early after aortic valve replacement.

BACKGROUND: Regression of left ventricular hypertrophy is an important and well-recognized salutary effect of aortic valve replacement. The earliest evidence of left ventricular mass regression after aortic valve replacement and the influence of prosthesis type are not well known, and were the focus of this study. METHODS: Transthoracic echocardiography was used to measure left ventricular mass index preoperatively and before discharge in 57 consecutive patients undergoing isolated aortic valve replacement (with or without coronary artery bypass grafting). RESULTS: Three patients were excluded from the study because of inability to obtain accurate M-mode echocardiographic images for left ventricular mass measurement preoperatively (1) or postoperatively (2). Of the remaining 54 patients, mechanical bileaflet valves were used in 19, stented tissue bioprostheses were implanted in 15, and a stentless porcine bioprosthesis was chosen for 20. Postoperative echocardiograms were obtained 4.9 +/- 2.3 days after aortic valve replacement (range, 2 to 9 days). A two-way repeated-measures analysis of variance demonstrated a significant reduction of left ventricular mass index before discharge (preoperative 141.4 +/- 45.2 g/m2, postoperative 127.5 +/- 32.8 g/m2; p = 0.0005) but no differences between prostheses. CONCLUSIONS: Left ventricular mass regression begins early after aortic valve replacement, probably because of reduction of transvalvular gradients and left ventricular wall stress. At least in the very early postoperative period, the type of prosthesis does not influence the extent of mass regression.

ICU readmission after cardiac surgery.

OBJECTIVES: The increasing cost of intensive care unit (ICU) care and limited resources lead us to evaluate predictors of ICU readmission in a large group of patients undergoing coronary artery bypass surgery (CABG) at one institution. METHODS: Two thousand one hundred and seventeen consecutive patients undergoing CABG surgery between January 1999 and August 2001 were reviewed retrospectively. The reasons for readmission were determined by reviewing the physician's progress notes, the nurse's progress notes and the discharge summary. RESULTS: A total of 75 patients were readmitted to ICU during the study period for a readmission rate of 3.6%. Eight of these were readmitted a second time, and three a third time, for a total of 86 readmissions. Forty-seven patients died, for a mortality of 2% among patients that were not readmitted to the ICU, compared to 17% among those who were readmitted (P<0.0001). Median hospital length of stay was 6 days for patients not readmitted and 23 days for those readmitted (P<0.0001). The most common reason for readmission was respiratory failure, accounting for 47% of readmissions (n=40). Multivariate analysis using a stepwise logistic regression analysis revealed that preoperative renal failure (odds ratio 2.13; CI 1.03-4.41) and prolonged mechanical ventilation of >24 h (odds ratio 10.52; CI 6.18-17.91) were the only independent predictors for readmission to the ICU after CABG. CONCLUSIONS: Identification of patients that have preoperative renal failure or that required initial ventilation for more than 24 h after CABG may help to identify patients at risk of ICU readmission. Preemptive strategies designed to optimize these high-risk patients may improve outcomes.

Preoperative prediction of prolonged mechanical ventilation following coronary artery bypass grafting.

OBJECTIVE: Few studies have attempted to evaluate who would require prolonged mechanical ventilation following heart surgery. The objectives of this study were to identify predictors of prolonged ventilation in a large group of coronary artery bypass grafting (CABG) patients from a single institution. METHODS: One thousand, eight hundred and twenty-nine consecutive patients undergoing CABG were reviewed retrospectively and evaluated for preoperative predictors of prolonged ventilation which included: age, gender, ejection fraction (EF), renal function, diabetes, angina status, New York Heart Association Class, number of diseased vessels, urgency of the procedure, re-operation, chronic lung disease (COPD) and intraoperative variables such as IABP, inotropes, stroke and myocardial infarction. Prolonged ventilation was defined as > or = 24 h. Stepwise logistic regression analysis was performed. RESULTS: Patients were on average 65.4+/-10.6 years of age, 30% were diabetic, 80% had triple vessel disease and 93% were of functional class III/IV. The mean ejection fraction was 60+/-16 percent. Overall peri-operative mortality was 2.7%. There were 157 patients that required prolonged ventilation with a peri-operative mortality of 18.5% (P < 0.001). Preoperative independent predictors of prolonged ventilation were found to be: unstable angina (OR 5.6), EF < 50 (OR 2.3), COPD (OR 2.0), preop. renal failure (OR 1.9), female gender (OR 1.8) and age > 70 (OR 1.7). Based on these predictors, a model was created to estimate of the risk of prolonged ventilation in individual patients following CABG with results ranging from < or = 3% in patients without any risk factors to > or = 32% in patients with five or more independent risk factors. Certain intraoperative variables were strong predictors of prolonged ventilation and included: stroke (OR 12.3), re-operation for bleeding (OR 6.9) and perioperative MI (OR 5.8). CONCLUSION: We were able to create a stable model where several preoperative and intra-operative variables were shown to be predictive of prolonged ventilation after CABG surgery. The ability to identify patients at increased risk for prolonged ventilation may allow the development of pre-emptive strategies and more effective resource allocation.

