A consensus approach to diagnosing coronary artery disease based on clinical and exercise test data

Prognostic Impact of a Routine Six-Month Exercise Stress Test after Complex Left Main Bifurcation Percutaneous Intervention

The prognostic value of exercise stress test after complex left main (LM) coronary artery bifurcation (LM) stenting has been poorly investigated. To partially fill this gap in knowledge, we retrospectively analyzed the procedural and medical data of consecutive patients referred to our center for complex LM bifurcation disease between January 2008 and May 2018 who were treated using either single- or dual-stenting techniques. The prognostic impact of an exercise stress test, performed 6 months after the coronary intervention, was evaluated in 502 patients (316 males, mean age 70.3 ± 12.8 years, mean Syntax score 31.6 ± 6.3). At follow up after a mean of 37.1 ± 10.8 months (range 22.1-47.3 months), the target lesion failure (TLF) rate was 10.1% while stent thrombosis and cardiovascular mortality were 1.2 and 3.6%, respectively. A positive exercise stress test was detected at 6-month follow up in 42 out of 502 patients (8.4%); the incidence of a significant restenosis was 7.6% (n = 38). Patients with a negative exercise stress test at 6-month follow up had higher freedom from TLF and improved survival compared to those with a positive exercise stress test.

Effectiveness of cardiogoniometry compared with exercise-ECG test in diagnosing stable coronary artery disease in women

AIMS

To investigate the effectiveness of cardiogoniometry, a novel, non-invasive method, in diagnosing coronary artery disease (CAD) in women and compare it with exercise-ECG test, by using coronary angiography as a reference method.

METHODS

It was a single-centre, case-series study including consecutive female patients with stable angina pectoris (AP) undergoing coronary angiography. Exercise-ECG test, done according to the Bruce protocol, and cardiogoniometry were obtained prior to coronary angiography. Clinically significant CAD has been defined as one or more coronary lesions with >70% stenosis.

RESULTS

Study included 114 consecutive female patients with median age of 64.0 (58.0-71.0) years, out of which 32 (28.1%) had CAD. Cardiogoniometry yielded a total accuracy of 74.6% with a sensitivity of 75.0% (95% CI 56.6-88.5) and specificity of 74.4% (95% CI 63.6-83.4). Exercise-ECG test yielded a total accuracy of 45.1% with a sensitivity of 68.1% (95% CI 42.7-83.6) and specificity 36.6% (95% CI 25.2-50.3). Cardiogoniometry showed higher accuracy than exercise-ECG test ( P < 0.001). Pathological cardiogoniometry was associated with almost nine times higher risk for CAD (OR 8.7, 95%CI 3.4-22.3, P < 0.001), which remained significant after adjustment for age, and hypokinesia.

CONCLUSION

Cardiogoniometry is a non-invasive, easy-to-use and free-of-risk method which showed high effectiveness in diagnosing stable CAD in women and superior to exercise-ECG test. Cardiogoniometry could be introduced as a part of the diagnostic algorithm of screening women for stable CAD and is suitable for use in the primary setting, especially in women unable to undergo stress-testing.

Safety of symptom-limited exercise testing in a big cohort of a modern ICD population

BACKGROUND

Exercise may predispose to ventricular arrhythmias especially in patients with congestive heart failure. As therapy with implanted cardioverter-defibrillators (ICDs) has become standard medical care, there is an emerging number of exercise tests that need to be performed in patients with ICDs. In contrast, little is known about the safety of symptom-limited exercise testing in these patients.

METHODS AND RESULTS

400 ICD patients performed symptom-limited exercise treadmill testing. 200 patients performed a ramp protocol with an initial workload of 0 W increased by 15 W every minute. Another 200 ICD patients did a slightly modified ramp protocol with again an initial workload of 0 W but with an increased capacity of 15 W every 2 min. The study population consists mainly of patients with ischemic (63%) and non-ischemic (34%) heart disease. Atrial fibrillation was present in 16% of the subjects. The mean ejection fraction was 28 ± 8, and 78% of the patients had an ejection fraction below 30%. In this cohort of patients, no sustained ventricular arrhythmias and no deaths occurred during or after exercise testing. No inappropriate shock delivery was observed. The modified ramp protocol resulted in a prolonged exercise time with equal exercise capacity but does not result in an enhanced susceptibility for ventricular arrhythmias.

