"Recovery only" ST-segment depression and the predictive accuracy of the exercise test

Thirty years of research on physical activity, mental health, and wellbeing: A scientometric analysis of hotspots and trends

The sheer volume of research publications on physical activity, mental health, and wellbeing is overwhelming. The aim of this study was to perform a broad-ranging scientometric analysis to evaluate key themes and trends over the past decades, informing future lines of research. We searched the Web of Science Core Collection from inception until December 7, 2021, using the appropriate search terms such as "physical activity" or "mental health," with no limitation of language or time. Eligible studies were articles, reviews, editorial material, and proceeding papers. We retrieved 55,353 documents published between 1905 and 2021. The annual scientific production is exponential with a mean annual growth rate of 6.8% since 1989. The 1988-2021 co-cited reference network identified 50 distinct clusters that presented significant modularity and silhouette scores indicating highly credible clusters (Q = 0.848, S = 0.939). This network identified 6 major research trends on physical activity, namely cardiovascular diseases, somatic disorders, cognitive decline/dementia, mental illness, athletes' performance, related health issues, and eating disorders, and the COVID-19 pandemic. A focus on the latest research trends found that greenness/urbanicity (2014), concussion/chronic traumatic encephalopathy (2015), and COVID-19 (2019) were the most active clusters of research. The USA research network was the most central, and the Chinese research network, although important in size, was relatively isolated. Our results strengthen and expand the central role of physical activity in public health, calling for the systematic involvement of physical activity professionals as stakeholders in public health decision-making process.

Performance and Interpretation of Office Exercise Stress Testing

In an era where cardiovascular disease continues to increase in prevalence, chest pain is a commonly encountered complaint in the outpatient setting. Clinicians are often tasked with the challenge of selecting the most appropriate screening tool in the evaluation of a patient with suspected coronary artery disease. With proper consideration of indications and contraindications, exercise electrocardiogram (ECG) stress testing is an accessible, cost-conscious, and validated outpatient diagnostic modality for predicting coronary artery disease.

Significance of 'recovery ST-segment depression' in exercise stress test

Objective

To study the significance of ST-segment depression during ‘recovery’ compared to that ‘during stress’ and ‘both the phases’ in exercise stress test.

Methods

Patients with positive exercise stress test who underwent coronary angiography (CAG) from 1st January 2017 to 31st December 2018 were studied. Patients were divided into 3 groups- Group A with ST-depression restricted to recovery phase, group B with ST-depression restricted to stress phase and group C with ST-depression seen both during exercise and recovery. All patients underwent CAG. Sensitivity, specificity, and predictive values of each of these groups in diagnosis of significant coronary artery disease (CAD) were analysed and compared.

Results

Total 300 patients were studied. Mean age of the study population was 48.77 ± 7.94 years. 78.3% of patients with positive exercise stress test had significant CAD. 96% of patients in group A had significant CAD, which was higher than in group B (88.9%) & group C (70.1%). The specificity, positive predictive value and negative predictive value of ST-segment depression in group A (96.92%, 96% and 25.2% respectively) were higher than that of ST-depression in group B (89.23%, 88.89% and 24.47% respectively) and group C (13.85%, 70.05% and 7.96% respectively). Sensitivity and accuracy of ST-depression in group A were lower (20.43% and 37% respectively), compared to other 2 groups.

Conclusion

Patient with ST-depression restricted to recovery phase had highest specificity, positive predictive value, and negative predictive value. However, accuracy was highest in group with both stress phase and exercise ST-segment depression.

Addition of the duration of ST segment depression to Duke treadmill score for diagnostic accuracy of exercise electrocardiography to predict obstructive coronary artery disease

INTRODUCTION

Exercise electrocardiography (EET) is a safe and cost-effective method to predict the presence, prognosis, and severity of coronary artery disease (CAD). Various score models have been developed to increase predictive power of EET. In this study, we aimed to evaluate whether adding ST depression duration could have an effect on increasing the value of Duke treadmill score (DTS) in predicting obstructive CAD.

METHODS

In this single centred, cross-sectional study, we evaluated a total of 258 patients who presented with a complaint of chest pain and undergone coronary angiogram in result of a positive EET. DTS was calculated for all the patients. The new score-revised DTS- was calculated by adding total ST depression time to classical DS parameters. We compared area under the curve (AUC) of DTS and revised DTS by Delongi method.

RESULTS

Mean age of the group was 58.43 ± 9.37, and 37.2% (n = 96) were female. Mean total ST-depression duration was 171.72 ± 91.43 msec in normal artery group,241.54 ± 118.11 msec in non-obstructive CAD group, and 281.26 ± 113.64 in obstructive CAD group.ST-depression duration in both exercise and recovery, and total ST depression duration were significantly higher in obstructive CAD group than non-obstructive and normal artery groups (p = 0.024, p = 0.01, p < 0.01, and p < 0.01, respectively). Revised DTS had significantly higher predictive value of obstructive CAD compared to classical DS (AUC (95%CI): 0.744 vs. 0.626, p < 0.001). The AUC of DS was significantly lower than the new score (z-score:3.274, p = 0.011).

CONCLUSION

In conclusion, adding ST depression duration to DTS calculation is increasing the discriminative value of DTS to predict obstructive CAD. Benefits of EET within the context of the management of CAD is well-known, hence, it is clear that physicians may use revised DTS.

Rest premature ventricular contractions on routine ECG and prognosis in heart failure patients

BACKGROUND

Premature ventricular contractions (PVC) at rest are frequently seen in heart failure (HF) patients but conflicting data exist regarding their importance for cardiovascular (CV) mortality. This study aims to evaluate the prognostic value of rest PVCs on an electrocardiogram (ECG) in patients with a history of clinical HF.

METHODS AND RESULTS

We considered 352 patients (64 + or - 11 years; 7 females) with a history of clinical HF undergoing treadmill testing for clinical reasons at the Veterans Affairs Palo Alto Health Care System (VAPAHCS) (1987-2007). Patients with rest PVCs were defined as having > or = 1 PVC on the ECG prior to testing (n = 29; 8%). During a median follow-up period of 6.2 years, there were 178 deaths of which 76 (42.6%) were due to CV causes. At baseline, compared to patients without rest PVCs, those with rest PVCs had a lower ejection fraction (EF) (30% vs 45%) and the prevalence of EF < or = 35% was higher (75% vs 41%). They were more likely to have smoked (76% vs 55%).The all-cause and CV mortality rates were significantly higher in the rest PVCs group (72% vs 49%, P = 0.01 and 45% vs 20%, P = 0.002; respectively). After adjusting for age, beta-blocker use, rest ECG findings, resting heart rate (HR), EF, maximal systolic blood pressure, peak HR, and exercise capacity, rest PVC was associated with a 5.5-fold increased risk of CV mortality (P = 0.004). Considering the presence of PVCs during exercise and/or recovery did not affect our results.

