Simple treadmill score to diagnose coronary disease

The diagnostic utility of the basal and post-exercise QRS-T angle in patients with stable coronary artery disease

BACKGROUND

To evaluate the diagnostic utility of basal and post-exercise QRS-T angle in patients with stable coronary artery disease (CAD).

METHODS

This cross-sectional and observational study analyzed 190 patients with stable angina. The QRS-T angle is measured on the 12-lead electrocardiograms at baseline and just after stopping the treadmill stress test in patients undergoing conventional coronary angiography (CAG). The pre- and post-exercise QRS-T angle and ΔQRS-T angle were analyzed.

RESULTS

Of the 190 patients, 66 (34.7%) were assigned to group 1 (patients with coronary lesion) and 124 (65.3%) to group 2 (patients without coronary lesion) after CAG. There was no statistically significant difference in QRS-T angle between groups at baseline (pre-exercise) (30.7 ± 17 vs. 27.8 ± 12.8, p = .233). The QRS-T angle value was significantly higher in group 1 than in group 2 (68.8 ± 40.3 vs. 22.7 ± 21.5, p = .01) after exercise (post-exercise). The ΔQRS-T angle was also significantly higher in group 1 than in group 2 (38.1 ± 37.6 vs. -5.1 ± 22.9, p = .01). Receiver operating characteristic curve revealed that the cut-off value of QRS-T angle (post-exercise) for the coronary obstruction was >51.5° with 81% of sensitivity and 66% of specificity (AUC: 0.832, p = .001, CI: 0.769-0.894). Duke treadmill score for coronary stenosis was >1.5 with 77% of sensitivity and 69% of specificity (AUC: 0.814, p = .001, CI: 0.749-0.878).

CONCLUSION

It could be proposed that post-exercise QRS-T angle and Δ QRS-T angle are significantly associated with coronary obstruction in patients with stable angina and appear to be more sensitive than the Duke treadmill score and traditional electrocardiographic parameters.

PCI Alternative Using Sustained Exercise (PAUSE): Rationale and trial design

Cardiovascular disease (CVD) currently claims nearly one million lives yearly in the US, accounting for nearly 40% of all deaths. Coronary artery disease (CAD) accounts for the largest number of these deaths. While efforts aimed at treating CAD in recent decades have concentrated on surgical and catheter-based interventions, limited resources have been directed toward prevention and rehabilitation. CAD is commonly treated using percutaneous coronary intervention (PCI), and this treatment has increased exponentially since its adoption over three decades ago. Recent questions have been raised regarding the cost-effectiveness of PCI, the extent to which PCI is overused, and whether selected patients may benefit from optimal medical therapy in lieu of PCI. One alternative therapy that has been shown to improve outcomes in CAD is exercise therapy; exercise programs have been shown to have numerous physiological benefits, and a growing number of studies have demonstrated reductions in mortality. Given the high volume of PCI, its high cost, its lack of effect on survival and the potential for alternative treatments including exercise, the current study is termed "PCI Alternative Using Sustained Exercise" (PAUSE). The primary aim of PAUSE is to determine whether patients randomized to exercise and lifestyle intervention have greater improvement in coronary function and anatomy compared to those randomized to PCI. Coronary function and anatomy is determined using positron emission tomography combined with computed tomographic angiography (PET/CTA). Our objective is to demonstrate the utility of a non-invasive technology to document the efficacy of exercise as an alternative treatment strategy to PCI.

Prognostic value of electrocardiogram exercise testing for risk stratification in asymptomatic coronary artery disease

BACKGROUND

Several variables of electrocardiogram exercise testing (EET) predict cardiovascular events in the general population and in patients with coronary artery disease (CAD). However, most of the studies have not included patients with asymptomatic CAD. The aim of this study was to evaluate the prognostic value of EET in asymptomatic CAD patients.

PATIENTS AND METHODS

We carried out a retrospective single-center analysis including all patients with asymptomatic CAD documented by angiography who underwent EET from January 2010 to December 2013. A number of EET variables and three exercise scores [Duke Treadmill Score (DTS), Morise score, and FIT score] were analyzed. The primary endpoint was the combined incidence of myocardial infarction (MI), myocardial revascularization, and death from any cause during follow-up.

