Preoperative Exercise Capacity Research Articles

Surgical management and outcome of patients with chronic thromboembolic pulmonary hypertension: Results from an international prospective registry

Pulmonary endarterectomy is a curative surgical treatment option for the majority of patients with chronic thromboembolic pulmonary hypertension. The current surgical management and postoperative outcome of patients enrolled in an international registry on chronic thromboembolic pulmonary hypertension were investigated. The registry included newly diagnosed (≤6 months) consecutive patients with chronic thromboembolic pulmonary hypertension from February 2007 to January 2009. A total of 679 patients were registered from 1 Canadian and 26 European centers, of whom 386 (56.8%) underwent surgery. The median age of patients undergoing surgery was 60 years, and 54.1% were male. Previous pulmonary embolism was confirmed for 79.8% of patients. Perioperative complications occurred in 189 patients (49.2%): infection (18.8%), persistent pulmonary hypertension (16.7%), neurologic (11.2%) or bleeding (10.2%) complications, pulmonary reperfusion edema (9.6%), pericardial effusion (8.3%), need for extracorporeal membrane oxygenation (3.1%), and in-hospital mortality due to perioperative complications (4.7%). Documented 1-year mortality was 7%. Preoperative exercise capacity was predictive of 1-year mortality. Postoperative pulmonary vascular resistance predicted in-hospital and 1-year mortality. In patients evaluated within 1 year after surgery, the median pulmonary vascular resistance had decreased from 698 to 235 dyn x s x cm(-5) (95% confidence limit, 640-874 and 211-255, respectively, n = 70) and the median 6-minute walk distance had increased from 362 to 459 m (95% confidence limit, 340-399 and 440-473, respectively, n = 168). New York Heart Association functional class improved with most patients progressing from class III/IV to class I/II. Pulmonary endarterectomy is associated with a low in-hospital mortality rate and improvements in hemodynamics and exercise capacity.

Valoración de la capacidad preoperatoria al ejercicio como factor predictivo de supervivencia en enfermos sometidos a trasplante pulmonar

To make an independent evaluation of the capacity for exercise as a predictive factor in lung transplant recipients.Retrospective study.Lung transplant unit of the Intensive Care Unit (ICU) of a university hospital.We analyzed 132 lung transplants in a total of 130 patients. The patients were monitorized up to June 18, 2005 or their death.An evaluation was made of their pre-operative exercise capacity with the 6-minute walking test (6MWT). Long-term survival in relationship with the walking test value was also assessed. The survival curves were estimated using the Kaplan-Meier method. Comparison between curves was made with the Log-Rank methods and the hazard ratios were estimated by Cox regression.The association between mortality and the walking test value showed a hazard ratio of 0.99 (95% CI: 0.99-1.00) per metric unit (meter), (p = 0.282). The patients were classified according to the distance covered in the 4 groups: group 1 (distance covered less than 100 meters), group II (distance covered between 101-200 meters), group III (distance covered between 201 and 300 meters) and group IV (distance greater than 301 meters). No significant differences were found when comparing the survival curves of the four groups (p = 0.709). The multivariant analysis also did not show any statistical significance.We do not believe that the distance covered in the 6MWT conducted in the study protocol in the lung transplant candidates is useful as a marker to predict long-term mortality in patients undergoing lung transplant.

Invited commentary

Invited commentary

Influence of Preoperative Exercise Capacity on Length of Stay After Thoracic Cancer Surgery

Stress testing is frequently used to assess cardiac risk before thoracic surgery. However, the relationship between treadmill exercise capacity and length of stay (LOS) has not been investigated. We hypothesized that exercise capacity, a strong predictor of long-term prognosis, can also predict LOS after thoracic cancer surgery. Accordingly, 191 consecutive patients who had exercise stress testing before major thoracic cancer surgery were retrospectively grouped by poor (<4 metabolic equivalents [METs], n = 31), fair (4 to 7 METs, n = 107), good (7 to 10 METs, n = 30), and excellent (>10 METs, n = 23) exercise capacity. The relationship between exercise capacity and LOS was then determined. Average LOS was inversely related to exercise capacity, with a nearly twofold increase in LOS between the excellent and poor exercise groups (4.8 versus 9.2 days). This relationship remained significant even after controlling for operation type, history of dyspnea, sex, and smoking history in analysis of covariance. Prolonged hospital stay (10 days or more) was strongly predicted by exercise capacity. Failure to exceed 4 METs was associated with a high risk of prolonged stay (9 of 31, 39%), whereas none of the 23 patients who exceeded 10 METs had a prolonged stay. Treadmill exercise capacity has independent predictive value for LOS and risk of prolonged stay after thoracic cancer surgery. These findings have important implications for risk assessment and cost, suggesting that preoperative programs designed to improve exercise capacity may favorably influence LOS and associated costs.