CONCLUSIONS

Symptom-limited exercise treadmill testing in heart failure patients with ICDs is a safe procedure. The use of a ramp protocol is sufficient in terms of safety and is easy to perform in general practice. The exercise duration in heart failure patients with ICDs does not predict serious adverse events.

VALUE OF SPECIFIC PARAMETERS AND INTEGRATIVE INDICES OF TREADMILL TEST FOR THE ASSESSMENT OF CORONARY STENOSIS SEVERITY

Aim.To assess the value of specific parameters and integrated indices (II; such as Duke Index (DI), Centre for Preventive Medicine Index (CPMI), and modified CPMI) of the treadmill test in the diagnostics of coronary stenosis severity among patients with stable coronary heart disease (CHD).

Material and methods.The study included all patients (260 permanent residents of Moscow City or Moscow Region) who were admitted to the State Research Centre for Preventive Medicine with the CHD diagnosis and who underwent coronary angiography (CAG) and treadmill test in the period between January 1st 2004 and December 31st 2007.

Results.There were statistically significant associations between the main treadmill test parameters and the severity of coronary artery (CA) atherosclerosis. The larger number of stenosis-affected CA was associated with a higher prevalence of chest pain and treadmill tests with positive results and ST segment depression >1 mm, as well as with a decreased total duration of treadmill test. Similarly, the increased risk, as assessed by treadmill test indices (DI, CPMI, and modified CPMI), was linked to an increased number of stenosis-affected CA. Modified CPMI demonstrated the highest diagnostic value for the assessment of coronary atherosclerosis severity.

Conclusion.The treadmill test parameters which demonstrated their diagnostic value for the assessment of CHD severity included the following: positive test results, retrosternal chest pain as the reason for test discontinuation, ST segment depression >1mm, and short total duration of the test. Overall, all II demonstrated their high value in CHD diagnostics. Modified CPMI was the most effective II in the assessment of CA atherosclerosis severity. 

Pre-exercise cardiology screening guidelines for asymptomatic patients with diabetes

Coronary heart disease is a major cause of morbidity and mortality in persons with diabetes mellitus. Exercise is an important cornerstone in the treatment and management of diabetes but is also associated with a heightened risk of sudden cardiac death in those with occult coronary heart disease. Before beginning a physical activity program that involves anything greater than moderate intensity exercise, consideration should be given to screening asymptomatic persons with diabetes for silent myocardial ischemia.

Mitochondrial DNA haplogroup T is associated with coronary artery disease and diabetic retinopathy: a case control study

Background

There is strong and consistent evidence that oxidative stress is crucially involved in the development of atherosclerotic vascular disease. Overproduction of reactive oxygen species (ROS) in mitochondria is an unifying mechanism that underlies micro- and macrovascular atherosclerotic disease. Given the central role of mitochondria in energy and ROS production, mitochondrial DNA (mtDNA) is an obvious candidate for genetic susceptibility studies on atherosclerotic processes. We therefore examined the association between mtDNA haplogroups and coronary artery disease (CAD) as well as diabetic retinopathy.

Methods

This study of Middle European Caucasians included patients with angiographically documented CAD (n = 487), subjects with type 2 diabetes mellitus with (n = 149) or without (n = 78) diabetic retinopathy and control subjects without clinical manifestations of atherosclerotic disease (n = 1527). MtDNA haplotyping was performed using multiplex PCR and subsequent multiplex primer extension analysis for determination of the major European haplogroups. Haplogroup frequencies of patients were compared to those of control subjects without clinical manifestations of atherosclerotic disease.

Results

Haplogroup T was significantly more prevalent among patients with CAD than among control subjects (14.8% vs 8.3%; p = 0.002). In patients with type 2 diabetes, the presence of diabetic retinopathy was also significantly associated with a higher prevalence of haplogroup T (12.1% vs 5.1%; p = 0.046).

Conclusion

Our data indicate that the mtDNA haplogroup T is associated with CAD and diabetic retinopathy in Middle European Caucasian populations.