The influence of risk on the results of warm heart surgery: a substudy of a randomized trial.

OBJECTIVE: The Warm Heart Investigators Trial randomized isolated coronary bypass patients to cold or warm cardioplegia, and demonstrated that warm cardioplegia significantly reduced the prevalence of low output syndrome and myocardial infarction (as defined by CKMB enzyme release). This study was designed prospectively as a subanalysis of the original trial, to determine the effect of warm heart surgery on high risk patients, who were anticipated to derive the major benefit from warm cardioplegia. METHODS: The prespecified endpoint for this study was a composite outcome of morbidity and mortality (death and/or low output syndrome and/or enzymatic myocardial infarction). Only patients with complete data for all outcomes were included, totalling 1374 patients (692 warm cardioplegia, 682 cold cardioplegia) who were randomized in the Warm Heart Investigators Trial. High medium and low risk patients were identified by a multivariate model of predicted risk for the study outcome. RESULTS: Analysis of the independent and interactive influence of cardioplegia technique and predicted risk demonstrated that warm cardioplegia significantly reduced the overall prevalence of morbidity and mortality (warm: 15.9 versus cold: 25.2%, P < 0.01). However, no significant differences in warm-cold effects were detected among risk terciles. Cardioplegia technique had a similar differential influence on mortality and morbidity in low risk patients (warm: 7.3, cold: 17.4%) as it did in high risk patients (warm: 31.1, cold: 39.9%). CONCLUSIONS: Although our analysis confirms the overall benefits of warm cardioplegia, our unanticipated finding in high risk subjects may be explained by the fact that morbidity and mortality in that patient subgroup is caused not only by poor myocardial protection, but by other clinical and technical factors. Further studies are necessary to identify those patients who might benefit most from improved myocardial protection techniques.

Ten-year heart transplantation experience at the MARITIME HEART CENTER: does volume affect results?

OBJECTIVE: To evaluate the experience of a small volume Canadian heart transplantation centre. DESIGN: Ninety-four consecutive primary heart transplants were performed from 1988 to 1998 at the Maritime Heart Center, Halifax, Nova Scotia, with 100% follow-up. Kaplan-Meier survival analysis was used. RESULTS: The mean recipient age was 48.5+/-12.3 years and donor age 33+/-13.2 years. Eighty per cent of recipients were men. The prevalence of elevated pulmonary vascular resistance (4 or more Wood units) was 20.2%. Etiology of heart failure was ischemic cardiomyopathy (50%), dilated cardiomyopathy (40.9%) and congenital heart disease (9.1%). Survival was 85.9% at one year (n=71), 75.3% at five years (n=33) and 60.5% at eight years (n=8). There was a trend toward survival benefit with human leukocyte antigen (HLA) -DR matching, body mass index ratio of donor to recipient greater than 0.8, ischemic time less than 90 mins and male donors. There was no effect on survival with donor or recipient age, recipient sex, diabetes, hypertension, hypercholesterolemia, elevated pulmonary vascular resistance and HLA-A/B mismatch. CONCLUSIONS: Excellent survival at one and five years following heart transplantation is reported that compares favourably with results published by the International Society for Heart and Lung Transplantation.

Myocardial scintigraphy correlates poorly with coronary angiography in the screening of transplant arteriosclerosis.

