Prognostic value of the duke treadmill score in asymptomatic women

Stress Electrocardiography Testing in Coronary Artery Disease: Is It Time for Its Swan Song or To Redefine Its Role in the Modern Era ?

Stress electrocardiography (sECG) or treadmill stress testing is a well validated noninvasive diagnostic modality available to clinicians at low cost yet providing valuable functional data for coronary artery disease (CAD) diagnostic and prognostic evaluation. With the advances in cardiac imaging in both functional and anatomic fronts and the existing limitations of sECG testing, this modality appears less favored worldwide as reflected in some recent guideline updates. We review the past present and future of sECG to provide a viewpoint on where it stands in CAD evaluation and if it will remain relevant as a diagnostic modality or be retired going forward. We also provide our perspectives on how sECG can co-exist with other modalities such as calcium scoring and discuss the role of such testing in the Indian population.

The importance of stratifying ischemic risk by using the Duke score in women with ischemic heart disease and hypothyroidism before inclusion in cardiovascular rehabilitation programs

Introduction: The relationship between abnormal thyroid function and coronary heart disease has been known for a long time, and particularly, hypothyroidism is associated with an increased risk of cardiovascular disease. The aim of this study was to evaluate the ischemic risk by using the Duke score in women with ischemic heart disease and associated hypothyroidism before inclusion in cardiovascular rehabilitation program. Materials and methods: We included in the study 150 female patients admitted to the Cardiology Department of the Clinical Rehabilitation Hospital Cluj-Napoca. All the patients included had ischemic heart disease and performed an exercise stress testing to evaluate the effort capacity and also to stratify the ischemic risk by calculating the Duke Score. After dosing the thyroid stimulating hormone (TSH) we divided the patients in two groups: with hypothyroidism and a control group. Results: Patients with hypothyroidism were more frequently hypertensive, (98% vs 87%, p-0.035), and they had diabetes mellitus in a higher proportion (51% vs 22%, p-0.005). HDL cholesterol was significantly decreased in the group of patients with hypothyroidism: 40.36±10.39mg/dl vs 44.85±10.29mg/dl (p-0.01). Regarding the ischemic risk assessed by the Duke score, the statistically significant differences between the two groups were registered only for the category of high-risk patients, 5.55% vs 18% (p-0.048). Also, the TSH value was higher in the group with high-risk Duke score, 4.21±3.73µIU/ml, compared to the moderate-risk score group, 1.95±1.12µIU/ml(p-0.05). Conclusion: In women with ischemic heart disease, assessing thyroid function can be useful to identify patients at high risk of ischemia. Patients with hypothyroidism tend to have a higher prevalence of cardiovascular risk factors, a higher ischemic risk objectified by the Duke score and more commonly multivascular coronary lesions. For these patients, the inclusion in cardiovascular rehabilitation programs is essential, but it is very important that the programs to be customized for each patient. Keywords: coronary heart disease in women, exercise ECG, Duke score, ischemic risk, hypothyroidism, cardiovascular rehabilitation programs

Relationship of Cardiorespiratory Fitness and Body Mass Index with the Incidence of Dyslipidemia among Japanese Women: A Cohort Study

Low cardiorespiratory fitness (CRF) and obesity are independent risk factors for dyslipidemia. We investigated the synergistic effects of CRF and obesity on the incidence of dyslipidemia among Japanese women. Of 7627 participants, 927 normolipidemic Japanese women completed a submaximal exercise test, medical examination, and a questionnaire on smoking and alcohol drinking. The incidence of dyslipidemia was defined as having at least one of the following: high-density lipoprotein cholesterol < 40 mg/dL, low-density lipoprotein cholesterol ≥ 140 mg/dL, fasting triglyceride ≥ 150 mg/dL, or physician-diagnosed dyslipidemia. Multivariable hazard ratios (HRs) and 95% confidence intervals (CI) were calculated using a Cox proportional hazard regression model. During the follow-up period of ≤16 years (median 1 year), 196 (21.1%) women developed dyslipidemia. Compared with those in the body mass index (BMI)-specific (< or ≥25.0 kg/m²) lowest CRF tertile, the multivariable HRs for dyslipidemia in the highest CRF tertile were 1.36 (95% CI, 0.75–2.48) for women with BMI ≥ 25 kg/m² and 0.70 (95% CI, 0.45–1.09) for those with BMI < 25 kg/m² (p < 0.01 for interaction). These results suggest that CRF and BMI are interdependent and, together, they affect the incidence of dyslipidemia among Japanese women. CRF is inversely related to a lower incidence of dyslipidemia with low BMI.

