The prognostic value of exercise capacity: a review of the literature

85% of maximal age-predicted heart rate is not a valid endpoint for exercise treadmill testing

BACKGROUND

Exercise testing should be symptom-limited. Nevertheless, 40% of clinical laboratories applying for ICANL accreditation use 85% of maximal age-predicted heart rate (MPHR) as the primary exercise endpoint. We hypothesized that this approach importantly may underestimate exercise capacity and inducible ischemia.

METHODS

Two patient cohorts were studied. 1. A prospective registry of patients referred for exercise testing. 2. A retrospective cohort of patients with positive exercise ECG.

RESULTS

Of 306 registry patients, 211 (69%) continued exercising after reaching 85% MPHR to maximal HR of 101% ± 7% of MPHR. Forty-two patients (14%) stopped <1 minute after achieving 85% MPHR; 53 (17%) did not achieve 85% MPHR. More women (75%) than men (64%) achieved >85% MPHR (P = .02). Of 300 patients with positive ECG, 232 patients (77%) exercised to >85% MPHR. At 85% MPHR 144 patients (62%) had positive ECG (1.2 ± .7 mm ST depression) compared to 232 patients (100%) at peak exercise (2.3 ± .9 mm ST depression, P < .001). Mean workload at 85% MPHR was 7.3 ± 2.4 METs compared to 10.6 ± 2.8 METs at peak exercise (P < .001).

CONCLUSION

Achievement of 85% MPHR is not a valid diagnostic or functional exercise endpoint because it significantly underestimates exercise capacity and inducible ischemia.

Relative importance of comorbid psychological symptoms in patients with depressive symptoms following phase II cardiac rehabilitation

BACKGROUND

Previous research has demonstrated a high prevalence of psychological risk factors in patients with coronary heart disease (CHD), as well as the benefits of cardiac rehabilitation (CR) on psychological distress (PD) in showing its potential to improve mortality. We examined the impact of CR on mortality by anxiety and/or hostility symptoms in a large population of CHD patients with symptoms of depression following CR.

PATIENTS AND METHODS

We studied 538 patients with CHD who had completed formal CR. Using a validated questionnaire, symptoms of PD were obtained in 3 domains: anxiety, hostility, and depression. Subjects were divided into 3 groups: nondepressed (n = 502), depression alone (n = 14), and depression with anxiety and/or hostility (n = 22). A multivariate analysis for mortality was performed using a composite PD score (PD = sum of scores for anxiety, depression, and hostility). Subjects were analyzed by total mortality over 3-year follow-up by the National Death Index.

RESULTS

Mortality was significantly higher in the group with depressive symptoms compared with those without depressive symptoms (19% vs 3%; P < 0.0001). The comorbid depressed group had a slight trend toward higher mortality (22.7% [5 of 22 patients] vs 14% [2 of 14 patients]; P = 0.52). After adjusting for age, body mass index (BMI), ejection fraction, exercise tolerance, and sex using Cox proportional regression, the number of psychiatric comorbidities (ie, depression, anxiety, and hostility), as well as the sum of their raw scores, were significantly associated with increased mortality. However, this effect disappeared after adjusting for depression score (comorbidity hazard ratio, 1.7; 95% confidence interval, 1.0-2.8 vs comorbidity hazard ratio, 1.2; 95% confidence interval, 0.4-3.7 after adjusting).

CONCLUSION

Psychological distress is an independent predictor of mortality in stable CHD patients following CR; although anxiety and hostility may also modulate this effect, the overall impact seems to be mostly mediated through depression. Patients with persistent depression following CR may need further intervention.

Erythropoietin as a treatment of anemia in heart failure: systematic review of randomized trials

BACKGROUND

Anemia in heart failure is both common and associated with worse symptoms and increased mortality. Several small randomized controlled trials (RCTs) have assessed erythropoiesis-stimulating agents (ESAs), but definitive evaluation and clinical guidance are required. We sought to systematically review the effects of ESAs in chronic heart failure.

METHODS

An extensive search strategy identified 11 RCTs with 794 participants comparing any ESA with control over 2 to 12 months of follow-up. Published and additionally requested data were incorporated into a Cochrane systematic review (CD007613).

RESULTS

Nine studies were placebo controlled, and 5, double blinded. Erythropoiesis-stimulating agent treatment significantly improved exercise duration by 96.8 seconds (95% CI 5.2-188.4, P = .04) and 6-minute walk distance by 69.3 m (95% CI 17.0-121.7, P = .009) compared with control. Benefit was also noted for peak oxygen consumption (+2.29 mL/kg per minute, P = .007), New York Heart Association class (-0.73, P < .001), ejection fraction (+5.8%, P < .001), B-type natriuretic peptide (-226.99 pg/mL, P < .001), and quality-of-life indicators with a mean increase in hemoglobin level of 2 g/dL. There was a significantly lower rate of heart failure-related hospitalizations with ESA therapy (odds ratio 0.56, 95% CI 0.37-0.84, P = .005). No associated increase in adverse events or mortality (odds ratio 0.58, 95% CI 0.34-0.99, P = .047) was observed, although the number of events was limited.

CONCLUSION

Meta-analysis of small RCTs suggests that ESA treatment can improve exercise tolerance, reduce symptoms, and have benefits on clinical outcomes in anemic patients with heart failure. Confirmation requires larger, well-designed studies with careful attention to dose, attained hemoglobin level, and long-term outcomes.