RESULTS

A total of 306 patients were included (mean age was 65±10 years, 61% had previous MI, and the median exercise capacity was 9.4±2.7 metabolic equivalent of task). The primary endpoint occurred in 15.7% of patients during 3.3 years of follow-up. The DTS and FIT were independent predictors of the primary endpoint unlike the Morise score (DTS: hazard ratio=0.91, 95% confidence interval: 0.85-0.99, P=0.018; FIT score: 0.99, 0.98-0.996, P=0.001; Morise score: 0.97, 0.93-1.02, P=0.20). The DTS was independent predictor of MI or revascularization, whereas FIT predicted death from any cause. Excluding patients with early revascularization, DTS had no predictive power at the composite endpoint.

CONCLUSION

In our population with asymptomatic CAD, FIT and DTS had significant value for risk prediction and consequently the EET can be a valid tool in the clinical follow-up of this population.

Hemoglobin levels predict exercise performance, ST-segment depression, and outcome in patients referred for routine exercise treadmill testing

BACKGROUND

While the role of hemoglobin in heart failure and renal disease has been investigated, little is known about its effect on clinical exercise test performance and mortality in patients referred for routine exercise treadmill testing (ETT).

HYPOTHESIS

Patients with low hemoglobin will have poor exercise capacity and would be at increased risk of mortality and cardiovascular (CV) events.

METHODS

Clinical variables, laboratory values, and exercise treadmill data were obtained for 1,799 patients referred for routine ETT from 1997 to 2004. All-cause mortality was obtained from the United States Social Security death index and autopsy reports or clinical notes were used to determine CV events and mortality. P values < 0.05 were considered significant.

RESULTS

Our population had a mean age of 58 +/- 12 years, 16% had diabetes, 53% had hypertension, 35% had hypercholesterolemia, and 67% had a history of smoking. During follow-up, 10.3% of patients died, 3.9% of patients died of CV causes, and 11.6% had cardiovascular events. Anemic patients (hemoglobin [Hgb] < 13 g/dL) achieved lower metabolic equivalents (METs) than nonanemic patients and had more ST-segment depression (15.5% versus 8.6%, p < 0.004). Proportional hazard analysis demonstrated that hemoglobin was significantly associated with all-cause mortality (p < 0.0007), CV mortality (p < 0.009), and CV events (p < 0.01). Kaplan-Meier survival analysis demonstrated that anemic patients had significantly higher mortality and CV events.

CONCLUSION

Hemoglobin is significantly associated with exercise performance, ST-segment depression during ETT, mortality, and cardiovascular events. The incorporation of hemoglobin may add diagnostic and prognostic information to ETT.

What percent luminal stenosis should be used to define angiographic coronary artery disease for noninvasive test evaluation?

BACKGROUND

There has been controversy over what is the best angiographic luminal dimension criterion associated with ischemia for evaluating diagnostic tests. If one assumes that ST-segment depression or scores are indicators of ischemia, then whatever angiographic criteria best discriminates those with ischemic and nonischemic responses would be the best angiographic marker for ischemia. To study this, we calculated the area under the ROC curves for ST depression and scores at different angiographic cut-points in order to determine the best angiographic cut-point for defining ischemia-producing coronary disease.

METHODS

Twelve hundred and seventy-six consecutive males without prior MI with a mean age of 59 +/- 11 years who had undergone exercise testing and coronary angiography were analyzed in this study. We calculated the number of patients of this population that would be considered to have coronary artery disease at different cut-points for angiographic luminal stenosis. For example, 59% of the patients had significant CAD when disease was defined as 50% or greater coronary lumen stenosis of any coronary vessel while 49% of the patients had significant CAD when disease was defined as 70% or greater coronary lumen stenosis. Cut-points were considered between 40 to 100% coronary lumen stenosis. ROC analysis was then performed comparing ST depression and treadmill scores at each of these cut-points.

RESULTS

The cut-point for coronary lumen stenosis that returned the highest AUC for ST depression and scores was between 70 and 80% coronary luminal stenosis. However, the difference between the 50% and 75% luminal stenosis criteria was minimal.

CONCLUSION

It appears that the best cut-point for defining significant angiographic disease when evaluating diagnostic tests of ischemia is 75% or greater coronary luminal stenosis.

Stress testing in the medical evaluation for hazardous materials duty: results and consequences in three groups of candidates

OBJECTIVE

The objective of this study was to determine the yield of exercise stress testing (GXT) and other methods for evaluating candidates for HAZMAT duty.

METHODS

The authors conducted an analysis of prior and current records of GXTs, medical examinations, blood tests, chest radiographs, spirometry, and audiometry in 190 candidates. The authors also conducted scrutiny of GXT results, using Duke Treadmill Score (DTS), Chronotropic Index (CI), and Heart Rate Recovery (HRR).