CONCLUSION

The presence of PVC on an ECG is a powerful predictor of CV mortality even after adjusting for confounding factors.

Asymptomatic ST-segment depression during exercise testing and the risk of sudden cardiac death in middle-aged men: a population-based follow-up study

AIMS

Silent electrocardiographic ST change predicts future coronary events in patients with coronary heart disease (CHD), but the prognostic significance of asymptomatic ST-segment depression with respect to sudden cardiac death in subjects without apparent CHD is not well known.

METHODS AND RESULTS

We investigated the association between silent ST-segment depression during and after maximal symptom-limited exercise test and the risk of sudden cardiac death in a population-based sample of 1769 men without evident CHD. A total of 72 sudden cardiac death occurred during the median follow-up of 18 years. The risk of sudden cardiac death was increased among men with asymptomatic ST-segment depression during exercise [hazard ratio (HR) 2.1, 95% confidence interval (CI) 1.2-3.9] as well as among those with asymptomatic ST-segment depression during recovery period (HR 3.2, 95% CI 1.7-6.0). Asymptomatic ST-depression during exercise testing was a stronger predictor for the risk of sudden cardiac death especially among smokers as well as in hypercholesterolaemic and hypertensive men than in men without these risk factors.

CONCLUSION

Asymptomatic ST-segment depression was a very strong predictor of sudden cardiac death in men with any conventional risk factor but no previously diagnosed CHD, emphasizing the value of exercise testing to identify asymptomatic high-risk men who could benefit from preventive measures.

Age and double product (systolic blood pressure x heart rate) reserve-adjusted modification of the Duke Treadmill Score nomogram in men

The Duke Treadmill Score (DTS) is an established clinical tool for risk stratification. Our aim was to determine if other variables could improve the prognostic power of the DTS and if so, to modify the DTS nomogram. From a total of 1,959 patients referred for exercise testing at the Palo Alto VA Medical Center from 1997 to 2006 (a mean follow-up of 5.4 years), we studied 1,759 male veterans (age 57 +/- 12 years) free of heart failure. Double product (DP) was calculated by multiplying systolic blood pressure and heart rate; variables and their products were subtracted to obtain the differences between at rest and maximal exercise (reserve) and recovery. Of all the hemodynamic measurements, DP reserve was the strongest predictor of cardiovascular death (CVD) (Wald Z-score -3.84, p <0.001) after adjustment for potential confounders. When the components of DTS were entered in the Cox hazard model with DP reserve and age, only DP reserve and age were chosen (p <0.00001). Using the Cox coefficients, a score calculated by [age - DTS - 3 x (DP reserve/1,000)] yielded an area under the curve of 0.84 compared with 0.76 for the DTS. Using this equation, a nomogram was constructed by adding age and DP reserve to the original DTS nomogram improving estimation of annual CVD. In conclusion, we propose an age and DP reserve-adjusted DTS nomogram that improves the prognostic estimates of average annual CVD over the DTS alone.

Prognostic value of double product reserve

Background

Although the prognostic power of exercise capacity has been demonstrated, the relative prognostic potential of other hemodynamic responses has not been thoroughly investigated. We aimed to assess the prognostic power of double product (DP) parameters in patients referred for standard exercise testing.

Design

A retrospective cohort study.

Methods

Analyses were performed on 1959 patients referred for exercise testing at the Palo Alto Veterans Affairs Medical Center from 1997 to 2006. After removal of female and heart failure patients, 1759 male veterans (mean age 57 ± 12 years) remained. DP was calculated by multiplying systolic blood pressure (SBP) and heart rate (HR); variables and their products were subtracted to obtain the differences between rest and maximal exercise (reserve), and recovery.

Results

Multivariate Cox survival analysis was performed for 157 all-cause and 53 cardiovascular deaths during a mean follow-up of 5.4 ± 2.1 years. Although most of the hemodynamic variables were individually significant in Cox survival analysis, when age, DP reserve, exercise capacity (in metabolic equivalents), and HR recovery were entered together, only age and DP reserve were chosen. Of all hemodynamic measurements considered, DP reserve was the strongest predictor of cardiovascular prognosis after adjustment for age (Wald Z-score,-5.12; P < 0.0001) and when considering other potential confounders such as age, β-blocker use, and the Duke treadmill Score (Wald Z-score, –3.84; P < 0.0001).

Conclusion

In this study population, DP reserve had greater prognostic power than metabolic equivalents, maximal HR or systolic blood pressure, or HR recovery.

Age-adjusted modification of the Duke Treadmill Score nomogram

BACKGROUND

The Duke Treadmill Score (DTS) is an established clinical tool for risk stratification of patients referred for exercise testing, but it does not consider age. We aimed to determine if age could improve the prognostic power of the DTS and if so, to modify the DTS nomogram to include age.

METHODS

Of 1,959 patients referred for exercise testing from 1997 to 2006, 1,759 male veterans (age range 23-86 years) remained after exclusion of female and patients with heart failure. Cardiovascular mortality was the main outcome considered.

RESULTS

Cox survival analysis was performed entering age and the DTS; both were significant (P <or= .002) with similar Wald Z values (5.4 and -3.1) and regression coefficients but opposite signs. The score: age-DTS yielded an area under the receiver operating characteristic curve of 0.80 compared with 0.76 for the DTS (P < .001). Using this equation, a nomogram was constructed by adding age to the original DTS nomogram. The point at which the age-DTS line intersects the drawing line from the DTS to the corresponding value for age indicates average annual cardiovascular (CV) mortality adjusted for age. For a DTS associated with a 2.5% annual CV mortality, an age of 30 compared with 70 decreased CV risk by a factor of 10 to less than 0.2% (P < .05, log-rank test).

CONCLUSIONS

We propose an age-adjusted DTS nomogram that improves the prognostic estimates of average annual CV mortality over the DTS alone. This nomogram requires external validation and extension to women.