Prognostic value of a nine-minute treadmill test in patients undergoing myocardial perfusion scintigraphy

Exercise capacity is an important predictor of risk in known or suspected coronary disease. A negative treadmill test to 9 minutes of the Bruce protocol is often used in the screening process for vocational licensing; myocardial perfusion scintigraphy is an alternative for those unable to exercise, with apparent incremental prognostic power above exercise testing alone. We compared exercise test and myocardial perfusion scintigraphic (MPS) findings and risk of hard cardiac events (median 4 years) in patients completing ≥ 9-minute treadmill exercise. Patients undergoing myocardial perfusion scintigraphy who completed a 9-minute Bruce protocol exercise were identified over a 2-year period. Follow-up was performed by telephone, with case-note review when necessary; this was 97% complete. Five hundred sixteen patients were identified (73% men, median age 53 year). One hundred eighty-one (35%) had known coronary disease. One hundred forty-nine (29%) had a "high-risk" exercise test result (limiting chest pain or ST-segment depression), and 69 (13%) had high-risk MPS findings (>10% myocardium ischemic or ejection fraction <40%). Of 367 patients with a reassuring exercise test result, 38 (10.4%) had high-risk MPS findings. Of 149 with a high-risk exercise test, 118 (79%) had reassuring MPS findings. At median follow-up of 49 months, there were 8 cardiac events (1.6%). Only 2 patients with high-risk exercise test results (1.4%) and 1 with high-risk MPS findings (1.5%) had an event. In conclusion, for patients able to manage a 9-minute Bruce protocol, presence/absence of symptoms or electrocardiographic changes is a poor predictor of MPS findings. Irrespective of test findings, however, subsequent cardiac risk is extremely low. Ability to complete a 9-minute Bruce protocol treadmill exercise may itself provide adequate prognostic reassurance for most purposes.

A functional polymorphism in renalase (Glu37Asp) is associated with cardiac hypertrophy, dysfunction, and ischemia: data from the heart and soul study

BACKGROUND

Renalase is a soluble enzyme that metabolizes circulating catecholamines. A common missense polymorphism in the flavin-adenine dinucleotide-binding domain of human renalase (Glu37Asp) has recently been described. The association of this polymorphism with cardiac structure, function, and ischemia has not previously been reported.

METHODS

We genotyped the rs2296545 single-nucleotide polymorphism (Glu37Asp) in 590 Caucasian individuals and performed resting and stress echocardiography. Logistic regression was used to examine the associations of the Glu37Asp polymorphism (C allele) with cardiac hypertrophy (LV mass>100 g/m2), systolic dysfunction (LVEF<50%), diastolic dysfunction, poor treadmill exercise capacity (METS<5) and inducible ischemia.

RESULTS

Compared with the 406 participants who had GG or CG genotypes, the 184 participants with the CC genotype had increased odds of left ventricular hypertrophy (OR = 1.43; 95% CI 0.99-2.06), systolic dysfunction (OR = 1.72; 95% CI 1.01-2.94), diastolic dysfunction (OR = 1.75; 95% CI 1.05-2.93), poor exercise capacity (OR = 1.61; 95% CI 1.05-2.47), and inducible ischemia (OR = 1.49, 95% CI 0.99-2.24). The Glu37Asp (CC genotype) caused a 24-fold decrease in affinity for NADH and a 2.3-fold reduction in maximal renalase enzymatic activity.

CONCLUSIONS

A functional missense polymorphism in renalase (Glu37Asp) is associated with cardiac hypertrophy, ventricular dysfunction, poor exercise capacity, and inducible ischemia in persons with stable coronary artery disease. Further studies investigating the therapeutic implications of this polymorphism should be considered.

Reducing psychosocial stress: a novel mechanism of improving survival from exercise training

BACKGROUND

Exercise training reduces mortality in patients with coronary artery disease. Behavioral characteristics, including depression, hostility, and overall psychosocial stress, have been shown to be independent risk factors for recurrent myocardial infarction and death in these patients. Exercise training can reduce these high-risk behaviors, but it remains uncertain as to what extent the health benefits of exercise training can be attributed to improving these behaviors.

METHODS

We evaluated the impact of exercise training during cardiac rehabilitation on mortality in 53 patients with coronary artery disease with high levels of psychosocial stress and in 469 patients with coronary artery disease with low levels of psychosocial stress and compared them with 27 control patients with high psychosocial stress who did not undergo formal cardiac rehabilitation and exercise training.

RESULTS

Mortality was approximately 4-fold greater in patients with high psychosocial stress than in those with low psychosocial stress (22% vs 5%; P = .003). Exercise training decreased the prevalence of psychosocial stress from 10% to 4% (P<.0001) and similarly improved peak oxygen uptake in patients with high and low psychosocial stress. Mortality in patients who improved exercise capacity by>or=10% (high exercise change) was 60% lower than in patients who had<10% improvement in exercise capacity (low exercise change) (P=.009). Mortality was lower in patients with high psychosocial stress with high exercise change compared with patients with high psychosocial stress with low exercise change (0% vs 19%; P=.009). In contrast, there was no significant improvement in mortality in patients with high versus low exercise change with low psychosocial stress (4% vs 8%; P=.14).

CONCLUSION

Psychosocial stress is an independent risk factor for mortality in patients with coronary artery disease, and exercise training can effectively reduce its prevalence. Exercise training reduces mortality in patients with coronary artery disease, and this effect seems to be mediated in part because of the salutary effects of exercise on psychosocial stress.

Achieving an exercise workload of > or = 10 metabolic equivalents predicts a very low risk of inducible ischemia: does myocardial perfusion imaging have a role?

OBJECTIVES

We sought to identify prospectively the prevalence of significant ischemia (> or =10% of the left ventricle [LV]) on exercise single-photon emission computed tomography (SPECT) imaging relative to workload achieved in consecutive patients referred for myocardial perfusion imaging (MPI).

BACKGROUND

High exercise capacity is a strong predictor of a good prognosis, and the role of MPI in patients achieving high workloads is questionable.

METHODS

Prospective analysis was performed on 1,056 consecutive patients who underwent quantitative exercise gated (99m)Tc-SPECT MPI, of whom 974 attained > or =85% of their maximum age-predicted heart rate. These patients were further divided on the basis of attained exercise workload (<7, 7 to 9, or > or =10 metabolic equivalents [METs]) and were compared for exercise test and imaging outcomes, particularly the prevalence of > or =10% LV ischemia. Individuals reaching > or =10 METs but <85% maximum age-predicted heart rate were also assessed.