BACKGROUND: Coronary angiography remains an important screening tool for transplant coronary arteriosclerosis (TxCAD) after heart transplantation despite criticism that it underestimates the incidence of TxCAD. In an effort to improve TxCAD incidence estimation, several methods of screening have been proposed. In the present study, the incidence of TxCAD assessed by both yearly coronary angiography and stress myocardial scintigraphy imaging was reviewed. PATIENTS AND METHODS: Ninety-nine consecutive primary heart transplantations were performed from 1988 to 1999. The standard immunosuppression protocol consisted of the introduction of antilymphocyte globulin and steroids, while maintenance therapy was with cyclosporine, imuran and steroids. Coronary angiography and a stress 2-methoxyisobutyl-isonitrile perfusion scan were performed yearly. TxCAD was defined by angiographic evidence of luminal abnormality by catheterization, or a perfusion abnormality at rest or after stress on myocardial scintigraphy. RESULTS: The mean recipient age was 49+/-12 years and the mean donor age was 33+/-13 years. The etiology of heart failure was ischemic cardiomyopathy (50%), dilated cardiomyopathy (41%) and congenital heart disease (9%). The freedom from angiographic TxCAD was 92% at one year, 64% at five years and 35% at eight years. The freedom from nuclear imaging TxCAD was 92% at one year, 69% at five years and 44% at eight years. However, a diagnosis of TxCAD by angiography only correlated with a diagnosis of TxCAD by nuclear imaging 52.8% of the time in the same patient, with a median time between studies of one month. CONCLUSION: The overall incidence of TxCAD diagnosed by angiography and nuclear imaging appears similar but correlates poorly in patients, casting doubt on the routine use of myocardial scintigraphy for screening TxCAD.

How established wait time benchmarks significantly underestimate total wait times for cardiac surgery.

BACKGROUND: Wait times for cardiac surgery are well established but may not reflect the total wait time patients experience. METHODS: The Maritime Heart Center (Halifax, Nova Scotia) cardiac surgery database was used to identify all consecutive patients who underwent elective coronary artery bypass graft surgery between 2002 and 2005 from a single urgency queue. The provincial physician billing database provided a timeline record of dates, physician visits, and diagnoses or procedures performed for each patient. This information was used to assess total and component wait times leading to cardiac surgery. RESULTS: A total of 705 consecutive patients were included and stratified based on geographical location: urban Halifax Regional Municipality (HRM; n=222), urban non-HRM (n=220) and rural (n=263). Patients from all regions did not differ in age, sex, comorbidities or ventricular function. Using a traditional definition of wait time (time listed), patients waited a median of 56 days (interquartile range [IQR] 38 to 77 days). In comparison, the total wait times based on the time from presentation to surgery were a median of 109 days (IQR 56 to 184 days) for HRM, a median of 121 days (IQR 77 to 184 days) for urban non-HRM and a median of 123 days (IQR 79 to 169 days) for rural patients (P-value nonsignificant). Two modes of presentation emerged that were not influenced by a patient's geographical location. Patients who presented to the emergency department (n=229) waited a median of 73 days. This was significantly less than patients who presented to their family physician (n=476), who waited a median of 135 days (P<0.001). The difference in overall wait for patients presenting to the emergency room was a result of a shorter wait time for referral to a specialist and from seeing a specialist to catheterization. CONCLUSION: The present pilot study demonstrated that total patient wait times for cardiac care and surgery in Nova Scotia are significantly longer (more than twofold) than traditionally reported wait times for surgery alone.

St. Jude SPV versus Medtronic Freestyle: a single institution comparison of two stentless aortic valves.

BACKGROUND: Improved hemodynamics with the SPV and Freestyle bioprostheses compared to stented valves have been reported. It has been suggested that there is more aortic insufficiency (Al) with the Freestyle than with the SPV valve. This study was designed to assess the hemodynamic performance of these two valves implanted at a single institution with all echocardiograms reviewed by one echocardiographer. METHODS: From 1993 to 1997 112 patients underwent aortic valve replacement with stentless aortic valves (69 SPV, 43 Freestyle). There were no major preoperative differences in patient age, gender, NYHA class, or ejection fraction between groups. Echocardiographic assessment was obtained at discharge, 3 to 6 months following surgery, and yearly thereafter. RESULTS: Mean follow-up was 15.9 months for the SPV and 28.6 months for the Freestyle. Both valves have excellent valve areas and low transvalvar mean gradients. There is a trend for more Al in the SPV group. At 1 year, 1+ or greater Al was present in 11 of 42 SPV patients compared to 2 of 34 Freestyle patients (p = 0.030). Al has tended to remain stable over time, has not progressed, and is not clinically evident. DISCUSSION: Differences in the previously reported incidence of aortic insufficiency with these valves may have more to do with the method of reporting Al than its actual frequency. Within our institution, there has been slightly more mild Al with the SPV valve than with Freestyle. Long-term follow-up of these valves is needed to determine if the Al progresses or becomes clinically important. To date there is no such trend with either valve.