The Value of Graded Exercise Testing in Today's World

With the continued high prevalence of coronary artery disease in our country, the need for diagnostic testing for myocardial ischemia will continue to be a high priority. Many advances have been made in the field of diagnostic testing for myocardial ischemia, but the combination of graded exercise testing (GXT) with 12-lead electrocardiogram (with or without nuclear perfusion imaging or echocardiography) continues to be the initial noninvasive test most accepted in the medical field. However, it is imperative that the patient is able and willing to give a good physical effort to increase the sensitivity in detecting disease. In addition to using GXT for diagnostic purposes, the GXT is also beneficial in respect to determining long-term prognosis, assessing therapeutic interventions, and assessing one's functional capacity for the purpose of determining appropriate and safe exercise training.

A comparison of treadmill scores to diagnose coronary artery disease

BACKGROUND

Recently, several treadmill scores have been proposed as means for improving the diagnostic accuracy of the exercise treadmill test (ETT). Questions remain regarding the diagnostic accuracy of treadmill scores when applied to a different patient population than that from which they were derived; furthermore, many treadmill scores have not been compared with one another in the same population.

HYPOTHESIS

The diagnostic accuracy of treadmill scores may not be the same.

METHODS

A retrospective analysis of data collected prospectively was performed on consecutive patients referred for evaluation of chest pain. All patients underwent a standard ETT followed by coronary angiography. Using angiographic evidence of coronary artery disease (CAD) as a reference, the area under the curve (AUC) of receiver operator characteristic (ROC) plots of the ST response alone, the Duke Treadmill Score (DTS), the Morise score, the Detrano score, the VA score, and a Consensus score consisting of the Morise, Detrano, and VA scores together were calculated and compared. The predictive accuracies of the DTS and the Consensus score to stratify patients for the likelihood of CAD were calculated and compared.

RESULTS

In all, 1,282 patients without a prior myocardial infarction had an ETT and coronary angiography. The AUC (+/- standard error) was 0.67+/-0.01 for the ST response, 0.73+/-0.01 for DTS, 0.76+/-0.01 for Detrano score, 0.77+/-0.01 for Morise score, 0.78+/-0.01 for VA score, and 0.78+/-0.01 for Consensus score. The AUC for each treadmill score was significantly higher (z-score > 1.96) than for the ST response alone. The AUC of DTS was significantly lower than all other treadmill scores (z-score > 1.96). The predictive accuracy (+/-95% confidence interval) of the DTS to risk stratify patients into high and low likelihood for CAD was 71 (65-77)%, versus 80 (74-86)% for the Consensus score (p < 0.0001).

CONCLUSION

In this population, the DTS remains useful for diagnosing CAD and stratifying for the likelihood of CAD, although it is less accurate than other treadmill scores.

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.

Coronary artery disease is common in nonuremic, asymptomatic type 1 diabetic islet transplant candidates

OBJECTIVE

Coronary artery disease (CAD) is the most common cause of death in patients with type 1 diabetes. Asymptomatic CAD is common in uremic diabetic patients, but its prevalence in nonuremic type 1 diabetic patients is unknown. The prevalence of CAD was determined by coronary angiography and the performance of noninvasive cardiac investigation evaluated in type 1 diabetic islet transplant (ITX) candidates with preserved renal function.

RESEARCH DESIGN AND METHODS

A total of 60 consecutive type 1 diabetic ITX candidates (average age 46 years [mean 24-64], 23 men, and 47% ever smokers) underwent coronary angiography, electrocardiographic stress testing (EST), and myocardial perfusion imaging (MPI) in a prospective cohort study. CAD was indicated on angiography by the presence of stenoses >50%. Models to predict CAD were examined by logistic regression.

RESULTS

Most subjects (53 of 60) had no history or symptoms of CAD; 23 (43%) of these asymptomatic subjects had stenoses >50%. CAD was associated with age, duration of diabetes, hypertension, and smoking. Although specific, EST and MPI were not sensitive as predictors of CAD on angiography (specificity 0.97 and 0.93, sensitivity 0.17 and 0.04, respectively) but helped identify two of three subjects requiring revascularization. EST and MPI did not enhance logistic regression models. A clinical algorithm to identify low-risk subjects who may not require angiography was highly sensitive but was applicable only to a minority (n = 8, sensitivity 1.0, specificity 0.27, negative predictive value 1.0).

CONCLUSIONS

Nonuremic type 1 diabetic patients with hypoglycemic unawareness and/or metabolic lability referred for ITX are at high risk for asymptomatic CAD despite negative noninvasive investigations. Aggressive management of cardiovascular risk factors and further investigation into optimal cardiac risk stratification in type 1 diabetes are warranted.