RESULTS

Of these 974 subjects, 473 (48.6%) achieved > or =10 METs. This subgroup had a very low prevalence of significant ischemia (2 of 473, 0.4%). Those attaining <7 METs had an 18-fold higher prevalence (7.1%, p < 0.001). Of the 430 patients reaching > or =10 METs without exercise ST-segment depression, none had > or =10% LV ischemia. In contrast, the prevalence of > or =10% LV ischemia was highest in the patients achieving <10 METs with ST-segment depression (14 of 70, 19.4%).

CONCLUSIONS

In this referral cohort of patients with an intermediate-to-high clinical risk of coronary artery disease, achieving > or =10 METs with no ischemic ST-segment depression was associated with a 0% prevalence of significant ischemia. Elimination of MPI in such patients, who represented 31% (430 of 1,396) of all patients undergoing exercise SPECT in this laboratory, could provide substantial cost-savings.

Predictive value of heart rate recovery and peak oxygen consumption for long-term mortality in patients with coronary heart disease

Poor exercise capacity and abnormal heart rate (HR) recovery during exercise testing predict poor long-term outcomes. The relationship between these parameters in patients with coronary heart disease (CHD) is unknown. Whether abnormal HR recovery adds to the prognostic value of poor exercise capacity in patients with CHD is unclear. A total of 282 patients (17% women) with stable CHD underwent cardiopulmonary treadmill testing at the end of Phase II cardiac rehabilitation and were followed for a mean of 9.8 +/- 2.9 years. Cox proportional hazards regression with adjustment for low peak oxygen consumption ([peak VO(2)] <19 ml/kg/min for men, <15 ml/kg/min for women), age, and gender was used to test the prognostic significance of HR recovery (HR recovery = peak - 1-minute after peak HR). HR recovery and peak VO(2) correlated mildly (r = 0.35, p <0.001). Both an abnormal HR recovery (<13 beats/min) and a low peak VO(2) were significantly associated with greater mortality in a model including age, gender, low peak VO(2), and abnormal HR recovery (hazard ratio for abnormal HR recovery = 2.16, 95% confidence interval 1.14 to 4.09; hazard ratio for low peak VO(2) = 3.63, 95% confidence interval 2.09 to 6.32). Despite a preserved peak VO(2), the 10-year mortality rate was significantly greater in patients with a HR recovery of <13 beats/min compared with those with a HR recovery of >or=13 beats/min (13.6% vs 5.6%, respectively; p <0.05). In conclusion, in patients with stable CHD undergoing cardiac rehabilitation, the rate of HR recovery provides additional prognostic information beyond the peak VO(2). An abnormal HR recovery identifies a subset of patients at intermediate risk despite a preserved peak VO(2).

The joint impact of smoking and exercise capacity on clinical outcomes among women with suspected myocardial ischemia: the WISE study

BACKGROUND

Although extensive research has been conducted on both smoking and low exercise capacity alone, few studies have examined the joint impact or interaction of these two risk factors. We examined the joint and interactive effects of smoking and self-reported exercise capacity on subsequent clinical events (heart failure, myocardial infarction [MI], stroke, and cardiovascular-related mortality) among women with suspected myocardial ischemia.

METHODS

At baseline (1996-1999), 789 women completed angiographic testing of coronary artery disease (CAD) severity and provided self-report information about their smoking history and exercise capacity as well as demographic and other risk factor data. Incidence of clinical events among the women was tracked for a median of 5.9 years; this analysis was conducted in 2008.

RESULTS

In an adjusted survival analysis, women with a positive smoking history and self-reported low exercise capacity had the greatest risk of experiencing a clinical event (HR = 7.7, 95% CI 2.3, 25.5), followed by women with a positive smoking history and self-reported high exercise capacity (HR = 6.9, 95% CI 2.0, 24.6) and those with a negative smoking history and self-reported low exercise capacity (HR = 4.9, 95% CI 1.5, 15.8), relative to women with a negative smoking history and self-reported high exercise capacity. Additional analyses revealed a significant interaction between smoking history and exercise capacity, such that (1) women with a positive smoking history did not experience an additional significantly greater risk due to low exercise capacity, unlike those with a negative smoking history, and (2) all women experienced a significantly greater risk due to a positive smoking history regardless of their exercise capacity.

CONCLUSIONS

Among women with suspected myocardial ischemia, the combined protective health effects of self-reported high exercise capacity and a negative smoking history remained significant after controlling for preexisting CAD severity and other established risk factors. These findings highlight the importance of studying behavioral risk factors in combination.

Long-term mortality with multiple treadmill exercise test abnormalities: comparison between patients with and without cardiovascular disease

BACKGROUND

Poor exercise capacity, abnormal heart rate responses, and electrocardiographic abnormalities during treadmill exercise testing independently predict mortality. The combined relationship of these 3 variables to determine the incremental increase in mortality was compared in groups with and without known cardiovascular disease (CVD).

METHODS

Patients referred for treadmill exercise testing during 1986 to 1991 were included. Exercise capacity <74% (of age- and gender-predicted value), heart rate reserve of <68 beat/min, and horizontal or down-sloping ST depression of > or =1 mm were considered abnormal. Cox proportional hazards regression was used to determine all-cause mortality (average follow-up of 16 years) based on the number of exercise test abnormalities (0, 1, 2, or all 3).

RESULTS

Among 10,897 patients, 20.9% (n = 2,277) had CVD. Poor exercise capacity and limited heart rate reserve were associated with increased risk of mortality (P < .0001) in both groups; however, abnormal exercise electrocardiogram was associated with an increased risk of mortality in the no-CVD group only (P < .0001). A graded increase in mortality was observed with increase in number of abnormal exercise test results in both groups. Patients without CVD having 2 or 3 abnormal exercise test results had a similar age-adjusted risk of long-term mortality as those with CVD but normal exercise test results, with a hazard ratio comparing these groups = 1.01 (95% CI 0.79-1.28).

CONCLUSIONS

The combinatorial approach validates the prognostic significance of multiple exercise test variables. The presence of > or =2 exercise test abnormalities may constitute a "CVD risk equivalent" in patients without CVD.