RESULTS

Seven candidates were disapproved by history and/or physical examination. Twenty-one others were deferred for GXT-induced, marked hypertension, and/or ST depression >/=2 mm. The latter appeared to be false-positive indications of ischemia, low risks confirmed by DTS, CI, and HRR. Heat stress was not induced in 26 subjects so evaluated.

CONCLUSIONS

GXT identified marked hypertension in 12 HAZMAT candidates and ischemic ST changes in 10, the latter appearing to be false-positives. Other testing yielded useful baselines, rarely disqualifying.

Determining the need for coronary revascularization by an exercise test assessment computer program (ETAP)

The rate at which coronary artery revascularization procedures are performed remains inconsistent, and their risks may be greater and long-term benefits less than imagined by the general public and open to considerable inter-individual variation. However, these risks and benefits can be explicitly estimated for an individual patient from a brief medical history and the results of a standard exercise test by a computer program that uses conventional medical decision making techniques. The program first estimates the prior and post-exercise test probability of coronary artery disease and then employs a decision analysis model to define the risks and benefits associated with different treatment options. These results are provided in a printed report that can become part of the clinical record to be reviewed with the patient. In contrast with traditional clinical intuition, the program consistently and explicitly defines the risks and benefits of coronary artery disease treatments. The program forces physicians and their patients to appraise critically the information and beliefs upon which they base their clinical decisions.

Effect of Age and End Point on the Prognostic Value of the Exercise Test

BACKGROUND

The clinical and exercise test variables chosen for predicting prognosis vary in the available studies. This could be due to the effect of age of the patients tested and the choice of outcomes used as end points in these follow-up studies.

OBJECTIVE

To evaluate the effect of age and end points on exercise test variables chosen as significantly and independently associated with time to death.

METHODS

Analyses were performed on the first treadmill test performed on consecutive male veterans at the Palo Alto and Long Beach Veterans Affairs Medical Centers since 1987. After removal of patients with congestive heart failure, coronary interventions, left bundle-branch block, atrial fibrillation, myocardial infarction and/or Q wave, and digoxin use, 3,745 male subjects remained. The outcomes were cardiovascular and all-cause mortality. The study population was divided into subsets according to age; exercise test and clinical variables were analyzed within the age subsets using the Cox hazard model.

RESULTS

The mean age at the time of testing was 57 +/- 12 years (+/- SD) and they were followed up for a mean of 6.6 years. There were 544 all-cause deaths, with 206 of the deaths being due to cardiovascular causes (38%). When the study group was classified into subsets based on age, exercise capacity (in metabolic equivalents [METs]) was chosen by the Cox hazard model most consistently in the age groups using either end point. Even when age was added to the Duke treadmill score, prediction of death did not improve in those > 70 years of age because of the nonlinear relationship between age, the exercise test variables, and time to death. The most important age cut points for clinically important differences in exercise test predictors appeared to be 70 years and 75 years of age. In the patients 70 to 75 years of age, peak METs was the only variable predictive of all-cause mortality, and exercise-induced ST-segment depression was the only predictor of cardiovascular death; in the patients > 75 years of age, none of the exercise test responses were predictive of either death outcome.

CONCLUSION

Both age and the outcome selected as an end point affect the exercise test responses chosen for scores to predict prognosis. Differences in age of the subjects tested and/or the outcome selected as the end point can explain the differences in the studies using exercise testing to predict prognosis.

Treadmill scores in elderly men

OBJECTIVES

This study seeks to further characterize the role of exercise testing in the elderly for prognosis and diagnosis of coronary artery disease.

BACKGROUND

Recent exercise testing guidelines have recognized that statements regarding the elderly do not have an adequate evidence-based quality because the studies they are based on have limitations in sample size and design. The Duke Treadmill Score has been recommended for risk stratification, but recent evidence has suggested that it does not function in the elderly.

METHODS

The study population consisted of male veterans (1872 patients >or=65 years; 3798 patients <65 years) who underwent routine clinical exercise testing with a mean follow-up of six years. A subset who underwent coronary angiography as clinically indicated (elderly, n = 405; younger, n= 809) were included. The primary outcome for all subjects was cardiovascular mortality with coronary angiographic findings as the outcome in those selected for angiography.