Imaging to Stratify Coronary Artery Disease Risk in Asymptomatic Patients with Diabetes

Coronary artery disease (CAD) is the leading cause of morbidity and mortality in patients with diabetes mellitus. Patients with diabetes have a higher prevalence of CAD and a larger magnitude of ischemia, and they are more likely to have silent myocardial ischemia and myocardial infarction. However, recent large cohort studies demonstrate that diabetic patients are not a homogenous group with similar high risk for cardiac events. In fact, more than 30% of asymptomatic diabetic patients do not have evidence of coronary atherosclerosis and have a very low annual cardiac event rate. Accordingly, there has been a recent paradigm shift as to whether the detection of subclinical coronary atherosclerosis through imaging can best guide therapeutic decision making. This review discusses the role of various cardiac imaging techniques for stratifying cardiovascular risk and optimizing therapy in asymptomatic diabetic patients.

False-positive stress testing: Does endothelial vascular dysfunction contribute to ST-segment depression in women? A pilot study

BACKGROUND

The utility of exercise-induced ST-segment depression for diagnosing ischemic heart disease (IHD) in women is unclear.

HYPOTHESIS

Based on evidence that IHD pathophysiology in women involves coronary vascular dysfunction, we hypothesized that coronary vascular dysfunction contributes to exercise electrocardiography (Ex-ECG) ST-depression in the absence of obstructive coronary artery disease, so-called false positive results. We tested our hypothesis in a pilot study evaluating the relationship between peripheral vascular endothelial function and Ex-ECG.

METHODS

Twenty-nine asymptomatic women without cardiac risk factors underwent maximal Bruce protocol exercise treadmill testing and peripheral endothelial function assessment using peripheral arterial tonometry (Itamar EndoPAT 2000) to measure reactive hyperemia index (RHI). The relationship between RHI and Ex-ECG ST-segment depression was evaluated using logistic regression and differences in subgroups using 2-tailed t tests.

RESULTS

Mean age was 54 ± 7 years, body mass index 25 ± 4 kg/m² , and RHI 2.51 ± 0.66. Three women (10%) had RHI <1.68, consistent with abnormal peripheral endothelial function, whereas 18 women (62%) met criteria for positive Ex-ECG based on ST-segment depression in contiguous leads. Women with and without ST-segment depression had similar baseline and exercise vital signs, metabolic equivalents achieved, and RHI (all P > 0.05). RHI did not predict ST-segment depression.

CONCLUSIONS

Our pilot study demonstrates high prevalence of exercise-induced ST-segment depression in asymptomatic, middle-aged, overweight women. Peripheral vascular endothelial dysfunction did not predict Ex-ECG ST-segment depression. Further work is needed to investigate the utility of vascular endothelial testing and Ex-ECG for IHD diagnostic and management purposes in women.