Complications of lung resection and exercise capacity: A meta-analysis

While exercise capacity, expressed as maximal oxygen consumption (VO2max), has been proposed to be the best predictor of postoperative cardiopulmonary complications after surgical resection in lung cancer patients, the literature remains controversial. The purpose of this study was to use the meta-analytic approach to determine if VO2max, expressed as either ml kg(-1) min(-1) or as a percentage of predicted, differed between patients who develop postoperative cardiopulmonary complications versus those that do not. Studies were retrieved via (1) computerized literature searches, (2) cross referencing from retrieved articles, and (3) expert review of our reference list. Trials were included if they reported preoperative VO2max values (ml kg(-1) min(-1) or percentage of predicted) and had patients in which postoperative cardiopulmonary complications occurred. Fourteen studies representing a total of 955 men and women met our criteria for inclusion. Across all designs and categories, random-effects modeling demonstrated that patients without postoperative pulmonary complications had significantly higher levels of VO2max in ml kg(-1) min(-1) (mean difference=3.0, 95% confidence interval (CI), 1.9-4.0) as well as VO2max as a percentage of predicted (mean difference=8, 95% CI, 3.3-12.8). After a systematic review of the literature, we found that exercise capacity, expressed as VO2max, is lower in patients that develop clinically relevant complications after curative lung resection. These results are important for the practicing clinician because they answer the literature controversy on the usefulness of measuring preoperative exercise capacity and reinforce the current guidelines on decision making for lung resection.

Atrial Septal Defect in Adults: Cardiopulmonary Exercise Capacity Before and 4 Months and 10 Years After Defect Closure

Objectives. The purpose of the study was to evaluate the cardiopulmonary exercise capacity and ventilatory function in adults with atrial septal defect (ASD) preoperatively and 4 months and 10 years postoperatively.Background. Only few data are available on cardiopulmonary exercise tolerance after ASD closure, but detailed knowledge might be helpful for indication for defect closure in certain patients.Methods. The study was performed in adult patients (mean [±SD] age at operation 39.9 ± 11.5 years; left–right shunt 9.6 ± 5.6 liters/min; pulmonary/systemic flow ratio 2.8 ± 1.2; mean pulmonary artery pressure 18.2 ± 6.2 mm Hg). Cardiopulmonary exercise testing was performed with a bicycle ergometer. We determined peak oxygen uptake, anaerobic threshold, performance at anaerobic threshold and maximal performance in relation to these variables in a normal group. Ventilatory function at rest was expressed by vital capacity, maximal voluntary ventilation and forced expiratory volume in 1 s.Results. Preoperatively, ventilatory function at rest was only moderately reduced to ∼75% to 85%. Four months postoperatively we found no significant improvement, but 10 years postoperatively ventilatory function at rest was normalized. Preoperative cardiopulmonary exercise capacity was markedly reduced to 50% to 60%; early postoperatively it was only slightly higher, but late postoperatively exercise capacity significantly improved and was completely normalized.Conclusions. Although preoperative cardiopulmonary capacity in adult patients with nonrestrictive ASD was significantly decreased, some improvement was seen at 4 months postoperatively, with complete restitution to normal at 10 years after shunt closure.(J Am Coll Cardiol 1997;29:1345–50)

Prediction of post‐operative cardiopulamonary function using perfusion scintigraphy in patients with bronchogenic carcinoma