Prognostic significance of systolic blood pressure increases in men during exercise stress testing

Our aim was to investigate whether exercise-induced increase in systolic blood pressure (BP) measured during exercise stress testing (EST) adds prognostic information to cardiovascular (CV) mortality. EST is ideally suited to evaluate the prognostic power of systolic BP; it not only measures systolic BP response to exercise but also provides information about exercise capacity and other EST variables, which may affect the peak systolic BP. The study population consisted of 6,145 consecutive patients who underwent symptom-limited EST. Using the median value of change in systolic BP from baseline, patients were grouped according to exercise-induced increases in systolic BP<or=43 mm Hg (group A, n=3,062) and >or=44 mm Hg (group B, n=3,083). Multivariate analysis was used to adjust for baseline differences between the 2 groups with CV mortality as the end point for follow-up. Six thousand one hundred forty-five men underwent EST with a mean follow-up of 6.6 years. During follow-up, 676 patients died of CV causes with an average annual CV mortality of 1.6%. CV mortality was significantly higher in group A than in group B (13.7% vs 8.2%, p<0.001). After adjusting for baseline differences in the 2 groups using multivariate analysis, an increase in systolic BP of <or=44 mm Hg was a significant predictor of mortality (hazard ratio 1.2, 95% confidence interval 1.02 to 1.44, p<0.05). In conclusion, systolic BP response to maximal EST adds prognostic information to CV mortality independent of age, ST-segment abnormalities, and exercise capacity. In our study an increment in systolic BP of >or=44 mm Hg during EST was associated with a 23% improvement in survival over a mean follow-up of >6 years.

Prognostic Value of Heart Rate Increase at Onset of Exercise Testing

Background— The initial response of heart rate to dynamic exercise has been proposed as having prognostic value in limited studies that have used modalities other than the treadmill. Our aim was to evaluate the prognostic value of early heart rate parameters in patients referred for routine clinical treadmill testing.

Methods and Results— The heart rate rise at the onset of exercise was measured in 1959 patients referred for clinical treadmill testing at the Palo Alto (Calif) Veterans Affairs Medical Center from 1997 to 2004. Multivariable Cox survival analysis was performed for 197 all-cause and 74 cardiovascular deaths that accrued during a mean follow-up of 5.4±2.1 years. Decreased heart rate changes at all initial relative exercise workloads were associated with significantly increased all-cause mortality. The heart rate rise at one-third total exercise capacity, however, was the only early heart rate variable that significantly predicted both all-cause and cardiovascular risk after adjustment for confounders. Failing to reach 1 SD in the heart rate rise at one-third total exercise capacity was associated with a 28% increased all-cause mortality rate (hazard ratio, 0.72; 95% CI, 0.61 to 0.85; P <0.001) and a 35% cardiovascular mortality rate (hazard ratio, 0.65; 95% CI, 0.49 to 0.86; P =0.003). Of all heart rate measurements considered (initial and recovery), the heart rate increase at peak exercise was the most powerful predictor of cardiovascular prognosis after adjustment for potential confounders. The Duke treadmill score, however, was superior to all heart rate measurements in the prediction of cardiovascular mortality.

Conclusions— In the present study population, a rapid initial heart rate rise was associated with improved survival, but the heart rate increase at peak exercise and other conventional measurements such as exercise capacity and the Duke treadmill score were more powerful predictors of prognosis.

Significance of QRS duration changes in the evaluation of ST-segment depression presenting exclusively during the postexercise recovery period

BACKGROUND

The aim of this study was to evaluate the contribution of QRS prolongation in the diagnosis of coronary artery disease (CAD) in patients with exercise-induced ST-segment depression exclusively during the recovery period.

METHODS

The study population consisted of 107 patients (90 males and 17 females) aged 39-70 (mean 59 +/- 7) years who underwent a treadmill exercise test using Bruce protocol and presented ST-segment depression limited to the recovery period. Angiographic data were available for all studied patients.

RESULTS

Among studied patients, 74 (69%) were found to have hemodynamically significant CAD, while the remaining 33 (31%) had normal coronary arteries. Concomitant QRS prolongation was revealed in 61 (82%) of the patients with angiographically documented CAD, while in 13 (18%) patients QRS duration remained unchanged. On the contrary, only 4 (12%) of the 33 patients with normal coronary arteries showed prolonged QRS duration during ST depression, while in the remaining 29 (88%) QRS duration remained unchanged.

CONCLUSIONS

The evaluation of the concomitant QRS duration changes may discriminate patients with truly ischemia-induced ST-segment depression limited to the recovery period.

Exercise-induced ventricular arrhythmias and cardiovascular death

BACKGROUND

Exercise-induced ventricular arrhythmias (EIVA) are frequently observed during exercise testing. However, the clinical guidelines do not specify their significance and so we examined this issue in our population.

METHODS

A retrospective analysis of prospectively collected data was performed on 5754 consecutive male veterans referred for exercise testing at two university-affiliated Veterans Affairs Medical Centers. Exercise test responses were recorded and cardiovascular mortality was assessed after a mean follow-up of 6 +/- 4 years. EIVA were defined as frequent premature ventricular complexes (PVCs) constituting more than 10% of all ventricular depolarizations during any 30-second ECG recording, or a run of three or more consecutive PVCs during the exercise test or recovery.

RESULTS

EIVA occurred in 426 patients (7.4%). There were 550 (10.6%) cardiovascular deaths during follow-up. Seventy two (17%) patients with EIVA died of cardiovascular causes, whereas 478 (9.0%) of patients without EIVA died of cardiovascular causes (P < 0.001). Patients with EIVA had a higher prevalence of cardiovascular disease, resting PVCs, resting ST depression, and ischemia during exercise than patients without EIVA. In a Cox hazards model adjusted for age, cardiovascular disease, exercise-induced ischemia, ECG abnormalities, exercise capacity and risk factors, EIVA was significantly associated with time to cardiovascular death. The combination of both resting PVCs and EIVA was associated with the highest hazard ratio.

CONCLUSIONS

EIVA are independent predictors of cardiovascular mortality after adjusting for other clinical and exercise test variables; combination with resting PVCs carries the highest risk.

Diagnostic and prognostic value of ST segment depression limited to the recovery phase of exercise stress test

OBJECTIVES

To investigate the diagnostic and prognostic value of ST segment depression limited to the recovery phase of an exercise stress test, as compared with that of ST segment depression appearing during exercise.

SETTING

Exercise stress test laboratory of a university hospital.

PATIENTS AND DESIGN

Clinical and angiographic data were compared for 574 consecutive patients who developed ST segment depression during the active phase of an exercise test (group 1) and for 79 patients who developed ST segment depression only during the recovery phase of the exercise test (group 2).