Stable ischemic heart disease in women: current perspectives

Cardiovascular disease is the leading cause of death in women accounting for 1 in every 4 female deaths. Pathophysiology of ischemic heart disease in women includes epicardial coronary artery, endothelial dysfunction, coronary vasospasm, plaque erosion and spontaneous coronary artery dissection. Angina is the most common presentation of stable ischemic heart disease (SIHD) in women. Risk factors for SIHD include traditional risks such as older age, obesity (body mass index [BMI] >25 kg/m²), smoking, hypertension, dyslipidemia, cerebrovascular and peripheral vascular disease, sedentary lifestyle, family history of premature coronary artery disease, metabolic syndrome and diabetes mellitus, and nontraditional risk factors, such as gestational diabetes, insulin resistance/polycystic ovarian disease, pregnancy-induced hypertension, pre-eclampsia, eclampsia, menopause, mental stress and autoimmune diseases. Diagnostic testing can be used effectively to risk stratify women. Guidelines-directed medical therapy including aspirin, statins, beta-blocker therapy, calcium channel blockers and ranolazine should be instituted for symptom and ischemia management. Despite robust evidence regarding the adverse outcomes seen in women with ischemic heart disease, knowledge gaps exist in several areas. Future research needs to be directed toward a greater understanding of the role of nontraditional risk factors for SIHD in women, gaining deeper insights into the sex differences in therapeutic effects and formulating a sex-specific algorithm for the management of SIHD in women.

Utility of Imaging in Risk Stratification of Chest Pain in Women

OPINION STATEMENT

Recent decades have seen a growing recognition that the understanding of sex differences in cardiovascular disease (CVD) is vital to optimal diagnosis and management, particularly of women (Mosca et al. Circulation 124:2145-54, 2011). There is simultaneously an increasing appreciation of the multifactorial nature of ischemic heart disease (IHD) in many patients, in whom disease may extend beyond the epicardial coronaries. While obstructive coronary artery disease (CAD) remains underdiagnosed in women and still represents a major burden of disease, women also present with nonobstructive CAD more commonly than men (Patel et al. N Engl J Med 362:886-95, 2010). Indeed, microvascular dysfunction, coronary artery vasospasm, and coronary dissections contribute to a larger proportion of IHD in women than men (Bairey Merz et al. J Am Coll Cardiol 47:S21-9, 2006). Here, we review the symptom presentation of women with IHD and the noninvasive modalities used to risk stratify women with suspected IHD.

The role of treadmill exercise testing in women

Treadmill exercise electrocardiogram (ECG) is one of the most commonly used noninvasive tests for the assessment of ischemic heart disease (IHD). Sex-specific challenges in diagnostic and prognostic tests methods for IHD outlined the importance of pretest probability evaluation and referral bias using risk-prediction charts available for both asymptomatic and symptomatic women. Accordingly, exercise ECG has been indicated as the initial test for the symptomatic women at intermediate risk of IHD who has a normal resting ECG and is capable of maximal exercise. However, the difficulties of using exercise testing for diagnosing IHD in women have led to an initial speculation that stress imaging may be preferred to standard stress testing. This editorial analyzed a large body of evidence on the diagnostic and prognostic powers of treadmill ECG and exercise myocardial perfusion imaging (MPI) according to new advanced imaging technologies.

Maximal exercise testing variables and 10-year survival: fitness risk score derivation from the FIT Project

OBJECTIVE

To determine which routinely collected exercise test variables most strongly correlate with survival and to derive a fitness risk score that can be used to predict 10-year survival.

PATIENTS AND METHODS

This was a retrospective cohort study of 58,020 adults aged 18 to 96 years who were free of established heart disease and were referred for an exercise stress test from January 1, 1991, through May 31, 2009. Demographic, clinical, exercise, and mortality data were collected on all patients as part of the Henry Ford ExercIse Testing (FIT) Project. Cox proportional hazards models were used to identify exercise test variables most predictive of survival. A "FIT Treadmill Score" was then derived from the β coefficients of the model with the highest survival discrimination.