Predicting survival in heart failure

Despite advances in the therapy of cardiovascular disorders, heart failure remains a challenging disease with a dismal prognosis. A plethora of variables have been shown to be related to survival in patients with heart failure. These include heart failure etiology, clinical presentation, ventricular performance, exercise capacity, neurohormones and, more recently, inflammatory and necrosis markers. In this review we briefly list established predictive markers and discuss whether survival can accurately be predicted in this condition.

Surgery in older people: an update

In the past two decades, the rate of surgery in older people has increased more rapidly than the rate of aging of the population, so both a larger proportion and a greater number of older people are now undergoing surgery. This may partly reflect a cultural change in surgery and anaesthesia with respect to a greater willingness to undertake elective procedures in older people, although there remain areas where they have less access to surgery than do younger patients. For instance, older people are less likely to undergo operative procedures after a cancer diagnosis. Furthermore, in those who do have surgery, resection rate (i.e. curative therapy) is lower than in younger people with equivalent tumour stages, and even more so in older patients with COPD, cardiovascular disease or diabetes. This article explores the complex relationship between age and surgical outcome, provides an evidence-based overview of risk assessment and common postoperative problems in older people, and summarizes good practice points (at times necessarily pragmatic) for clinical management of the older surgical patient. There has been a substantial expansion in the literature examining risks, outcomes and interventions in older surgical patients since the previous review article of this subject published in this journal. Although we do not cover anaesthesia in older people, the review of that topic remains relevant. The American Society of Anaesthesiologists' Classification of Risk which illustrates that risk is disease- rather than age- based, is shown in Table 1. Most publications examine elective rather than emergency surgery in older people (with the exception of hip fracture), and this is reflected in the content of the paper.

A pretest prognostic score to assess patients undergoing exercise or pharmacological stress testing

OBJECTIVE

A previously developed pretest score was validated to stratify patients presenting for exercise testing with suspected coronary disease according to the presence of angiographic coronary disease. Our goal was to determine how well this pretest score risk stratified patients undergoing pharmacological and exercise stress tests concerning prognostic endpoints.

DESIGN

Retrospective cohort analysis.

SETTING

University hospital stress laboratory.

PATIENTS

7452 unselected ambulatory patients with symptoms of suspected coronary disease undergoing stress testing between 1995 and 2004.

MAIN OUTCOMES MEASURES

All-cause death, cardiac death and non-fatal myocardial infarction.

RESULTS

The rate of all-cause death was 5.5% (CI 5.0 to 6.1) with 4.3 (SD 2.4) years of follow-up (Exercise 2.8% (CI 2.3 to 3.2) v Pharmacological group 11.9% (CI 10.5 to 13.3); p<0.001). The rate of cardiac death/myocardial infarction was 2.6% (CI 2.2 to 3.0) (Exercise 1.4% (CI 1.1 to 1.8) v Pharmacological group 5.3% (CI 4.3 to 6.2); p<0.001). In both groups, stratification by pretest score was significant for all-cause death and the combined endpoint. However, stratification was more effective in the pharmacological group using the combined endpoint rather than all-cause death. Pharmacological stress patients in intermediate and high risk groups were at higher risk than their respective exercise test cohorts. Referral for pharmacological stress testing was found to be an independent predictor of time to death (2.7 (CI 2.0 to 3.6); p<0.001).

CONCLUSION

A pretest score previously validated to stratify according to angiographic outcomes, effectively risk stratified pharmacological and exercise stress patients according to the combined endpoint of cardiac death/myocardial infarction.

The Prognostic Value of Normal Exercise Myocardial Perfusion Imaging and Exercise Echocardiography

OBJECTIVES

The purpose of this work was to determine the prognostic value of normal exercise myocardial perfusion imaging (MPI) tests and exercise echocardiography tests, and to determine the prognostic value of these imaging modalities in women and men.

BACKGROUND

Exercise MPI and exercise echocardiography provide prognostic information that is useful in the risk stratification of patients with suspected coronary artery disease (CAD).

METHODS

We searched the PubMed, Cochrane, and DARE databases between January 1990 and May 2005, and reviewed bibliographies of articles obtained. We included prospective cohort studies of subjects who underwent exercise MPI or exercise echocardiography for known or suspected CAD, and provided data on primary outcomes of myocardial infarction (MI) and cardiac death with at least 3 months of follow-up. Secondary outcomes (unstable angina, revascularization procedures) were abstracted if provided. Studies performed exclusively in patients with CAD were excluded.

RESULTS

The negative predictive value (NPV) for MI and cardiac death was 98.8% (95% confidence interval [CI] 98.5 to 99.0) over 36 months of follow-up for MPI, and 98.4% (95% CI 97.9 to 98.9) over 33 months for echocardiography. The corresponding annualized event rates were 0.45% per year for MPI and 0.54% per year for echocardiography. In subgroup analyses, annualized event rates were <1% for each MPI isotope, and were similar for women and men. For secondary events, MPI and echocardiography had annualized event rates of 1.25% and 0.95%, respectively.

CONCLUSIONS

Both exercise MPI and exercise echocardiography have high NPVs for primary and secondary cardiac events. The prognostic utility of both modalities is similar for both men and women.

Acute myocardial infarction after live donor liver surgery

Acute myocardial infarction is a tedious risk inherent in all major surgeries. Preoperative assessment has been directed mainly to assess its risk because it carries with it a very high mortality. Living donor liver transplantation has been subject to inquest not only because of the morbidity risk but also because of the mortality risk it carries to the live donor. We report a case of a 39-year-old donor who died of acute myocardial infarction following right-lobe donor hepatectomy. In conclusion, to our knowledge this is the first reported case of mortality due to a cardiac event following donor surgery.

"Indeterminate" microvolt T-wave alternans tests predict high risk of death or sustained ventricular arrhythmias in patients with left ventricular dysfunction

OBJECTIVES

This study tested the hypothesis that an "indeterminate" microvolt T-wave alternans (MTWA) test, when due to ectopy, unsustained MTWA, or low exercise heart rate (HR), has prognostic significance similar to a positive MTWA test.