Changing pattern of valve surgery.

BACKGROUND: Advances in surgical technique and perioperative myocardial protection have reduced the risk of aortic and mitral valve surgery. Improved methods of valve repair have reduced the proportion of patients who require valve replacement. However, patients who require valve replacement often have advanced disease and/or extensive calcification and may therefore be at increased risk for perioperative morbidity and mortality. METHODS AND RESULTS: We reviewed the results of 2898 patients who underwent aortic (AVR) or mitral (MVR) valve replacement at the Toronto Hospital. We compared patients who underwent surgery between January 1982 and December 1986 (early group) with those who were operated on between January 1989 and December 1993 (late group). The univariable and multivariable predictors of postoperative low-output syndrome (LOS) and operative mortality (OM) were determined for each time period. A total of 1779 patients underwent AVR (late, n = 997; early, n = 782). Multivariable analyses revealed that the late group had significantly more patients with independent pre-epidemiology operative risk factors for both OM and LOS. Despite the greater proportion of high risk patients, the incidence of postoperative LOS was lower in the late group (10% versus early, 14%; P = .012). There was no difference in OM between the two groups (late, 3.4% versus early, 3.7%; P = .732). A Total of 1119 patients underwent MVR (late, n = 493; early, n = 626). Compared with the early group, the late group had significantly more patients with preoperative multivariable risk factors for OM and LOS. There was no difference in postoperative LOS (late, 19% versus early, 21%; P = .361) or OM between the two groups (late, 5.8% versus early, 6.9%; P = .432). CONCLUSIONS: Despite an increase in high-risk patients, there was no significant increase in mortality or morbidity associated with aortic or mitral valve surgery.

Early experience with stentless versus stented valves.

BACKGROUND: The Toronto stentless porcine valve (SPV) was designed to improve hemodynamics after aortic valve replacement by maximizing available flow area in comparison to stented valves (STD). METHODS: To assess possible hemodynamic differences between STD and SPV, 59 patients undergoing isolated aortic valve replacement (+/-coronary artery bypass graft) were prospectively evaluated by preoperative and 3- to 6-month postoperative echocardiography. Among these, 23 patients received a STD, whereas 36 received the Toronto SPV. RESULTS: The mean size (mm) of SPV implanted was larger (SPV, 26.6+/-2.1; STD, 24.0+/-2.9; P=0.0002). Patients receiving STD valves were older and had a higher prevalence of coronary artery disease and congestive heart failure. There were no preoperative differences in left ventricular mass index (g/mo2), peak or mean pressure gradients (mmHg), effective orifice area (cm2), extent of fractional shortening (%), or velocity of circumferential shortening (cf/sec). ANOVA demonstrated a significant reduction in left ventricular mass index at 3 to 6 months (P=.0001) but no differences in left ventricular mass index regression between groups (STD, -28.8+/-37.5; SPV, -31.2+/-32.4; P=.36). Effective orafice area was increased postoperatively (P=.0001), particularly among SPV cases (STD, 1.5+/-0.4; SPV, 1.9+/-0.7; P=.01). Postoperative left ventricular mass index and mean pressure gradient were reduced (P=.0001) but did not differ between groups. Fractional shortening and velocity of circumferential shortening were greater in the SPV patients at 3 to 6 months after aortic valve replacement (P=.0004 and .0001, respectively), and an interactive effect was seen between time and prosthetic group (P=.0028 and .032, respectively). CONCLUSIONS: In a consecutive series of patients, we identified no hemodynamic differences between STD and SPV, although ventricular function improved after SPV. Because of the nonrandomized nature of the study, selection bias may have accounted for some of the observed results. A prospective, randomized trial is necessary to determine the hemodynamic advantages, if any, of the SPV valve.