RESULTS

The median age of the 58,020 participants was 53 years (interquartile range, 45-62 years), and 28,201 (49%) were female. Over a median of 10 years (interquartile range, 8-14 years), 6456 patients (11%) died. After age and sex, peak metabolic equivalents of task and percentage of maximum predicted heart rate achieved were most highly predictive of survival (P<.001). Subsequent addition of baseline blood pressure and heart rate, change in vital signs, double product, and risk factor data did not further improve survival discrimination. The FIT Treadmill Score, calculated as [percentage of maximum predicted heart rate + 12(metabolic equivalents of task) - 4(age) + 43 if female], ranged from -200 to 200 across the cohort, was near normally distributed, and was found to be highly predictive of 10-year survival (Harrell C statistic, 0.811).

CONCLUSION

The FIT Treadmill Score is easily attainable from any standard exercise test and translates basic treadmill performance measures into a fitness-related mortality risk score. The FIT Treadmill Score should be validated in external populations.

Role of echocardiography in the management of cardiac disease in women

The widespread use of echocardiography has contributed to the early recognition of several distinct cardiac diseases in women. During pregnancy, safe monitoring of the disease process, as well as a better understanding of hemodynamics, is possible. During the use of potentially cardiotoxic drugs for breast cancer chemotherapy, echocardiographic patient monitoring is vital. Compared to men, the addition of an imaging modality to routine electrocardiogram monitoring during stress testing is more informative for diagnosing coronary disease in women. This review briefly discusses the role of echocardiography in the management of several women-specific cardiac diseases where echocardiography plays a pivotal role in disease management.

QT hysteresis index improves the power of treadmill exercise test in the screening of coronary artery disease

BACKGROUND

QT hysteresis phenomenon exists in healthy subjects, and is more exaggerated in patients with coronary artery disease (CAD) and long QT syndrome. The purpose of this study was to establish an appropriate method to evaluate the magnitude of QT hysteresis, and assess the value of QT hysteresis index in the treadmill exercise test (TET) in predicting CAD. METHODS AND RESULTS: A total of 138 subjects with suspected CAD and referred for TET and selective coronary angiography (SCA) were divided into positive (n=77) and negative (n=61) SCA groups. Dynamic ECG were recorded during TET. QT/RR curves were constructed and QTp (Q-Tpeak) and QTe (Q-Tend) hysteresis indices were calculated for each subject. SYNTAX score in the positive SCA group was determined. The QTp and QTe hysteresis indices in the positive SCA group were significantly higher than in the negative SCA group. The combination of QTe hysteresis index and conventional TET criteria had the highest sensitivity and negative predictive value according to receiver operating characteristic curve, and was an independent predictor on multivariate logistic regression. QT hysteresis indices significantly correlated with SYNTAX score in the positive SCA group.

CONCLUSIONS

QTe hysteresis index enhances the specificity of predicting CAD in TET. It improves the diagnostic value of TET for CAD significantly when combined with conventional criteria and is associated with the severity of CAD.

Incremental value of objective cardiac testing in addition to physician impression and serial contemporary troponin measurements in women

OBJECTIVES

Guidelines recommend that patients presenting to the emergency department (ED) with chest pain who are at low risk for acute coronary syndrome (ACS) receive an objective cardiac evaluation with a stress test or coronary imaging. It is uncertain whether all women derive benefit from this process. The study aim was to determine the incremental value of objective cardiac testing after serial cardiac markers and physician risk assessment.

METHODS

Women enrolled in the 18-site Myeloperoxidase in the Diagnosis of Acute Coronary Syndrome (MIDAS) study had serial troponin I measured at time 0 and 90 minutes and physician risk assessment for the presence of ACS. Risk estimates obtained at the time of ED evaluation were dichotomized as high or non-high risk. The primary outcome was the composite of acute myocardial infarction (AMI) or revascularization at 30 days. Logistic regression with receiver operator characteristic (ROC) curves and net reclassification index were used to determine the diagnostic accuracy for the composite outcome of 30-day MI or revascularization for two models: 1) troponin I results and physician risk assessment alone and 2) troponin I results, physician risk assessment, and objective cardiac testing.