RESULTS

There were no differences between the two groups in major clinical features. Significant coronary artery stenoses were found in 488 group 1 patients (85%) and in 62 group 2 patients (78%, p = 0.14). Three vessel or left main disease was found in 166 (29%) group 1 and in 14 (18%) group 2 patients (p = 0.045). At a median follow up of 55.3 months of 321 group 1 and 54 group 2 patients, there were no significant differences in major cardiac events between the groups (univariate relative risk 0.81, 95% confidence interval 0.25 to 2.68, p = 0.72).

CONCLUSION

The diagnostic and prognostic power of ST segment depression limited to the recovery phase of an exercise test is largely similar to that of ST segment depression induced during effort; thus, assessing ST segment depression during recovery can significantly improve the clinical information derived from exercise stress tests.

Health-Care Costs and Exercise Capacity

BACKGROUND

While the beneficial effect of exercise capacity on mortality is well-accepted, its effect on health-care costs remains uncertain. This study investigates the relationship between exercise capacity and health-care costs.

METHODS

The Veterans Affairs Health Care System recently implemented a Decision Support System that provides data on patterns of care, patient outcomes, workload, and costs. Total inpatient and outpatient costs were derived from existing administrative and clinical data systems, were adjusted for relative value units, and were expressed in relative cost units. We used univariable and multivariable analyses to evaluate the 1-year total costs in the year following a standard exercise test. Costs were compared with exercise capacity estimated in metabolic equivalents (METs), other test results, and clinical variables for 881 consecutive patients who were referred for clinical reasons for treadmill testing at the Palo Alto Veterans Affairs Health Care System facility between October 1, 1998, and September 30, 2000.

RESULTS

The patients had a mean age of 59 years, 95% were men, and 74% were white. Eight patients (< 1%) died during the year of follow-up. Exercise testing showed an average maximum heart rate of 138 beats/min, 8.2 METs, and a peak Borg scale of 17. In unadjusted analysis, costs were incrementally lower by an average of 5.4% per MET increase (p < 0.001). In a multivariable analysis adjusting for demographic variables, treadmill test performance and results, and clinical history, METs were found to be the most significant predictor of cost (F-statistic, 21.8; p < 0.001).

CONCLUSION

These findings are consistent with the hypothesis that exercise capacity is inversely associated with health-care costs.

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.

Prognostic value of exercise tests in male veterans with chronic coronary artery disease

PURPOSE

The authors evaluate the prognostic value of treadmill testing in a large consecutive series of patients with chronic coronary artery disease. Exercise testing is widely performed, but analyses of the prognostic value of test results have largely concentrated on patients referred for the diagnosis of coronary artery disease, patients after an acute coronary event or procedure, or patients with congestive heart failure.

METHODS

All patients referred for evaluation at two 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 using the Social Security Death Index after a mean 5.8-year follow-up. Patients without established heart disease and those with congestive heart failure were excluded, leaving the target population of those with a history myocardial infarction or coronary intervention. 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 used as the endpoint for follow-up. Standard survival analysis was performed including Kaplan Meier curves and the Cox Hazard Model.

RESULTS

Of the 1,473 patients with coronary artery disease who had exercise testing, 273 (19%) patients had a revascularization procedure (Revascularization group); 813 (55%) had a history of myocardial infarction, diagnostic Q waves (MI group), or both; and 387 (26%) had a history of myocardial infarction or Q wave and revascularization (Combined group). Mean age of the patients was 61.8 +/- 9 years. A total of 401 deaths occurred during a mean follow-up of 5.8 years with an annual mortality rate of 4.5%. Only two variables, age and maximal exercise capacity, were independently and statistically associated with time to death in all three groups and were the strongest predictors of all cause mortality.

CONCLUSION

A simple score based on METs, age, and history of myocardial infarction or diagnostic Q waves can stratify prognosis in patients with chronic coronary artery disease. The score enabled the identification of a group at low risk (32% of the cohort) with an annual mortality rate of 2%, a group at intermediate risk (42% of the cohort) with an annual mortality rate of about 4%, and a group at high risk (26% of the cohort) with an average annual mortality rate of approximately 7%.

The prognostic value of body mass index and standard exercise testing in male veterans with congestive heart failure

OBJECTIVE

To evaluate the prognostic characteristics of body mass index (BMI) and standard exercise test variables in a consecutive series of patients with mild to moderate congestive heart failure (CHF) referred for standard exercise tests.

BACKGROUND

Controversy exists regarding the prognostic importance of BMI, etiology, and exercise test variables in patients with CHF.

METHODS

All patients referred for evaluation at two university-affiliated Veterans Affairs Medical Centers who underwent treadmill tests for clinical indications between 1987 and 2000 were determined to be dead or alive using the Social Security Death Index after a mean 6 years 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. Survival analysis was performed using all-cause mortality as the endpoint for follow-up.

RESULTS

A total of 522 patients with a history and clinical findings of CHF underwent exercise testing. Forty-two percent died during the follow-up period, for an average annual mortality of 6.7%. Cox proportional hazards model chose peak metabolic equivalents (METs), BMI, age, and ischemic etiology in rank order as independently and significantly associated with time to death. A score based on these variables classified patients into low (2% annual mortality), medium (5.2%), and high-risk groups (7% annual mortality).

CONCLUSION

Standard exercise testing and BMI can be used to estimate prognosis in outpatients with heart failure. A score incorporating METs, BMI, age, and etiology efficiently stratified these patients. BMI was chosen by the survival analysis, confirming its surprising inverse relationship to prognosis in CHF patients (i.e., heavier patients do better).

Significance of ST-segment morphology noted on electrocardiography during the recovery phase after exercise in patients with ischemic heart disease as analyzed with simultaneous dual-isotope single photon emission tomography

BACKGROUND

The significance of differences in electrocardiographic morphology that occur during the recovery phase after exercise has not been clarified. We investigated the relationship between postexercise electrocardiographic morphology and the pattern of residual ischemia measured at that time.

METHODS

Exercise dual-isotope single photon emission computed tomography was performed on 171 consecutive patients with chest pain syndrome. After injection of technetium-99m tetrofosmin at peak exercise and thallium-201 at 3 minutes after exercise, dual-isotope single photon emission computed tomographic images were obtained simultaneously. After cross-talk compensation, the extent of ischemia and its localization were measured at both peak exercise and after exercise.