RESULTS

In survival analysis, exercise-induced ST depression was prognostic in both age groups only when cardiovascular death was considered as the end point. Peak metabolic equivalents were the most significant predictor for both age groups only when all-cause death was considered as the end point. New age-specific prognostic scores were developed and found to be predictive for cardiovascular mortality in the elderly. Moreover, in the angiographic subset of the elderly, a specific diagnostic score provided significantly better discrimination than exercise ST measurements alone. For any new score, there is a need for validation in another elderly population.

CONCLUSIONS

The mortality end point affected the choice of prognostic variables. This study demonstrates that exercise test scores can be helpful for the diagnosis and prognosis of coronary disease in the elderly.

Evaluation of pretest and exercise test scores to assess all-cause mortality in unselected patients presenting for exercise testing with symptoms of suspected coronary artery disease

OBJECTIVES

To determine how well recently developed multivariables scores assess for all-cause mortality in patients with suspected coronary disease presenting for exercise electrocardiography (ExECG).

BACKGROUND

Recently revised American College of Cardiology/American Heart Association guidelines for ExECG have suggested that ExECG scores be used to assist in management decisions in patients with suspected coronary artery disease. Recently developed scores accurately stratify patients according to angiographic disease severity.

METHODS

To determine how well these scores assess for all-cause mortality, we utilized 4,640 patients without known coronary disease who underwent ExECG to evaluate symptoms of suspected coronary disease between 1995 and 2001. Previously validated pretest and exercise test scores as well as the Duke treadmill score were applied to each patient. All-cause mortality was our end point.

RESULTS

Overall mortality was 3.0% with 2.8 +/- 1.6 years of follow-up. All three scores stratified patients into low-, intermediate-, and high-risk groups (p < 0.00001). No differences were seen when patients were evaluated as subgroups according to gender, diabetes, beta-blockers, or inpatient status. Low-risk patients defined by the Duke treadmill score had consistently higher mortality and absolute number of deaths compared with low-risk patients using other scores. In addition, the Duke treadmill score had less incremental stratifying value than the new exercise score.

CONCLUSIONS

Simple pretest and exercise scores risk-stratified patients with suspected coronary disease in accordance with published guidelines and better than the Duke treadmill score. These results extend to diabetics, inpatients, women, and patients on beta-blockers.

Development and validation of a simple exercise test score for use in women with symptoms of suspected coronary artery disease

BACKGROUND

Recently revised American College of Cardiology/American Heart Association guidelines for exercise electrocardiography (ExECG) have suggested that ExECG scores be used to assist in management decisions in patients with suspected coronary artery disease (CAD).

METHODS

We used 442 women who underwent both ExECG and coronary angiography (CAD > or =1 lesion with > or =50% stenosis; CAD prevalence was 32%) to derive an ExECG score including clinical and ExECG variables. By use of logistic regression analysis, variables were selected and relative weights were determined. Variable codes multiplied by respective weights were summed to produce a final ExECG score. The score was validated in separate populations concerning angiographic as well as prognostic end points.

RESULTS

Clinical variables selected and their weights included age (5), symptoms (2), diabetes (2), smoking (2), and estrogen status (1). ExECG variables selected and their weights included ST depression (2), exercise heart rate (4), and Duke Angina Index (3). For the validation group, score ranges are shown with the prevalence of CAD: <20 = 0/5 or 0%, 20-29 = 3/26 or 11%, 30-39 = 20/56 or 36%, 40-49 = 33/81 or 41%, 50-59 = 24/49 or 49%, 60-69 = 22/32 or 69%, and >70 = 7/7 or 100%. Frequency of death within 3 predetermined subgroups was as follows: low <40 = 3/1237 (0.2%), intermediate 40-60 = 9/383 (2.3%), high >60 = 4/54(7%); P<.0001.

CONCLUSION

A simple ExECG score was developed for use specifically in women. When evaluated in separate cohorts, the score stratified women with suspected coronary disease into groups with a gradually increasing frequency of coronary disease and death.

Exercise testing scores as an example of better decisions through science

INTRODUCTION

The application of common statistical techniques to clinical and exercise test data has the potential to become a useful tool for assisting in the diagnosis of coronary artery disease, assessing prognosis, and reducing the cost of evaluating patients with suspected coronary disease. Since general practitioners function as gatekeepers and decide which patients must be referred to the cardiologist, they need to optimally use the basic tools they have available (i.e., history, physical exam, and the exercise test).

METHODS

Review of the literature with a focus on the scientific techniques for aiding the decision-making process.