BACKGROUND

MTWA testing, used to stratify risk of sudden or total mortality in patients with structural heart disease, has been limited by a substantial number of "indeterminate" tests. Indeterminate tests are due to patient factors--excessive ventricular ectopy during exercise, unsustained MTWA, or failure to achieve a HR of 105 beats/min for 1 min--or technical factors such as a noisy recording or an exercise protocol that causes an excessively rapid rise in HR.

METHODS

Patients in sinus rhythm with left ventricular ejection fraction < or =0.40 underwent MTWA exercise tests, analyzed with the spectral method and classified by a computerized interpretation algorithm. The primary end point was all-cause mortality or documented non-fatal sustained ventricular arrhythmia (SVA). "Indeterminate" tests were reviewed jointly by 2 readers blinded to subsequent events to determine the primary reason for indeterminacy.

RESULTS

Participants (N = 549) were 56 +/- 13 years and 71% male; 49% had ischemic cardiomyopathy. There were 40 deaths and 11 non-fatal SVA. Most (94%) indeterminate results were due to patient factors. The 2-year rate for death or SVA was 17.8% in patients with an "indeterminate" MTWA test compared with 12.3% in those with a positive test.

CONCLUSIONS

In patients with left ventricular dysfunction, an "indeterminate" MTWA test due to patient factors predicted death or SVA at least as well as a positive test.

Electrocardiographic exercise stress testing: an update beyond the ST segment

Routine exercise testing is frequently ordered to evaluate a patient's cardiovascular performance. The test is more direct and less expensive than imaging technology, and derives valuable information. New variables such as dyspnea and heart rate recovery, as well as integrated scores, provide incremental value to conventional analysis of exercise-induced angina or electrocardiographic changes. Considerations relating to test accuracy in women need to be weighed. This paper seeks to make physicians aware of the current status of the test, and improve their understanding of and ability to integrate new variables and scores to more effectively manage their patients.

Identifying which patients with diabetes should be tested for the presence of coronary artery disease – The importance of baseline electrocardiogram and exercise testing

Numerous studies have reported that diabetic patients should not always be considered to be coronary artery disease (CAD)-equivalent as was previously suggested. Exercise testing is widely available at a relatively low cost, and even among patients in whom the diagnosis of CAD is highly probable on the basis of age, sex, description of chest pain and history of prior myocardial infarction, exercise testing is often a clinical requirement for risk or prognosis assessment to determine the need for possible coronary angiography or revascularization. Nevertheless, because of either the presence of atypical symptoms or the absence of symptoms often encountered, the screening approach may differ in patients with diabetes mellitus. Because CAD is the major cause of mortality in patients with diabetes, its early detection is important to improve medical interventions and outcomes. This is critical because the available evidence suggests that occult CAD is common among asymptomatic patients with diabetes. Therefore, noninvasive testing for asymptomatic CAD may be helpful for the identification of diabetic patients with severe coronary obstruction in whom revascularization therapy may be considered the first manifestation of silent CAD in patients with diabetes is a fatal cardiac event in approximately one-half of the patients. The present paper reviews some clinical markers that may be helpful to the clinician to increase the yield of finding significant occult CAD while screening patients with diabetes.

The preoperative cardiovascular evaluation of the intermediate-risk patient: new data, changing strategies

The intermediate-risk preoperative patient can be defined as a patient without severely symptomatic or unstable heart disease who, nonetheless, has clinical predictors of adverse perioperative cardiovascular events. Newer data have created an awareness of competing considerations in managing these patients. There is still debate about how to appropriately select patients for noninvasive cardiac testing, invasive coronary testing, coronary revascularization, beta-blockers, or a combination of these. In this article, we review the evidence pertaining to these issues. We conclude that intermediate-risk preoperative patients are best managed by an approach that emphasizes the following points: intermediate-risk patients should be identified and risk stratified using a clinical tool (eg, the Revised Cardiac Risk Index); noninvasive cardiac testing should be reserved for those patients with multiple clinical predictors of risk or the presence of other modifying factors; preoperative coronary revascularization does not appear to reduce perioperative risk in patients with significant but stable coronary artery disease; and medical therapy should be optimized for these patients, including the application of beta-blockers in all intermediate-risk patients that do not have contraindications.

Influence of Induction Therapy on Rejection and Survival in Heart Transplantation

BACKGROUND AND AIMS

Immunosuppressive therapy has undergone great changes in recent years as a result of the introduction of new drugs, presumed a prior to be more effective and better tolerated. The greatest advance seems to have been the introduction of interleukin-2 (IL-2) receptor antagonists. The objective of this study was to determine whether the use of IL-2 receptor antagonists in induction therapy has implications for the development of rejection and survival.

MATERIALS AND METHODS

Three hundred sixty-five consecutive cardiac transplant patients who received induction therapy were included. Heart-lung and transplants in children under 10 years were excluded. Three groups were compared according to the induction therapy (OKT3, 10 days; OKT3, 7 days; and IL-2R antagonists). Each treatment corresponded to a time period: OKT3 10 days from June 1989 to April 1994; OKT3 7 days from May 1994 to October 2002; and IL-2R antagonists from November 2002 to May 2004. Baseline characteristics of recipient and donor, surgical times, postsurgical complications, maintenance immunosuppression, number of rejections, time (days) to first rejection, and probability of survival at 1 year were recorded. We used analysis of variance, chi(2) test, Kaplan-Meier curves, and log-rank test as appropriate. A P-value < .05 was considered significant.

RESULTS

There were significant differences in the characteristics of the transplanted patients in the various time periods. Thus, recipients in the OKT3 10 day group had worse status but better donors, whereas recipients in the IL-2R antagonists group had better status but older donors with longer duration of ischemia. The incidence of acute graft failure was similar in the three groups. The number of rejection episodes in the first year was higher among the OKT3 groups (OKT3 10 days, 1.7 +/- 1.3; OKT3 7 days, 1.2 +/- 1.2; IL-2R antagonists, 1.0 +/- 1.2; P = .02) and the probability of survival at 1 year was also lower (OKT3 10 days, 74%; OKT3 7 days, 77%; IL-2R antagonists, 94%; P = .0007).