RESULTS

A total of 460 women with a median age 58 years (interquartile range [IQR] = 48.5 to 68 years) were included, and 32 (6.9%) experienced AMI or revascularization by 30 days. Comparison of the area under the ROC curves (AUC) showed that the addition of objective cardiac testing to the combination of troponin I results and physician risk assessment did not significantly improve prediction of 30-day AMI or revascularization (AUC = 0.85 vs. 0.89; p = .053). Using a threshold of 1%, net reclassification index showed that the addition of objective cardiac testing to troponin I results and physician risk assessment worsened the prediction for 30-day AMI and revascularization. All of the reclassified patients were false positives, with nine (2.1%) patients incorrectly reclassified from <1% risk to ≥ 1% risk of 30-day AMI or revascularization.

CONCLUSIONS

In the era of contemporary troponin assays, objective cardiac testing after an ED clinician risk assessment of non-high risk and negative troponin I results at 0 and 90 minutes does not improve the prediction of 30-day AMI or revascularization in women presenting with chest pain or other symptoms of cardiac ischemia.

An update on exercise stress testing

Exercise stress testing is the most commonly used noninvasive method to evaluate for coronary artery disease in men and women. Although emphasis has been placed on the diagnostic value of ST-segment depression, the exercise stress test provides other valuable diagnostic and prognostic data, beyond ST-segment depression. The value of these variables, which include exercise capacity, chronotropic response, heart rate recovery, blood pressure response, and the Duke Treadmill Score, are reviewed in this article. In addition, the gender differences seen with these exercise testing variables are reviewed. In this modern era of exercise stress testing, making use of all the information from a stress test and creating a comprehensive stress testing report are recommended in the evaluation of patients with suspected coronary artery disease who undergo exercise stress testing.

Triple vessel coronary artery disease presenting as a markedly positive stress electrocardiographic test and a negative SPECT-TL scintigram: a case of balanced ischemia

The presence of false negative nuclear stress test in the settings of positive electrocardiographic changes is a very unusual phenomenon and is usually secondary to balanced ischemia of the myocardial segments evaluated by SPECT-TL. We present a case of an 81-year old post-menopausal female who presented to her primary care physician for evaluation of a 6-week dyspnea on exertion and was referred to our institution for exercise stress test with Thallium SPECT with the objective of ruling out coronary artery disease and identifying possible areas of myocardial ischemia. The resting electrocardiogram was unremarkable and stress test evaluation was made. The patient was admitted to the cardiac care unit and coronary artery bypass grafting was successfully performed. The presence of false negative nuclear stress test in the settings of positive electrocardiographic changes is a very unusual phenomenon and is usually secondary to balanced ischemia of the myocardial segments evaluated by SPECT-TL. Patients undergoing stress tests with these characteristics should undergo careful evaluation and a high level of suspicion should be adopted for further diagnostic assessment of coronary artery disease.

Cardiorespiratory fitness is positively correlated with cerebral white matter integrity in healthy seniors

High cardiorespiratory fitness (CRF) is an important protective factor reducing the risk of cardiac-related disability and mortality. Recent research suggests that high CRF also has protective effects on the brain's macrostructure and functional response. However, little is known about the potential relationship between CRF and the brain's white matter (WM) microstructure. This study explored the relationship between a comprehensive measure of CRF (VO(2) peak, total time on treadmill, and 1-minute heart rate recovery) and multiple diffusion tensor imaging measures of WM integrity. Participants were 26 healthy community dwelling seniors between the ages of 60 and 69 (mean=64.79 years, SD=2.8). Results indicated a positive correlation between comprehensive CRF and fractional anisotropy (FA) in a large portion of the corpus callosum. Both VO(2) peak and total time on treadmill contributed significantly to explaining the variance in mean FA in this region. The CRF-FA relationship observed in the corpus callosum was primarily characterized by a negative correlation between CRF and radial diffusivity in the absence of CRF correlations with either axial diffusivity or mean diffusivity. Tractography results demonstrated that portions of the corpus callosum associated with CRF primarily involved those interconnecting frontal regions associated with high-level motor planning. These results suggest that high CRF may attenuate age-related myelin declines in portions of the corpus callosum that interconnect homologous premotor cortex regions involved in motor planning.