Both ventilation and perfusion scintigraphy are accurate predictors of post-operative ventilatory function. Previous attempts to predict post-operative exercise capacity after lung resection using radioisotope scintigraphy are few and results are conflicting. We studied 32 patients before and 6 months after pulmonary resection for bronchogenic carcinoma to assess the value of lung perfusion scintigraphy for the prediction of post-operative forced lung volumes and parameters on maximum exercise, including maximum ventilation and maximum oxygen uptake. Nine patients were lost to follow-up, and these patients differed from the reinvestigated patients only in the staging of the pulmonary carcinoma and not in preoperative lung function or exercise capacity. We found a clear relationship between the values predicted from a preoperative perfusion scintigraphy, spirometry and a maximum exercise study and the observed values measured 6 months post-operatively. The method underestimated the post-operative values of both spirometric and exercise measurements, especially in the higher range. Only in a few cases were the post-operative observed values less than the predicted values, and in these cases the difference was without clinical significance. Unexpected post-operative respiratory insufficiency was not observed. In conclusion, in patients in whom a pulmonary resection was performed, not only the post-operative spirometric values, but also the more functional related maximum exercise data can be predicted through the knowledge of a preoperative perfusion scintigraphy.

QRS prolongation as an indicator of risk of ischemia-related ventricular tachycardia and fibrillation induced by exercise

The majority of patients with serious ventricular arrhythmias induced by exercise have ischemic heart disease. These arrhythmias, however, develop only in a minority of the patients with coronary artery disease. The aim of this study was to investigate whether patients with ventricular tachycardia or fibrillation produced by exercise-induced ischemia exhibit any premonitory electrocardiographic indicators of arrhythmia propensity and whether arrhythmia suppression by myocardial revascularization abolished these changes. High-quality exercise electrocardiograms (50 mm/sec) from 30 case patients with ventricular tachycardia and fibrillation produced by exercise-induced ischemia were studied before and after surgical revascularization. These results were compared with those obtained from 30 control patients matched for age, sex, heart disease, and preoperative exercise capacity. The resting and peak exercise electrocardiograms were examined separately in a blinded manner with respect to QRS duration, ST-segment depression, and JT intervals. Patients with bundle branch block patterns were excluded. The QRS duration at rest was similar in case and control patients preoperatively and increased significantly with exercise in both groups. However, the QRS prolongation was larger in the group, in which it was 11 ± 3 msec compared with 4± 2 msec in the control group ( p = 0.043). QRS prolongation ≥15 msec predicted ischemia-related ventricular arrhythmias in 73% of the patients. After surgical revascularization, there was no QRS prolongation with exercise in either group. In both groups, the QRS prolongation was associated with significant ST-segment depression, which was larger in the case patients. After revascularization, the ST-segment depressios at peak xercise were smaller in both groups. The rate adaption of the JT-apex and JT-end intervals was similar in the case and control group both before and after surgery. The current findings confirm that QRS prolongation is a specific characteristic of ischemia. Furthermore, they indicate that the prolongation is greater in patients exhibiting ischemia-related ventricular tachycardia and fibrillation and that arrhythmia suppression by surgical revascularization is associated with a normalization of these changes. QRS prolongation ≥15 msec, in the absence of bundle branch block, may be a useful indicator of risk of ischemic ventricular tachycardia or fibrillation related to exercise.

Reversal of left ventricular dysfunction after aortic valve replacement for chronic aortic regurgitation: influence of duration of preoperative left ventricular dysfunction.

Preoperative left ventricular systolic function is an important predictor of postoperative prognosis in patients with aortic regurgitation. Although left ventricular dysfunction is reversible after aortic valve replacement to a greater extent in patients with good preoperative exercise capacity compared with patients with impaired exercise capacity, not all patients with preserved exercise capacity demonstrate improved left ventricular function after aortic valve replacement. To determine the influence of duration of preoperative left ventricular dysfunction on postoperative reversal of left ventricular dysfunction, we studied 37 patients with aortic regurgitation who preoperatively had left ventricular dysfunction, defined as subnormal echocardiographic fractional shortening (less than 29%), and good preoperative exercise capacity, defined as completion of stage I of the NIH treadmill protocol without limiting symptoms. Eight patients were asymptomatic. In 11 patients left ventricular dysfunction was documented 18 to 57 months preoperatively (prolonged); in 10 patients left ventricular dysfunction developed in an interval of 14 months or less preoperatively (brief); in 16 patients duration of left ventricular dysfunction was unknown. Patients with brief vs those with prolonged left ventricular dysfunction did not differ with respect to severity of preoperative symptoms or exercise tolerance, echocardiographically determined left ventricular dimensions or fractional shortening (25 +/- 3% [SD] vs 25 +/- 3%), or radionuclide angiographic ejection fraction (42 +/- 5% vs 42 +/- 5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Thrombotic obstruction of the Björk-Shiley valve: the Glasgow experience.