RESULTS

When 64 patients with angiographically and scintigraphically proven ischemic heart disease were grouped by morphology of ST-segment depressions at 3 minutes after exercise, 38 patients with the downsloping type had ischemia localized mainly to the middle and basal levels as compared with the more rapid resolution of ischemia in 12 patients with horizontal type and 14 patients with no ischemic electrocardiographic response (apical level 18.4% [7/38], 8.3% [1/12], and 0% [0/14], P = not significant, middle level 47.4% [18/38], 16.7% [2/12], and 7.1% [1/14], P <.01, basal level 57.9% [22/38], 33.3% [4/12], and 14.3% [2/14], P <.02, respectively) independent of the extent or localization of any ischemia noted during exercise (all levels, P = not significant).

CONCLUSION

Electrocardiographic morphology during the recovery phase of exercise reflects the extent and localization of residual ischemia at that time independent of ischemic changes noted during exercise.

The prognostic value of exercise testing in elderly men

PURPOSE

Our purposes were to compare the responses to exercise testing in elderly (> or =65 years of age) and younger men, and to investigate whether exercise testing has similar prognostic value in the two age groups.

METHODS

We included all elderly (n = 1185) and younger (n = 2789) male veterans without established coronary heart disease who underwent routine clinical exercise testing between 1987 and 2000 at two academically affiliated Veteran's Affairs medical center laboratories. Measurements included a standardized medical history, exercise testing, and all-cause mortality.

RESULTS

Compared with younger patients, elderly patients achieved a lower workload (a mean [+/- SD] of 7 +/- 3 vs. 10 +/- 4 metabolic equivalents [METs], P <0.001) and were more likely to have abnormal ST depression (27% [n = 324] vs. 16% [n = 436], P <0.001). During the mean follow-up of 6 years, annual mortality was twice as high among elderly patients as among younger patients (4% vs. 2%, P <0.001). The only exercise test variable that was associated significantly with time to death in both age groups was maximal METs achieved: each 1 MET increase in exercise capacity was associated with an 11% reduction in annual mortality. Exercise-induced ST depression was more common in those who subsequently died, but was not an independent predictor of mortality.

CONCLUSION

In elderly men, exercise testing provided prognostic information incremental to clinical data. Achieved workload (in METs) was the major exercise testing variable associated with all-cause mortality. Its prognostic importance was the same in elderly as in younger men.

Exercise capacity and mortality among men referred for exercise testing

BACKGROUND

Exercise capacity is known to be an important prognostic factor in patients with cardiovascular disease, but it is uncertain whether it predicts mortality equally well among healthy persons. There is also uncertainty regarding the predictive power of exercise capacity relative to other clinical and exercise-test variables.

METHODS

We studied a total of 6213 consecutive men referred for treadmill exercise testing for clinical reasons during a mean (+/-SD) of 6.2+/-3.7 years of follow-up. Subjects were classified into two groups: 3679 had an abnormal exercise-test result or a history of cardiovascular disease, or both, and 2534 had a normal exercise-test result and no history of cardiovascular disease. Overall mortality was the end point.

RESULTS

There were a total of 1256 deaths during the follow-up period, resulting in an average annual mortality of 2.6 percent. Men who died were older than those who survived and had a lower maximal heart rate, lower maximal systolic and diastolic blood pressure, and lower exercise capacity. After adjustment for age, the peak exercise capacity measured in metabolic equivalents (MET) was the strongest predictor of the risk of death among both normal subjects and those with cardiovascular disease. Absolute peak exercise capacity was a stronger predictor of the risk of death than the percentage of the age-predicted value achieved, and there was no interaction between the use or nonuse of beta-blockade and the predictive power of exercise capacity. Each 1-MET increase in exercise capacity conferred a 12 percent improvement in survival.

CONCLUSIONS

Exercise capacity is a more powerful predictor of mortality among men than other established risk factors for cardiovascular disease.

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.

Exercise-induced silent myocardial ischemia and coronary morbidity and mortality in middle-aged men

OBJECTIVES

We investigated the prognostic significance of exercise-induced silent myocardial ischemia in both high and low risk men with no prior coronary heart disease (CHD).

BACKGROUND

Silent ischemia predicts future coronary events in patients with CHD, but there is little evidence of its prognostic significance in subjects free of CHD.

METHODS

We investigated the association of silent ischemia, as defined by ST depression during and after maximal symptom-limited exercise test, with coronary risk in a population-based sample of men with no prior CHD followed for 10 years on average.

RESULTS

Silent ischemia during exercise was associated with a 5.9-fold (95% CI 2.3 to 11.8) CHD mortality in smokers, 3.8-fold (95% CI 1.9 to 7.9) in hypercholesterolemic men and 4.7-fold (95% CI 2.4 to 9.1) in hypertensive men adjusting for other risk factors. The respective relative risks (RRs) of any acute coronary event were 3.0 (95% CI 1.7 to 5.1), 1.9 (95% CI 1.2 to 3.1) and 2.2 (95% CI 1.4 to 3.5). These associations were weaker in men without these risk factors. Furthermore, silent ischemia after exercise was a stronger predictor for the risk of acute coronary events and CHD death in smokers and in hypercholesterolemic and hypertensive men than in men without risk factors.

CONCLUSIONS

Exercise-induced silent myocardial ischemia was a strong predictor of CHD in men with any conventional risk factor, emphasizing the importance of exercise testing to identify asymptomatic high risk men who could benefit from risk reduction and preventive measures.

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.

A knowledge-based technique for automated detection of ischaemic episodes in long duration electrocardiograms

A novel method for the detection of ischaemic episodes in long duration ECGs is proposed. It includes noise handling, feature extraction, rule-based beat classification, sliding window classification and ischaemic episode identification, all integrated in a four-stage procedure. It can be executed in real time and is able to provide explanations for the diagnostic decisions obtained. The method was tested on the ESC ST-T database and high scores were obtained for both sensitivity and positive predictive accuracy (93.8% and 78.5% respectively using aggregate gross statistics, and 90.7% and 80.7% using aggregate average statistics).