CONCLUSIONS

Induction therapy with IL-2 antagonists offers important advantages over treatment with OKT3 in terms of survival, with absolute and relative risk reductions of 20% and 27%. Furthermore, it did not increase the number of rejections, although this may have been due to the greater use of MMF versus azathioprine.

Exercise duration and peak systolic blood pressure are predictive of mortality in ambulatory patients with mild-moderate chronic heart failure

BACKGROUND AND AIMS

It is a prevailing concept in chronic heart failure (CHF) that ventricular remodelling (evaluated via imaging) and neurohormonal activation (via biomarkers) exert major influences, such that the need to subject patients to haemodynamic evaluations and exercise testing has been questioned. We sought to investigate whether exercise and haemodynamic parameters lack independent prognostic value in a cohort of unselected ambulatory patients with mild-moderate CHF.

METHODS

Eighty-five consecutive patients with stable CHF in New York Heart Association functional classes I-IV, aged 55 +/- 12 years, 84% males, left ventricular ejection fraction (LVEF) 37 +/- 15%, participated in this study. Survivors were followed for a median of 5.08 years. All subjects underwent cardiopulmonary exercise testing to measure standard parameters including peak oxygen consumption, exercise duration and blood pressure. A sample of venous blood was taken to determine the N-terminal pro-brain natriuretic peptide (N-BNP) level. Echocardiography was performed at rest to measure LVEF. Predictors of mortality were sought using the Cox proportional hazards model.

RESULTS

All-cause mortality was 19% (16 deaths, 95% CI 11-29%). Age and LVEF did not independently predict mortality. Although various parameters including New York Heart Association class, peak oxygen consumption and N-BNP level were all predictive of outcome on univariate analysis, multivariate analysis identified reduced exercise duration and peak systolic blood pressure (SBP) to be the only independent predictors of all-cause mortality. Hazard ratios of 0.78 (95% CI 0.65-0.93, p = 0.007) and 0.79 (95% CI 0.66-0.95, p = 0.01) were associated with an increase in exercise duration of 1 min and 10 mm Hg peak SBP, respectively.

CONCLUSIONS

Two simple parameters (exercise duration and peak SBP) that are easily measured by standard exercise testing are the strongest independent predictors of mortality which outperform LVEF and N-BNP in ambulatory patients with mild-moderate CHF.

Exercise capacity and cardiovascular adaptations to aerobic training early after stroke

Clinicians are becoming increasingly interested in the use of aerobic training to enhance functional outcomes after stroke. Several studies have demonstrated the effectiveness of training among individuals in the chronic poststroke period. However, there is limited information on the response to training in earlier stages of recovery. The purpose of this article is to review what is known regarding the capacity of people early after stroke (<4 months) to respond to the physiological demands of exercise (exercise capacity) as well as their ability to make long-term cardiovascular adaptations to aerobic exercise. There is evidence that exercise capacity, as measured by peak oxygen consumption on maximal exercise tests, is reduced in this population. There is also evidence, albeit limited, that exercise trainability soon after stroke can be both feasible and safe, if appropriate screening and monitoring are used. Moreover, there are early indications that activity-level functions such as walking speed, mobility, and balance may be enhanced through such programs. Further research is necessary to elucidate the most appropriate timing and design of fitness programs for people early after stroke.

Relationship of Serum Cardiac Markers following Successful Percutaneous Coronary Intervention and Subsequent Exercise Capacity in Patients with Chronic Stable Angina: A Pilot Study

We performed a pilot study to assess the significance of modest, asymptomatic, elevated serum cardiac markers--troponin T (TnT) and creatinine kinase-MB (CK-MB)--18-24 h following successful elective percutaneous coronary intervention (PCI) and to explore their relationship with changes in aerobic exercise capacity, as measured by peak oxygen consumption (VO2), 6 weeks following the procedure. Twenty-three patients with single-vessel disease and chronic angina performed an incremental cardiopulmonary exercise test before and 6 weeks after successful uncomplicated PCI. A venous blood sample was taken at rest before PCI and 18-24 h after the procedure. Successful PCI resulted in a trend towards an increased peak VO2 [21.62 +/- 0.64 (pre) vs. 23.03 +/- 0.75 ml/ kg/min (post), p = 0.07; mean +/- SEM]. There was a significant increase [median (IQR)] in TnT, from 0.00 (0.00) microg/l at baseline increasing to 0.02 (0.03) microg/l at 18-24 h, p = 0.002. CK-MB levels showed no significant difference. In the group of 15/23 (65%) patients with an elevation in serum TnT (>/=0.01 microg/l), 18-24 h after successful PCI, there was no significant increase in peak VO2 [23.31 +/- 0.96 (pre) vs. 23.89 +/- 1.09 ml/kg/min (post), p = 0.57]. In 8 (35%) patients with no rise in TnT at 18-24 h, a significant increase in peak VO2 was observed following successful PCI [23.10 +/- 0.91 (pre) vs. 25.09 +/- 0.75 ml/kg/min (post), p = 0.02]. Although 7 of these 8 patients increased their peak VO2, the absence of a TnT rise at 18-24 h was not significantly associated with an increase in peak VO2 following successful PCI (p = 0.18). To confirm these interesting initial results and investigate the relationship of serum cardiac markers following successful PCI and subsequent exercise capacity, further studies are required.

Exercise capacity in adult African-Americans referred for exercise stress testing: is fitness affected by race?

STUDY OBJECTIVES

To determine the factors associated with exercise capacity.

DESIGN

Retrospective evaluation of large stress-testing database.

SETTING

Multispecialty tertiary care center.

PATIENTS

A total of 5,069 consecutive patients who were referred for exercise stress testing.

MEASUREMENTS

We compared levels of fitness in 641 African-Americans (52% male) with 4,428 whites (73% male), and performed univariate and multivariate analyses to determine the predictors of fitness (including race).