Recent advances in the management of chronic stable angina I: approach to the patient, diagnosis, pathophysiology, risk stratification, and gender disparities

The potential importance of both prevention and personal responsibility in controlling heart disease, the leading cause of death in the USA and elsewhere, has attracted renewed attention. Coronary artery disease is preventable, using relatively simple and inexpensive lifestyle changes. The inexorable rise in the prevalence of obesity, diabetes, dyslipidemia, and hypertension, often in the risk cluster known as the metabolic syndrome, drives the ever-increasing incidence of heart disease. Population-wide improvements in personal health habits appear to be a fundamental, evidence based public health measure, yet numerous barriers prevent implementation. A common symptom in patients with coronary artery disease, classical angina refers to the typical chest pressure or discomfort that results when myocardial oxygen demand rises and coronary blood flow is reduced by fixed, atherosclerotic, obstructive lesions. Different forms of angina and diagnosis, with a short description of the significance of pain and silent ischemia, are discussed in this review. The well accepted concept of myocardial oxygen imbalance in the genesis of angina is presented with new data about clinical pathology of stable angina and acute coronary syndromes. The roles of stress electrocardiography and stress myocardial perfusion scintigraphic imaging are reviewed, along with the information these tests provide about risk and prognosis. Finally, the current status of gender disparities in heart disease is summarized. Enhanced risk stratification and identification of patients in whom procedures will meaningfully change management is an ongoing quest. Current guidelines emphasize efficient triage of patients with suspected coronary artery disease. Many experts believe the predictive value of current decision protocols for coronary artery disease still needs improvement in order to optimize outcomes, yet avoid unnecessary coronary angiograms and radiation exposure. Coronary angiography remains the gold standard in the diagnosis of coronary artery obstructive disease. Part II of this two part series will address anti-ischemic therapies, new agents, cardiovascular risk reduction, options to treat refractory angina, and revascularization.

Physical performance limitations among adult survivors of childhood brain tumors

BACKGROUND

Young adult survivors of childhood brain tumors (BTs) may have late effects that compromise physical performance and everyday task participation. The objective of this study was to evaluate muscle strength, fitness, physical performance, and task participation among adult survivors of childhood BTs.

METHODS

In-home evaluations and interviews were conducted for 156 participants (54% men). Results on measures of muscle strength, fitness, physical performance, and participation were compared between BT survivors and members of a population-based comparison group by using chi-square statistics and 2-sample t tests. Associations between late effects and physical performance and between physical performance and participation were evaluated in regression models.

RESULTS

: The median age of BT survivors was 22 years (range, 18-58 years) at the time of the current evaluation, and they had survived for a median of 14.7 years (range, 6.5-45.9 years) postdiagnosis. Survivors had lower estimates of grip strength (women, 24.7 + or - 9.2 kg vs 31.5 + or - 5.8 kg; men, 39.0 + or - 12.2 kg vs 53.0 + or - 10.1 kg), knee extension strength (women, 246.6 + or - 95.5 Newtons [N] vs 331.5 + or - 5.8 N; men, 304.7 + or - 116.4 N vs 466.6 + or - 92.1 N), and peak oxygen uptake (women, 25.1 + or - 8.8 mL/kg per minute vs 31.3 + or - 5.1 mL/kg per minute; men, 24.6 + or - 9.5 mL/kg per minute vs 33.2 + or - 3.4 mL/kg per minute) than members of the population-based comparison group. Physical performance was lower among survivors and was associated with not living independently (odds ratio [OR], 5.0; 95% confidence interval [CI], 2.0-12.2) and not attending college (OR, 2.3; 95% CI 1.2-4.4).