Exercise stress testing. An overview of current guidelines

Exercise stress testing (ET) is an inexpensive noninvasive tool that provides valuable cardiopulmonary information in healthy and diseased populations. It is most commonly used for diagnosing coronary artery disease (CAD) and developing appropriate exercise prescriptions (EP). With its widespread use and application, it is imperative that safe and appropriate guidelines and procedures are used, as there are a number of risks associated with testing in a population with or suspected of having CAD. The focus should be on the patient's safety: personnel must be properly trained and aware of all emergency procedures, contra-indications for ET and indications for test termination must be strictly adhered to. Three main types of testing are prevalent: submaximal, maximal and maximal utilising gas exchange. The maximal test is most commonly used, and the submaximal is appropriate for hospitalised patients. Gas exchange data is essential when assessing congestive heart failure and timing for heart transplantation. ET is commonly performed using a treadmill or a bicycle ergometer. The treadmill provides a more familiar exercise modality and has been shown to have greater diagnostic sensitivity than the bicycle ergometer; it is, however, more expensive and requires more space in the testing room. The bicycle ergometer is more appropriate for those individuals who are severely obese or have problems with extended periods of walking. Regardless of the modality used, an appropriate exercise protocol should be used. In North America, the Bruce protocol is the most common. However, the Bruce protocol, and others that estimate exercise capacity based on equations, tend to overestimate exercise capacity. They may be too demanding for those with limited exercise capacity, and too long for those with high exercise capacity. For these people, an exercise protocol that reaches maximal capacity in 8 to 12 minutes using smaller increments in workload should be considered. Once completed, the results of ET needs to be correctly interpreted. This includes reviewing the test results while considering the patient's history, medications and indication for the test. ET can also be used to develop an EP for the participant. An EP should take into account the intensity, modality of exercise, frequency and duration, as well as being realistic for the individual and the goals to be achieved. All the information from the test results and the pre-test examination should be presented in a report that also includes the advised EP.

Can computerization of the exercise test replace the cardiologist?

BACKGROUND

The type of practitioners who use the standard exercise test is changing. Once a tool of the cardiologist, the standard exercise test is now being performed by internists and other noncardiologists. Because this change could be facilitated by computerization similar to the computerized interpretation programs available for the resting electrocardiograph (ECG), we performed this analysis. A secondary aim was to demonstrate the effects of medication status and resting ECG abnormalities on test diagnostic characteristics because these factors affect utility of the exercise test by the generalist.

METHODS AND RESULTS

A retrospective analysis was performed of consecutive patients referred at 2 university-affiliated Veteran's Affairs Medical Centers and a Hungarian Hospital for evaluation of chest pain and possible ischemic heart disease. There were 1384 consecutive male patients without a prior myocardial infarction with complete data who had exercise tests and coronary angiography between 1987 and 1997. Measurements included clinical, exercise test data, and visual interpretation of the ECG recordings as well as more than 100 computed measurements from the digitized ECG recordings and compilation of angiographic data from clinical reports. The computer measurements had similar diagnostic power compared with visual interpretation. Computerized measurements from maximal exercise or recovery were equivalent or superior to all other measurements. Prediction equations applied by computer were superior to single ECG measurements. Beta-blockers had no effect on test characteristics, whereas resting ST depression was associated with decreased specificity and increased sensitivity.

CONCLUSIONS

Computerized exercise ST measurements are comparable to visual ST measurements by a cardiologist; computerized scores that included clinical and exercise test results exhibited the greatest diagnostic power. Applying scores with a computer allows the practicing physician to improve the diagnostic characteristics of the standard exercise test. This approach is successful even when there is resting ST depression, thus lessening the need for more expensive nuclear or imaging studies.

Effect of coronary collateral circulation on exercise stress test

In this study, patients who have recovery-only ST segment depression in exercise stress test were chosen. It is proposed that coronary collateral circulation could improve with stress-increased coronary perfusion, and accordingly, patients with recovery-only ST segment depression were evaluated by coronary angiography for grading the coronary collateral circulation. Twenty-one men and five women were assigned to the study group. Sixteen men and two women who had exercise-induced ST segment depression were assigned to the control group. Age and gender of both groups were not statistically different (p>0.05). The reason for terminating the exercise stress test was chest pain in two of 26 patients in the study group versus 15 of 18 in the control group (p<0.001). In both groups coronary collateral frequency and grade were directly correlated with the severity of the coronary artery disease (p<0.001 in the study group, and p<0.05 in the control group). When both groups were compared for the frequency of significant coronary collateral circulation, 14 of 26 patients in the study group versus 4 of 18 patients in the control group had significant coronary collateral circulation (p=0.035). The authors conclude that recovery-only ST segment depression correlates well with the frequency of significant coronary collateral circulation, and coronary collaterals may prevent myocardial ischemia during exercise.

Independent prognostic significance of ischemic ST-segment response limited to recovery from treadmill exercise in asymptomatic subjects

BACKGROUND

Although exercise-induced ST depression is an independent predictor of future coronary events in asymptomatic populations, the predictive value of ST depression beginning after exercise cessation is unknown.

METHODS AND RESULTS

We analyzed the treadmill exercise tests of 825 healthy volunteers who were 22 to 89 years of age from the Baltimore Longitudinal Study of Aging. All subjects were free from coronary heart disease by history, physical examination, and resting ECG. From 825 participants, 611 (group 0) had no ischemic ST-segment changes during or after treadmill exercise, while 214 subjects developed > or = 1-mm flat or downsloping ST depression: 151 (group 1) had ST changes starting during exercise, and 63 (group 2) had changes limited to recovery. Groups 1 and 2 were similar in age, sex, smoking status, hypertension prevalence, fasting plasma glucose, and serum cholesterol (CHOL). However, both groups were older and had higher CHOL and prevalence of hypertension than group 0. Treadmill exercise duration, peak oxygen consumption, and maximal heart rate were similar between groups 1 and 2 but were lower than in group 0 (each P < 0.05). During a mean follow-up time of 9 years, 55 subjects developed coronary events (angina pectoris, myocardial infarction, or coronary death): 21 of 611 (3.4%) in group 0, 22 of 151 (14.6%) in group 1, and 12 of 63 (19%) in group 2 (P = 0.001). By survival analysis, the risk of coronary events was similar in groups 1 and 2 but significantly higher than in group 0 (P < 0.0001). Multiple logistic regression showed that age (odds ratio [OR] = 1.07 per year, P = 0.00001), CHOL (OR = 1.02 per 1 mg, P = 0.0001), and presence of ST-segment depression (OR = 2.59, P = 0.007 and OR = 2.38, P = 0.04 for groups 1 and 2, respectively) were independent predictors of events.

CONCLUSIONS

Thus, ischemic ST-segment changes developing during recovery from treadmill exercise in apparently healthy individuals have adverse prognostic significance similar to those appearing during exercise.