RESULTS

Compared with African-American men (mean [+/- SD] age, 60 +/- 11 years), white men (mean age, 63 +/- 11 years) have significantly higher exercise capacity (10.7 +/- 3.5 vs 11.4 +/- 3.4 metabolic equivalents [METs], respectively; p < 0.001). The exercise capacity in African-American and white women was similar (8.5 +/- 2.9 vs 8.7 +/- 3.0 METs, respectively). However, body mass indexes (BMIs) were significantly higher in both African-American men (29.1 +/- 4.3 vs 28.2 +/- 4.3 kg/m(2), respectively; p < 0.001) and women (30.2 +/- 5.7 vs 27.9 +/- 5.5 kg/m(2), respectively; p < 0.0001) compared to their white counterparts, as was the prevalence of obesity (men, 44% vs 33%, respectively; women, 37% vs 27%, respectively; both p < 0.001). Although a model containing age, gender, BMI, and race only accounted for 32% of exercise capacity, all independently (p < 0.0001) predicted higher exercise capacity, as follows: younger age (r(2) = 0.14); male gender (r(2) = 0.12); BMI (r(2) = 0.06); and white race (r(2) = 0.004).

CONCLUSIONS

In an adult population of individuals who were referred for exercise stress testing, African-Americans were more obese and had significantly lower exercise capacity than their white counterparts. Emphasis on weight reduction and increasing physical fitness is particularly needed for the prevention of cardiovascular diseases in African-Americans.

Longitudinal changes in exercise capacity after stroke

OBJECTIVE

To determine if stroke patients without specific aerobic training experience a change in the first 6 months after stroke.

DESIGN

Descriptive, longitudinal study with repeated measures of exercise capacity at 1, 2, 3, and 6 months after stroke.

SETTING

Exercise testing laboratory in a tertiary care hospital.

PARTICIPANTS

Consecutive sample of 25 patients (mean age +/- standard deviation, 64.1+/-13.6 y) 1 month after first ischemic stroke.

INTERVENTIONS

Not applicable. Main Outcome Measures Peak oxygen consumption (Vo(2)peak) was measured by open-circuit spirometry during maximal effort treadmill walking with 15% body-weight support.

RESULTS

Mean Vo(2)peak increased from 14.8+/-5.3 mL x kg(-1). min(-1) at 1 month to 17.3+/-7.0 mL x kg(-1).min(-1) at 6 months after stroke (P=.003) or from 61.7%+/-16% to 71.3%+/-23% of age- and sex-related normative values for sedentary healthy adults (P=.008).

CONCLUSIONS

Despite improvements in Vo(2)peak and other indices of cardiovascular training between 1 and 6 months poststroke, substantial limitations in exercise capacity persisted. Further study is needed to determine the extent to which these limitations can be modified through aerobic conditioning.

Non-alcoholic fatty liver disease, non-alcoholic steatohepatitis and orthotopic liver transplantation

Obesity, non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are becoming increasingly common medical problems in the developed world, often in the setting of the metabolic or insulin resistance syndrome (IRS). It is predicted that by the year 2025 > 25 million Americans may have NASH-related liver disease. NASH and NAFLD also affect the donor population. The use of steatotic donor livers for liver transplantation (LT) is associated with an increased risk of primary nonfunction (PNF) in the allograft. There is particular reluctance to use steatotic livers for living donor LT. There is indirect evidence to suggest that patients undergoing LT for cirrhosis resulting from NASH may have poorer outcome, despite careful selection of LT candidates. Indeed it is likely that many potential LT candidates with NASH are excluded from LT due to co-morbid conditions related to IRS. The post-LT patient is at risk of several components of IRS, such as diabetes mellitus, hypertension, hyperlipidaemia and obesity and there is increasing recognition of de novo and recurrent NAFLD and NASH after LT. Thus NAFLD and NASH affect all aspects of LT including donors, patients in evaluation and the LT recipient.

The role of cardiopulmonary exercise test in mitral and aortic regurgitation: it can predict post-operative results

BACKGROUND

We evaluated the efficacy of the cardiopulmonary exercise test as an objective indicator of functional status and as a pre-operative prognostic indicator in patients with mitral regurgitation (MR) and aortic regurgitation (AR).

METHODS

Cardiopulmonary exercise tests and echocardiography were performed in 47 patients (MR: 30, AR: 15, MR + AR: 2) before surgery and repeated one year after surgery. We compared the New York Heart Association (NYHA) functional class, peak oxygen consumption rate (VO2peak), exercise duration, left ventricular dimension and ejection fraction, before and after surgery.

RESULTS

Initial VO2peak and exercise duration were significantly different according to NYHA class. A year later, NYHA functional class improved from 2.1 +/- 0.1 to 1.4 +/- 0.1 (p < 0.001). The VO2peak was significantly increased (21.7 +/- 1.0 to 23.7 +/- 1.0 mL/kg per min, p = 0.008) and exercise duration also increased (521.7 +/- 35.9 to 623.3 +/- 35.7 seconds, p < 0.001). When patients were analysed according to their post-operative NYHA functional class, those with class I showed significantly different pre-operative VO2peak (class I: 23.7 +/- 1.1, II: 18.3 +/- 1.5 mL/kg per min, p = 0.005) and exercise durations (class I: 587.5 +/- 43.2, II: 415.6 +/- 55.7 seconds, p = 0.02). Patients with higher pre-operative VO2peak (19.0 mL/kg per min) more frequently became NYHA functional class I than those with a lower pre-operative VO2peak (76.7% vs. 35.3%, p = 0.02). But baseline left ventricular dimension and ejection fraction by echocardiography were not different between post-operative class I and II group.

CONCLUSION

VO2peak and exercise duration are excellent parameters to evaluate the subjective functional class and to predict the post-operative functional class of patients with MR and/or AR. Patients with a pre-operative VO2peak of 19.0 mL/kg per min or more will have a better functional status one year after surgery.