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.

Diagnosing coronary artery disease in diabetic patients

Although several diagnostic modalities are available to the clinician interested in diagnosing coronary artery disease, very few have been validated in diabetic populations. This review discusses the non-invasive diagnosis of coronary disease in diabetic patients. Evidence regarding the prevalence and prognostic significance of silent ischemia is reviewed and the potential impact of silent ischemia on the diagnostic characteristics of the exercise treadmill test discussed. Other diagnostic tools are considered, and recommendations are made with respect to screening asymptomatic diabetic patients for coronary artery disease.

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.

Heart rate recovery: validation and methodologic issues

OBJECTIVES

The goal of this study was to validate the prognostic value of the drop in heart rate (HR) after exercise, compare it to other test responses, evaluate its diagnostic value and clarify some of the methodologic issues surrounding its use.

BACKGROUND

Studies have highlighted the value of a new prognostic feature of the treadmill test-rate of recovery of HR after exercise. These studies have had differing as well as controversial results and did not consider diagnostic test characteristics.

METHODS

All patients were referred for evaluation of chest pain at two university-affiliated Veterans Affairs Medical Centers who underwent treadmill tests and coronary angiography between 1987 and 1999 as predicted after a mean seven years of follow-up. All-cause mortality was the end point for follow-up, and coronary angiography was the diagnostic gold standard.

RESULTS

There were 2,193 male patients who had treadmill tests and coronary angiography. Heart rate recovery at 2 min after exercise outperformed other time points in prediction of death; a decrease of <22 beats/min had a hazard ratio of 2.6 (2.4 to 2.8 95% confidence interval). This new measurement was ranked similarly to traditional variables including age and metabolic equivalents but failed to have diagnostic power for discriminating those who had angiographic disease.

CONCLUSIONS

Heart rate at 1 or 2 min of recovery has been validated as a prognostic measurement and should be recorded as part of all treadmill tests. This new measurement does not replace, but is supplemental to, established scores.

Assessing patients with possible heart disease using scores

Multivariable analysis of 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 are functioning as gatekeepers and decide which patients must be referred to the cardiologist, they need to use the basic tools they have available (i.e. 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 simple classification of the ST 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 run complicated equations and derive these 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. Their results have also been compared with physician judgment and 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 metabolic equivalents (METs)? Should ST/heart rate (HR) index be used instead of putting these measurements separately into the models? Should right-sided chest leads and HR in recovery be considered? There is a need for further evaluation of these routinely obtained variables to improve the accuracy of prediction algorithms especially in women. The portability and reliability of these equations must be demonstrated since access to specialised care must be safe-guarded. Hopefully, sequential assessment of the clinical and exercise test data and application of the newer generation of multivariable equations can empower the clinician to assure the cardiac patient access to appropriate and cost-effective cardiological care.

Clinical and exercise test predictors of all-cause mortality: results from > 6,000 consecutive referred male patients

OBJECTIVE

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

BACKGROUND

Exercise testing is widely performed, but few databases exist of large numbers of consecutive tests performed on patients referred for routine clinical purposes using standardized methods. Even fewer of the available databases have information regarding all-cause mortality as an outcome.

METHODS

All patients referred for evaluation at two university-affiliated Veterans Affairs medical centers who underwent exercise treadmill testing for clinical indications between 1987 and 2000 were determined to be dead or alive using the Social Security death index after a mean 6.2 years (median, 7 years) of follow-up. Clinical and exercise test variables were collected prospectively according to standard definitions; testing and data management were performed in a standardized fashion using a computer-assisted protocol. All-cause mortality was utilized as the end point for follow-up. Standard survival analysis was performed, including Kaplan-Meier curves and a Cox hazard model.