The effect of lead selection on traditional and heart rate-adjusted ST segment analysis in the detection of coronary artery disease during exercise testing

Several methods of heart rate-adjusted ST segment (ST/HR) analysis have been suggested to improve the diagnostic accuracy of exercise electrocardiography in the identification of coronary artery disease compared with traditional ST segment analysis. However, no comprehensive comparison of these methods on a lead-by-lead basis in all 12 electrocardiographic leads has been reported. This article compares the diagnostic performances of ST/HR hysteresis, ST/HR index, ST segment depression 3 minutes after recovery from exercise, and ST segment depression at peak exercise in a study population of 128 patients with angiographically proved coronary artery disease and 189 patients with a low likelihood of the disease. The methods were determined in each lead of the Mason-Likar modification of the standard 12-lead exercise electrocardiogram for each patient. The ST/HR hysteresis, ST/HR index, ST segment depression 3 minutes after recovery from exercise, and ST segment depression at peak exercise achieved more than 85% area under the receiver-operating characteristic curve in nine, none, three, and one of the 12 standard leads, respectively. The diagnostic performance of ST/HR hysteresis was significantly superior in each lead, with the exception of leads a VL and V1. Examination of individual leads in each study method revealed the high diagnostic performance of leads I and -aVR, indicating that the importance of these leads has been undervalued. In conclusion, the results indicate that when traditional ST segment analysis is used for the detection of coronary artery disease, more attention should be paid to the leads chosen for analysis, and lead-specific cut points should be applied. On the other hand, ST/HR hysteresis, which integrates the ST/HR depression of the exercise and recovery phases, seems to be relatively insensitive to the lead selection and significantly increases the diagnostic performance of exercise electrocardiography in the detection of coronary artery disease.

Accurate detection of coronary artery disease by integrated analysis of the ST-segment depression/heart rate patterns during the exercise and recovery phases of the exercise electrocardiography test

In this comparative cross-sectional study, we evaluated whether a novel computerized diagnostic variable, ST-segment depression/heart rate ST/HR analysis during both the exercise and postexercise recovery phases of the exercise electrocardiography (ECG) test, can detect coronary artery disease more accurately than methods using either exercise or recovery phase alone. The study population comprised 347 clinical patients referred for a routine bicycle exercise ECG test at Tampere University Hospital, Finland. Of these, 127 had angiographically proven coronary artery disease, whereas 13 had no coronary artery disease according to angiography, 18 had no perfusion defect according to technetium-99m sestamibi single-photon emission computed tomography, and 189 were clinically normal with respect to cardiac diseases. For each patient, the maximum values of the ST/HR hysteresis, ST/HR index, end-exercise ST depression, and recovery ST depression were determined from the Mason-Likar modification of the standard 12-lead exercise electrocardiogram [aVL, aVR, and V1 excluded]. The diagnostic performance of these continuous diagnostic variables was compared by means of receiver-operating characteristic analysis. The area under the receiver-operating characteristic curve of the ST/HR hysteresis was 89%, which was significantly larger than that of the end-exercise ST depression (76%, p < or = 0.0001), recovery ST depression (84%, p = 0.0063), or ST/HR index (83%, p = 0.0023), indicating superior diagnostic performance of the ST/HR hysteresis independent of the partition value selection. In conclusion, computerized analysis of the HR-adjusted ST depression pattern during the exercise phase, integrated with the HR-adjusted ST depression pattern during the recovery phase after exercise, can significantly improve the diagnostic performance and clinical utility of the exercise ECG test for the detection of coronary artery disease.

Prediction of atherosclerotic cardiovascular death in men using a prognostic score

Treadmill and clinical data were gathered prospectively on consecutive patients who underwent exercise testing for evaluation for coronary artery disease in a 1,200 bed Veterans Affairs Medical Center. From 3,609 men referred for exercise testing from 1984 to 1990, 3,134 patients remained after excluding those with significant valvular heart disease and those with prior coronary artery bypass surgery. Of these, 588 were selected for clinical reasons to undergo cardiac catheterization within 3 months of evaluation leaving 2,546 who were not selected. Over 3 years, there were 158 cardiovascular deaths, 99 nonfatal myocardial infarcts and 183 patients who underwent coronary artery bypass surgery. In the total population, the Cox proportional-hazards model demonstrated the following characteristics to be statistically significant independent predictors of time until cardiovascular death: a history of congestive heart failure and/or taking digoxin, exercise-induced ST depression, the change in systolic blood pressure during exercise, and exercise capacity in METs. Using the Cox model coefficients to weight the variables, a simple score (the Veterans Affairs Prognostic Score) was constructed based on these items. Average annual cardiovascular mortality was plotted against the score enabling its estimation for any given patient. In the subgroup selected for cardiac catheterization (n = 588), the mean score was greater, consistent with a poorer prognosis, compared with the total population; 53% (n = 312) had a score < -2 associated with an annual mortality < 2%. Thus, in over half of the patients selected for catheterization, the catheterization was unnecessary if performed to lessen their chance of cardiovascular death, since no intervention could improve their prognosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Prediction of cardiovascular death by means of clinical and exercise test variables in patients selected for cardiac catheterization

The objective of this report is the development of a population-specific prediction rule based on clinical and exercise test data that would estimate the risk of cardiovascular death in patients selected for cardiac catheterization. Prospective data and follow-up information were obtained from patients who underwent cardiac catheterization soon after clinical assessment and exercise testing. Males (n = 588) referred for evaluation of coronary heart disease from 1984 to 1990 were selected after exclusion of patients with significant valvular heart disease and patients with prior cardiac surgery. Half had a prior myocardial infarction and half complained of typical angina pectoris. All patients performed a treadmill test and were selected for clinical reasons to undergo coronary angiography within 3 months. Over a mean follow-up period of 2.5 years (+/- 1.4 years), there were 39 cardiovascular deaths and 45 nonfatal myocardial infarctions. The Cox proportional hazards model demonstrated the following characteristics to be statistically significant independent predictors of time until cardiovascular death: history of congestive heart failure (hazards ratio of 4), ST depression on the resting ECG (hazards ratio of 3), and a drop in systolic blood pressure below the resting value during exercise (hazards ratio of 5). Exercise-induced ST depression was not associated with either death or nonfatal myocardial infarction. A simple score based on one item of clinical information (history of congestive heart failure), a resting ECG finding (ST depression), and an exercise test response (exertional hypotension) stratified our patients for 4 years after testing from 75% with a low risk (annual cardiac mortality rate of 1%), 17% with a moderate risk (annual mortality rate of 7%), and 1% with a high risk (annual cardiac mortality rate of 12%, with a hazards ratio of 20 and 95% confidence interval from 6 to 70X). It was concluded that the variables available from the usual noninvasive workup of patients with known or suspected coronary artery disease enable prediction of risk of cardiovascular death. Three quarters of those usually undergoing cardiac catheterization can be identified by simple noninvasive variables as being at such low risk that invasive intervention is unlikely to improve prognosis.