RESULTS

Scores derived from multivariable statistical techniques considering clinical and exercise data have demonstrated superior discriminating power when compared using receiver-operating-characteristic curves with the ST segment response. In addition, by stratifying patients as to probability of disease and prognosis, they provide a management strategy. While computers as part of information management systems can calculate complicated equations to provide scores, physicians are reluctant to trust them. Thus, these scores have been represented as nomograms or simple additive tables so physicians are comfortable with their application. Scores have also been compared with physician judgment and been found to estimate the presence of coronary disease and prognosis as well as expert cardiologists, and often better than nonspecialists.

CONCLUSION

Multivariate scores can empower the clinician to assure the cardiac patient with access to appropriate and cost-effective cardiological care.

Better decisions through science: exercise testing scores

Statistical tools can be used to create scores for assisting in the diagnosis of coronary artery disease and assessing prognosis. General practitioners and internists frequently function as gatekeepers, deciding which patients must be referred to the cardiologist. Therefore, they need to use the basic tools they have available (ie, history, physical examination and the exercise test) in an optimal fashion. Scores derived from multivariable statistical techniques considering clinical and exercise data have demonstrated superior discriminating power compared with diagnosis only using the ST segment response. In addition, by stratifying patients as to probability of disease and prognosis, they provide a more practical management strategy than a response of normal or abnormal. Although computers, as part of information management systems, can calculate complicated equations and derive these scores, physicians are reluctant to trust them. However, when represented as nomograms or simple additive discrete pieces of information, scores are more readily accepted. The scores have been compared with physician judgment and have been found to estimate the presence of coronary disease and prognosis as well as expert cardiologists and often better than nonspecialists. However, the discriminating power of specific variables from the medical history and exercise test remains unclear because of inadequate study design and differences in study populations. Should expired gases be substituted for estimated METs? Should ST/heart rate index be used instead of putting ST depression and heart rate separately into the models? Should right-sided chest leads and heart rate in recovery be considered? There is a need for further evaluation of these easily obtained variables to improve the accuracy of prediction algorithms, especially in women. The portability and reliability of scores must be ensured because access to specialized care must be safeguarded. Assessment of the clinical and exercise test data and application of the newer scores can empower the clinician to assure the cardiac patient access to appropriate and cost-effective cardiologic care.

Diagnostic exercise tests on 4000 consecutive men

OBJECTIVE

Our purpose was to report the prevalence of abnormal treadmill test responses and their association with mortality in a large consecutive series of patients referred for standard diagnostic exercise tests, with testing performed and reported in a standardized fashion.

BACKGROUND

Exercise testing is widely performed, but an analysis of responses has not been presented for a large number of consecutive tests performed on patients referred for diagnosis of cardiac disease.

METHODS

All patients referred for evaluation at 2 university-affiliated Veterans Affairs Medical Centers who underwent exercise treadmill tests for clinical indications between 1987 and 2000 were determined to be dead or alive according to the Social Security Death Index after a mean 5.9-year follow-up. Patients with established heart disease (ie, prior coronary bypass surgery, myocardial infarction, or congestive heart failure) were excluded from analyses. Clinical and exercise test variables were collected prospectively according to standard definitions; testing and data management were performed in a standardized fashion with a computer-assisted protocol. All-cause mortality was used as the end point for follow-up. Standard survival analysis was performed, including Kaplan-Meier curves and a Cox hazard model.

RESULTS

After the exclusions, 3974 men (mean age 57.5 +/- 11 years) had standard diagnostic exercise testing over the study period with a mean of 5.9 (+/-3.7) years of follow-up (64% of all tested). There were no complications of testing in this clinically referred population, 82% of whom were referred for chest pain, risk factors, or signs and symptoms of ischemic heart disease. Five hundred forty-nine (14%) had a history of typical angina. Indications for testing were in accordance with published guidelines. A total of 545 died, yielding an annual mortality rate of 1.8%. The Cox hazard model chose the following variables in rank order as independently associated with time to death: change in rate pressure product, age greater than 65 years, METs less than 5, and electrocardiographic left ventricular hypertrophy. A score based on these variables classified patients into low-, medium-, and high-risk groups. The high-risk group with a score greater than 3 has a hazard ratio of 4 (95% confidence interval 3.82-4.27) and an annual mortality rate of 4%.

CONCLUSION

This comprehensive analysis provides rates of various abnormal responses that can be expected in men referred for diagnostic exercise testing at typical Veterans Administration Medical Centers. Four simple variables combined as a score predict all-cause mortality after clinical decisions for therapy are prescribed.