[Clinical predictors of the presence of perfusion defects in more than than one territory in myocardial scintigraphy with GATED-SPECT]

BACKGROUND AND OBJECTIVE

Extension of perfusion defects is associated with outcome in patients undergoing myocardial scintigraphy. The study aimed to identify the clinical characteristics that can predict the existence of perfusion defects in more than one territory in patients referred for myocardial scintigraphy with GATED-SPECT.

PATIENTS AND METHODS

A total of 193 patients undergoing myocardial scintigraphy with GATED-SPECT (99mTc-tetrofosmine) were studied. Clinical variables and scintigraphy results were studied to determine what clinical variables are associated with perfusion defects in more than one territory.

RESULTS

The number of territories with perfusion defects per patient was 1.1 0.8 and 29% had perfusion defects in > 1 territory. Patients with greater probability of having perfusion defects in > 1 territory were those with previous myocardial infarction (44% vs 21%, p = 0.030) and males (33% vs 10%, p = 0.006). In addition, patients with > 2 coronary risk factors had a statistical tendency to have defects in > 1 territory (47% vs 20%, p = 0.057). Only 15% of the patients with one of these three characteristics had perfusion defects in > 1 territory in comparison with 45% and 83% in those with 2 or 3 factors, respectively.

CONCLUSION

Considering 3 simple clinical characteristics (male gender, previous infarction and existence of > 2 coronary risk factors), it is possible to predict which patients are more likely to show perfusion defects in > 1 territory during GATED-SPECT myocardial scintigraphy.

Exercise capacity early after stroke

OBJECTIVE

To evaluate exercise capacity of patients with a poststroke interval of less than 1 month.

DESIGN

Prospective, cohort, observational study.

SETTING

Exercise testing laboratory in a tertiary care hospital.

PARTICIPANTS

Twenty-nine patients (mean age +/- standard deviation, 64.9+/-13.5 y) with a poststroke interval of 26.0+/-8.8 days.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Peak exercise capacity (VO(2)peak) was measured by open-circuit spirometry during maximal effort treadmill walking with 15% body-weight support.

RESULTS

Mean VO(2)peak was 14.4+/-5.1 mL. kg(-1). min(-1) or 60%+/-16% of age- and sex-related normative values for sedentary healthy adults.

CONCLUSIONS

Exercise capacity approximately 1 month after stroke was compromised. Further research is needed to elucidate the physiologic basis of this low capacity.

Prediction of long-term prognosis in 12 169 men referred for cardiac rehabilitation

BACKGROUND

Predicting the risk of cardiac and all-cause death in patients with established coronary heart disease is important in counseling the individual and designing risk-stratified rehabilitation and secondary prevention programs. Cox proportional hazards and Kaplan-Meier survival curves were thus completed on initial assessment data obtained from patients referred to an outpatient cardiac rehabilitation center.

METHODS AND RESULTS

A single-center prospective observational design took peak cardiorespiratory exercise test data for 12 169 male rehabilitation candidates aged 55.0+/-9.6 years (7096 myocardial infarctions [MIs], 3077 coronary artery bypass grafts [CABGs], and 1996 documented cases of ischemic heart disease [IHD]). A follow-up of 4 to 29 years (median, 7.9) yielded 107 698 man-years of experience. Entry data were tested for associations with time to cardiac and all-cause death. We recorded 1336 cardiac deaths (953 MI, 225 CABG, and 158 IHD) and 2352 all-cause deaths. A powerful predictor of cardiac and all-cause mortality was measured peak oxygen intake (VO2peak). For the overall sample, values of <15, 15 to 22, and >22 mL/kg per minute yielded respective multivariate adjusted hazard ratios of 1.00, 0.62, and 0.39 for cardiac and 1.00, 0.66, and 0.45 for all-cause deaths. For the separate diagnostic categories, apart from VO2peak, the only other significant predictors of cardiac death common to all 3 were smoking and digoxin, and for all-cause death, age, smoking, digoxin, and diabetes.

CONCLUSIONS

Exercise capacity, as determined by direct measurement of VO2peak, exerts a major long-term influence on prognosis in men after MI, CABG, or IHD and can play a valuable role in risk stratification and counseling.

Perioperative management of the hospitalized patient

The hospitalized surgical patient requires a team approach. Because of increasing patient age and complexity of conditions, a comprehensive preoperative evaluation and medical optimization is often necessary to allow the anesthesiologist and surgeon to deliver the best surgical outcome. Surgical patients at an increased risk for postoperative complications should be followed carefully by a medical consultant throughout the hospital stay. This continuity of perioperative care improves the likelihood that postoperative problems, such as delirium, early myocardial ischemia, or VTE, are quickly identified, and appropriate therapeutic interventions are initiated before more serious adverse events occur. Special surgical populations, such as those patients who need perioperative anticoagulation, further benefit from a surgical team that includes a medical specialist. Expertise and close supervision throughout the perioperative period will give the hospitalized surgical patient the greatest chance for a quick and successful recovery.

Surrogate end points in heart failure

Because of the increasing number of pharmacologic strategies available for treatment of heart failure (HF), the time has come to reassess the adequacy of end points used to evaluate therapeutic efficacy. Interest in the use of surrogate end points in clinical studies is increasing. A surrogate end point is defined as a measurement that can substitute for a true end point for the purpose of comparing specific interventions or treatments in a clinical trial. A true end point is one that is of clinical importance to the patient (e.g., mortality or quality of life), whereas a surrogate end point is one biologically closer to the disease process (e.g., ejection fraction or left ventricular volume in HF). The prime motivation for the use of a surrogate end point concerns the possible reduction in sample size or trial duration. Such reductions have important cost implications and in some cases may influence trial feasibility. Another, perhaps more important, aspect of measuring surrogate end points is that they increase our understanding of the mechanism of action of drugs and thus may help physicians to take a more enlightened approach in managing their patients. In this article we have analyzed the possible potentials of the surrogate end points in clinical studies of patients with chronic HF. Other uses of possible surrogates are discussed, and the limitations in finding true surrogates are mentioned. At this time we conclude there is no well established surrogate in HF.