Comparison of computer ST criteria for diagnosis of severe coronary artery disease

To determine which computer ST criteria are superior for predicting patterns and severity of coronary artery disease during exercise testing, 230 male veterans were studied who had both coronary angiography and a treadmill exercise test. Significant (p < or = 0.05) differences in computer-scored ST criteria were observed among patients with progressively increasing disease severity. Three-vessel/left main disease produced responses significantly different from 1- and 2-vessel disease or those with < 70% occlusion. Discriminant function analysis revealed that horizontal or downsloping ST depression measured at the J junction during exercise or recovery, or both, was the most powerful predictor of severe disease. With use of a cut point of 0.075 mV ST depression, horizontal or downsloping ST depression alone yielded a sensitivity of 50% (95% confidence interval = 35 to 65%) and specificity of 71% for prediction of severe disease; the only additional variable that added significantly to the prediction was exercise capacity, which improved sensitivity to 57% (95% confidence interval = 41 to 72%) with no change in specificity. Measurements of ST amplitude at the J junction and at 60 ms after the J point without slope considered and other scores, including the Treadmill Exercise Score, ST Integral, and ST/heart rate index, had a lower but comparable predictive accuracy when compared with horizontal or downsloping ST depression. Prediction of coronary artery disease severity can be achieved using computerized electrocardiographic measurements obtained during exercise testing. The most powerful marker for severe coronary artery disease is the amount of horizontal or downsloping ST-segment depression during exercise or recovery, or both, a measurement that stimulates the traditional visual approach.

The importance of assessing time-course behaviour of abnormal ST/T changes after exercise

Routine stress electrocardiography has been criticised for yielding too many so-called 'false-positive' results because ST/T changes that develop during and after exercise are prevalent. Recent studies in our institution indicate, however, that the time-course behaviour patterns of these ST/T configurational 'abnormalities' after exercise are different from those reflecting myocardial ischaemia due to epicardial coronary artery disease (CAD). Time-course analysis increases the predictive value of exercise testing and has dramatically decreased the number of asymptomatic subjects or symptomatic patients at low risk of having CAD being subjected to coronary arteriography in our institution. Our method of assessing post-exercise time course patterns of abnormal ST/T are described in detail. Ischaemic ST/T abnormalities have late onset, early offset or early onset, late offset whereas those ST/T changes associated with normal epicardial coronary arteries have late onset, late offset or early onset, early offset post-exercise time course patterns.

Exercise-induced ST depression and ST/heart rate index to predict triple-vessel or left main coronary disease: a multicenter analysis

The aim of this investigation was to determine the difference in accuracy between two frequently published noninvasive indicators of severity of coronary artery disease (exercise-induced ST segment depression and heart rate-adjusted ST depression [ST/HR index]). The study was designed as a survey of consecutive patients undergoing exercise electrocardiography and coronary angiography. There were a total of 2,270 patients without prior myocardial infarction or cardiac valvular disease referred for angiography from eight institutions in three countries; 401 of these patients had triple-vessel or left main coronary artery disease. The sensitivities of ST depression and ST/HR index in detecting triple-vessel or left main coronary artery disease were, respectively, 75% and 78% (p = 0.08) at cut point values where their specificities were equal (64%). This small increase in the accuracy of the ST/HR index was evident only at peak exercise heart rates below the median value of 132 beats/min, where the sensitivities of ST depression and ST/HR index were 73% and 76% (p = 0.03), respectively, at cut point values corresponding to a specificity of 60%. These results were consistent at all eight participating institutions. The increase in accuracy achieved by dividing exercise-induced ST depression by heart rate is small and confined exclusively to a low exercise heart rate. This lack of superiority cannot be generalized to all methods of heart rate adjustment.

Prediction of severe coronary artery disease using computerized ECG measurements and discriminant function analysis

This study tested the hypothesis that discriminant function analysis of clinical and exercise-test variables including computerized ST measurements could improve the prediction of severe coronary artery disease. Secondary objectives were to demonstrate the effect of digoxin and/or resting electrocardiographic (ECG) abnormalities, and to evaluate the relative importance of ST measurements made during the recovery phase and in the three lead group areas. The design was a retrospective analysis of data collected during exercise testing and coronary angiography. The ECG data were gathered and stored in digital format on optical discs and all ST measurements were made off-line using the authors' own software. Univariate and multivariate analytic methods were used to analyze all pretest characteristics as well as hemodynamic and computerized ECG responses to exercise. A 1,000-bed Veterans Affairs Medical Center served as the setting. The study included 446 male veterans who underwent a sign or symptom limited treadmill exercise test and coronary angiography. Analysis was also performed on a subset of this population formed by excluding patients receiving digoxin or with resting ECGs exhibiting left ventricular hypertrophy or ST depression (n = 328). In the total study population, the authors derived a treadmill score using discriminant function analysis. This score included: (1) the time-slope area in lead V5 during recovery; (2) delta heart rate; (3) angina pectoris during the exercise test; and (4) presence of diagnostic Q waves on the resting ECG. This score was effective in predicting triple vessel/left main disease and outperformed exercise-induced ST depression for predicting severe coronary artery disease. After exclusion of patients with ECGs exhibiting left ventricular hypertrophy or resting ST depression and patients receiving digoxin, discriminant function analysis chose: (1) the time-slope area in lead V5 during recovery and (2) delta heart rate. Exclusion of these patients resulted in a nonsignificant decrease in specificity of all ST criteria. ST-segment amplitude or slope in lead V5 at 3.5 minutes in recovery clearly outperformed the maximal exercise measurements in both groups. Summing the depressions or selecting the most depression in the three areas (ie, lateral-V5, inferior-II, anterior-V2) did not improve test performance. Leads other than V5 did not contain significant diagnostic information. A quantitative approach to exercise testing using discriminant function analysis enhanced the tests' performance for predicting severe coronary disease. The inclusion of patients taking digoxin or with resting ECG abnormalities nonsignificantly decreases the specificity of all ST criteria.(ABSTRACT TRUNCATED AT 400 WORDS)