Coronary artery bypass grafting in patients with non-dialysis-dependent renal insufficiency.

BACKGROUND: Preoperative renal failure increases the morbidity and mortality of coronary artery bypass graft (CABG) surgery. The results of CABG in patients with non-dialysis-dependent, mild renal insufficiency are unknown. METHODS: From a population of 2978 consecutive patients undergoing isolated CABG from 1990 to 1996, 38 patients with preoperative renal insufficiency (Renal group; serum creatinine >150 micromol/L) were identified and matched on six prognostic variables to a cohort of 152 control patients (Control group). Two patients with preoperative dialysis-dependent renal failure were excluded from analysis. RESULTS: Compared to the overall population, the Renal group were more likely to be over age 70, diabetic, hypertensive, and suffer from peripheral vascular disease and left ventricular dysfunction. Compared to the Control group, the Renal group were more likely to require perioperative blood transfusions (P<.001) and had a greater requirement for postoperative dialysis (P<.01). The Renal group had longer ventilation times, intensive care unit stay, and postoperative hospital stay. Mild renal insufficiency was found to be an independent predictor of postoperative low output syndrome (odds ratio=3.6). CONCLUSIONS: Mild renal insufficiency, even in the absence of dialysis, increases the risk of blood transfusion, low output syndrome and prolonged the length of intensive care unit and postoperative stay for patients undergoing CABG.

Multiple arterial grafts. Radial versus right internal thoracic arteries.

BACKGROUND: Left internal thoracic artery (LITA) grafts to the left anterior descending coronary artery (LAD) during coronary bypass surgery (CABG) have greater patency rates than saphenous vein grafts and reduce long-term cardiac morbidity and mortality rates. The benefits of multiple versus single arterial grafts and the role of different arterial conduits with respect to short- and medium-term outcome remains controversial. The purpose of this study was to compare the perioperative and intermediate-term results of: (1) patients receiving 2 arterial grafts versus 1 arterial graft and (2) patients receiving a right internal thoracic artery (RITA) versus a radial artery (RA) as the second arterial graft. METHODS AND RESULTS: Retrospective analysis of prospectively gathered data on consecutive patients undergoing isolated CABG at our institution between 1989 and 1996 was conducted. The first section of the study compared outcomes for 1 arterial graft (LITA to LAD, n = 2333) versus 2 arterial grafts (LITA + RA or LITA + RITA, n = 378). The second section of the study compared outcomes for the RITA (n = 132) versus the RA (n = 171) as second arterial grafts since 1992, when the radial series was initiated. Part I: By multivariable stepwise logistic regression, the use of 1 arterial graft was associated with an increased incidence of perioperative cardiac morbidity and mortality (odds ratio 2.2, 95% confidence interval 1.4 to 3.3), with the use of our current patient selection criteria. Double-arterial graft patients had a nonsignificant trend toward increased intermediate-term actuarial survival (P = 0.12) and cardiac event-free survival (P = 0.09). Part II: Comparison of preoperative demographics revealed a higher incidence of diabetes (27% vs 11%, P < 0.001), peripheral vascular disease (16% vs 8%, P = 0.03), and elderly age (13% vs 2%, P = 0.001) in patients receiving an RA versus those receiving a RITA as the second arterial graft. Perioperative outcome analysis revealed a decreased intensive care unit stay in the RA versus RITA group (median 30.4 vs 36.2 hours, respectively, P = 0.005) but no significant difference in hospital length of stay. There was no significant difference in perioperative mortality or cardiac morbidity rates. RITA patients had a higher incidence of sternal wound infection (5.3% vs 0.6%, P = 0.01), however, and tended to have increased blood product transfusion rates (51% vs 40%, P = 0.06). CONCLUSIONS: The use of 2 arterial grafts is safe, with a reduction in perioperative cardiac morbidity or mortality rates compared with 1 arterial graft after adjustment for other risk variables. When comparing RITA to RA as second arterial grafts, patients receiving an RA have a lower incidence of sternal wound infection and decreased transfusion requirements, with no difference in perioperative or intermediate-term cardiac morbidity or mortality rates.