CONCLUSIONS

Muscle strength and fitness values among BT survivors were similar to those among individuals aged > or = 60 years and were associated with physical performance limitations. Physical performance limitations were associated with poor outcomes in home and school environments. The current data indicated an opportunity for interventions targeted at improving long-term physical function in this survivor population.

Physical activity and cardiovascular disease prevention in women: a review of the epidemiologic evidence

Epidemiologic studies suggest that as little as 30minutes of moderate-intensity physical activity per day can lower the risk of developing cardiovascular disease in women. Sedentary individuals who become physically active even at older ages derive cardiovascular benefits. Physical activity appears to slow the initiation and progression of CVD through salutary effects not only on adiposity but also on insulin sensitivity, glycemic control, incident type 2 diabetes, blood pressure, lipids, endothelial function, hemostasis, and inflammatory defense systems. Public health initiatives that promote moderate increases in physical activity may offer the best balance between efficacy and feasibility to improve cardiovascular health in sedentary populations.

Women and ischemic heart disease: evolving knowledge

Evolving knowledge regarding sex differences in coronary heart disease is emerging. Given the lower burden of obstructive coronary artery disease (CAD) and preserved systolic function in women, which contrasts with greater rates of myocardial ischemia and near-term mortality compared with men, we propose the term "ischemic heart disease" as appropriate for this discussion specific to women rather than CAD or coronary heart disease (CHD). This paradoxical difference, where women have lower rates of anatomical CAD but more symptoms, ischemia, and adverse outcomes, appears linked to abnormal coronary reactivity that includes microvascular dysfunction. Novel risk factors can improve the Framingham risk score, including inflammatory markers and reproductive hormones, as well as noninvasive imaging and functional capacity measurements. Risk for women with obstructive CAD is increased compared with men, yet women are less likely to receive guideline-indicated therapies. In the setting of non-ST-segment elevation acute myocardial infarction, interventional strategies are equally effective in biomarker-positive women and men, whereas conservative management is indicated for biomarker-negative women. For women with evidence of ischemia but no obstructive CAD, antianginal and anti-ischemic therapies can improve symptoms, endothelial function, and quality of life; however, trials evaluating impact on adverse outcomes are needed. We hypothesize that women experience more adverse outcomes compared with men because obstructive CAD remains the current focus of therapeutic strategies. Continued research is indicated to devise therapeutic regimens to improve symptom burden and reduce risk in women with ischemic heart disease.

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.

Incremental prognostic value of the exercise electrocardiogram in the initial assessment of patients with suspected angina: cohort study

OBJECTIVE

To determine whether resting and exercise electrocardiograms (ECGs) provide prognostic value that is incremental to that obtained from the clinical history in ambulatory patients with suspected angina attending chest pain clinics.

DESIGN

Multicentre cohort study.

SETTING

Rapid access chest pain clinics of six hospitals in England.

PARTICIPANTS

8176 consecutive patients with suspected angina and no previous diagnosis of coronary artery disease, all of whom had a resting ECG recorded. 4848 patients with a summary exercise ECG result recorded (positive, negative, equivocal for ischaemia) comprised the summary ECG subset of whom 1422 with more detailed exercise ECG data recorded comprised the detailed ECG subset.

MAIN OUTCOME MEASURE

Composite of death due to coronary heart disease or non-fatal acute coronary syndrome during median follow-up of 2.46 years.

RESULTS

Receiver operating characteristics curves for the basic clinical assessment model alone and with the results of resting ECGs were superimposed with little difference in the C statistic. With the exercise ECGs the C statistic in the summary ECG subset increased from 0.70 (95% confidence interval 0.68 to 0.73) to 0.74 (0.71 to 0.76) and in the detailed ECG subset from 0.74 (0.70 to 0.79) to 0.78 (0.74 to 0.82). However, risk stratified cumulative probabilities of the primary end point at one year and six years for all three prognostic indices (clinical assessment only; clinical assessment plus resting ECG; clinical assessment plus resting ECG plus exercise ECG) showed only small differences at all time points and at all levels of risk.