RESULTS

There were 6,213 male patients (mean +/- SD age, 59 +/- 11 years) who underwent standard exercise ECG treadmill testing over the study period with a mean follow-up duration of 6.2 +/- 3.7 years. There were no complications of testing in this clinically referred population, 78% of whom were referred for chest pain, or risk factors or signs or symptoms of ischemic heart disease. Overlapping thirds had typical angina or history of myocardial infarction (MI). Five hundred seventy-nine patients had prior coronary artery bypass surgery, and 522 patients had a history of congestive heart failure (CHF). Indications for testing were in accordance with published guidelines. Twenty percent died over the follow-up period, for an average annual mortality rate of 2.6%. Cox hazard function chose the following variables in rank order as independently and significantly associated with time to death: exercise capacity (metabolic equivalents < 5, age > 65 years, history of CHF, and history of MI. A score based on these variables (summing up the four variables [if yes = 1 point]) classified patients into low-risk, medium-risk, and high-risk groups. The high-risk group (score > or = 3) has a hazard ratio of 5.0 (95% confidence interval, 4.7 to 5.3) and a 5-year mortality rate of 31%.

CONCLUSION

This comprehensive analysis provides rates of various abnormal responses that can be expected in patients referred for exercise testing at a typical medical center. Four simple variables combined as a score powerfully stratified patients according to prognosis.

Clinical utility of the exercise ECG in patients with diabetes and chest pain

OBJECTIVE

The purpose of this study was to determine the characteristics of exercise treadmill testing in diabetic patients presenting with chest pain.

BACKGROUND

The diagnosis of coronary artery disease (CAD) in diabetic patients is confounded by different manifestations of coronary disease than are seen in the general population. Because of the association of diabetes with accelerated CAD, it is critical to assess the diagnostic utility of the standard exercise test in diabetic patients with chest pain.

METHODS

This study was a retrospective analysis of standard exercise test results in 1,282 male patients without prior myocardial infarction who had undergone coronary angiography and were being evaluated for possible CAD at two Veterans' Administration institutions.

RESULTS

In patients with diabetes, 38% had an abnormal exercise test result, and the prevalence of angiographic CAD was 69%; the sensitivity of the exercise test was 47% (95% confidence interval [CI], 41 to 58), and specificity was 81% (95% CI, 68 to 89). In patients without diabetes, 38% had an abnormal exercise test result, and the prevalence of angiographic CAD was 58%; the sensitivity of the exercise test was 52% (95% CI, 48 to 56), and specificity was 80% (95% CI, 76 to 83). The receiver operating characteristic curves were also similar in both diabetic and nondiabetic patients (0.67 and 0.68, respectively).

CONCLUSION

These data demonstrate that the standard exercise test has similar diagnostic characteristics in diabetic as in nondiabetic patients.

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.

Performing the exercise test

Exercise testing is useful in assessing physical fitness, determining functional capacity, diagnosing ischemic heart disease, defining the prognosis of ischemic heart disease, developing an exercise prescription, and guiding cardiac rehabilitation. This article outlines the current indications, contraindications, and special considerations for exercise testing. Specific protocols are discussed along with physician responsibilities for performing this procedure. A summary of current testing equipment is included.

Using patient-reportable clinical history factors to predict myocardial infarction

Using a derivation data set of 1253 patients, we built several logistic regression and neural network models to estimate the likelihood of myocardial infarction based upon patient-reportable clinical history factors only. The best performing logistic regression model and neural network model had C-indices of 0.8444 and 0.8503, respectively, when validated on an independent data set of 500 patients. We conclude that both logistic regression and neural network models can be built that successfully predict the probability of myocardial infarction based on patient-reportable history factors alone. These models could have important utility in applications outside of a hospital setting when objective diagnostic test information is not yet be available.

Exercise testing in clinical medicine

Exercise-induced changes in the electrocardiogram have been used to identify coronary artery disease for almost a century. Over the past decade, however, clinicians have increasingly focused on more expensive diagnostic tools believing them to offer improved diagnostic accuracy. In fact, by incorporating historical data, the simple exercise test can in most cases outperform the newer tests. The use of prediction equations and non-staged exercise protocols can improve the test still further, while advances in the use of the test for prognosis, with the discovery of novel risk factors and the addition of gas analysis, may in the future shift the primary emphasis away from diagnosis. Brief, inexpensive, and done in most cases without the presence of a cardiologist, the exercise test offers the highest value for predictive accuracy of any of the non-invasive tests for coronary artery disease.

Maximizing the exercise stress test. Critical factors that enhances its validity

The maximal exercise stress test continues to be an important diagnostic and prognostic tool in the primary care office setting. But are you getting the most accurate information possible? Drs Driggers and Marchant discuss several factors that are crucial to the test's validity--and thus to its usefulness in your clinical practice.