Thrombotic obstruction is the most feared complication of the Björk-Shiley tilting disc prosthesis. From 1971 to 1982 1186 Björk-Shiley valves were implanted in 900 patients. There were 93 deaths in hospital. Eight hundred and seven patients have been followed for a total of 4146 patient years; 14 patients were lost to follow up. Nineteen cases of thrombotic obstruction were identified at necropsy or at a repeat operation in the study group. The mitral prosthesis was thrombosed in 16 patients, the aortic in two, and the tricuspid in one. The incidence for this complication has been calculated to be 0.46 per 100 patient years for all valve positions, 0.79 for single mitral valve replacements, 0.18 for aortic replacements, and 0.63/100 for the tricuspid position. The maximum possible incidence of this complication in this population has been calculated to be 1.4 per 100 patient years. The mortality rate was 41.7% for reoperation and 63% for the development of the complication. Risk factors that have been identified are inadequate anticoagulant control, poor preoperative exercise capacity, and possibly also the implantation of small prostheses.

Exercise Capacity as a Predictor of Post-thoracotomy Morbidity1–3

Although severe impairment on routine pulmonary function tests will identify patients with a high post-thoracotomy morbidity, cardiopulmonary complications often develop in patients with only a mild-to-moderate impairment in pulmonary function. To determine whether the preoperative exercise capacity can prospectively identify those at risk of developing complications, 22 patients scheduled for thoracotomy (mean age, 55.7 +/- 2 yr) underwent an incremental exercise test on a cycle ergometer to determine their maximal O2 uptake (VO2max) prior to thoracotomy. Routine pulmonary function tests were performed and postoperative forced expiratory volume in one second (FEV1) was predicted from split function perfusion lung scan in all subjects. Eleven of the 22 patients had no cardiopulmonary complications postoperatively. The age, history of prior cardiovascular disease, degree of impairment on routine pulmonary function tests, and predicted postoperative FEV1 were similar in those who did and those who did not experience complications. However, those without complications had a significantly higher VO2max than did those who experienced complications (22.4 +/- 1.4 versus 14.9 +/- 0.9 ml/kg/min, p less than 0.001). Only 1 of 10 patients with a VO2max greater than 20 ml/kg/min had a complication, whereas all 6 patients with a VO2max less than 15 ml/kg/min had a complication. We conclude that exercise testing is a useful adjunct in the evaluation of operative risk for thoracotomy.

Preoperative exercise capacity in symptomatic patients with aortic regurgitation as a predictor of postoperative left ventricular function and long-term prognosis.

Forty-five symptomatic patients with aortic regurgitation underwent graded treadmill exercise testing before operation. Twenty-seven patients (group A) could not complete stage I of the National Institutes of Health exercise protocol because of limiting symptoms (exercise duration less than or equal to 22.5 minutes); 18 patients (group B) completed this stage without limiting symptoms (exercise duration > 22.5 minutes). Patients in group A had higher resting pulmonary capillary wedge pressures (mean 19 vs 13 mm Hg, p < 0.05) and left ventricular (LV) end-diastolic pressures (mean 24 vs 16 mm Hg, p < 0.05) than those in group B, but did not differ with respect to LV systolic dimension or fractional shortening by echocardiography or LV ejection fraction at rest or during exercise by radionuclide cineangiography. Among 32 patients with subnormal preoperative LV fractional shortening on echo, nine of 17 in group A and 0 of 15 in group B have died (p < 0.01); seven of the nine deaths were from late congestive heart failure. Group A patients also had less decrease postoperatively in LV diastolic size by echocardiography (mean decrease 8 vs 23 mm, p < 0.001) and less increase postoperatively in LV ejection fraction during exercise by radionuclide cineangiography (mean increase 11% vs 23%, p 0.05) than group B patients. No group A patient and 60% of group B patients had normal exercise ejection fractions postoperatively (p < 0.01). The differences in postoperative mortality and function were not predicted by the differences in preoperative hemodynamics between the two groups. Thus, exercise capacity is imprecise in assessing preoperative LV function in symptomatic patients with aortic regurgitation, but is useful in predicting long-term survival after operation and reversibility of LV dilatation and systolic dysfunction.