CONCLUSION

In ambulatory patients with suspected angina, basic clinical assessment encompasses nearly all the prognostic value of resting ECGs and most of the prognostic value of exercise ECGs. The limited incremental value of these widely applied tests emphasises the need for more effective methods of risk stratification in this group of patients.

A Re-examination of the Metabolic Equivalent Concept in Individuals With Coronary Heart Disease

OBJECTIVE

The metabolic equivalent (MET) is a commonly used method of quantifying the energy cost and intensity of physical activity. Recent studies have questioned the accuracy of the well-accepted value of a MET of 3.5 mL O2.kg(-1).min(-1). The goal of the present study was to compare the traditionally accepted value for 1 MET to direct measures of resting metabolic rate in a group of stable individuals with coronary heart disease (CHD).

METHODS

The primary cohort consisted of 109 (60 men and 49 women) subjects with documented coronary heart disease and a body mass index >or=25 kg/m2. Measurements included indirect calorimetry, body composition, and exercise capacity (peak oxygen uptake [VO2]). In a substudy of 17 (10 men, 7 women) normal weight subjects (body mass index <25 kg/m2), metabolic rate in the seated position was also measured.

RESULTS

Mean resting value for 1 MET was a VO2 value of 2.58 +/- 0.4 mL O2.kg(-1).min(-1) for overweight subjects measured in the supine position and 2.84 +/- 0.59 mL O2.kg(-1).min(-1) for normal weight individuals measured in the seated position. Caloric expenditure value was 0.74 +/- 0.12 kcal.kg(-1).h(-1) rather than the expected value of 1 kcal.kg(-1).h(-1). Values were similar between men and women. Women on beta-blockers had a lower resting metabolic rate (2.47 +/- 0.27 vs. 2.71 +/- 0.38 mL O2.kg(-1).min(-1)) (P < .05) than women not on beta-blocker therapy, whereas there was no effect of beta-blockers in men.

CONCLUSIONS

Findings confirm recent studies of otherwise healthy individuals and indicate that the average resting metabolic rate in subjects with coronary heart disease is 23% to 36% lower than the widely accepted value of 3.5 mL O2.kg(-1).min(-1). Results demonstrate the limitation of the convention of expressing energy expenditure in multiples of an assumed constant.

Gender-Specific Prediction of Cardiac Disease

Current guidelines recommend targeting the intensity of preventive cardiovascular interventions to the level of the patient's risk, which is usually obtained from a global risk score such as the Framingham equations. However, a large proportion of asymptomatic U.S. women (approximately 80-90%) are classified as low risk by the Framingham score, although they have a 1 in 2 chance of dying from cardiovascular disease (CVD) during their lifetime. A promising avenue for improving CVD risk stratification has come from recent studies evaluating the prognostic value of exercise testing in asymptomatic populations using test variables that are not related to exercise-induced ST-segment depression. In particular, it has been shown that 2 easily obtained noninvasive measures, low exercise capacity and slow heart rate recovery, have been linked to increased CVD and all-cause death in both women and men. These 2 simple yet powerful measures of risk that are readily available are useful tools for the practicing cardiologist who desires more accurate assessment of risk in a female patient, particularly if she is deemed as intermediate risk by the Framingham score. In addition, both exercise capacity and heart rate recovery are at least partially modifiable by regular physical activity. Exercise recommendations of at least 30 minutes of moderate physical activity most days of the week have been associated with 30% to 50% reductions in coronary events and coronary mortality and should be recommended to all patients regardless of their Framingham risk score.

Electrocardiographic exercise stress testing: an update beyond the ST segment

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