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

Screening for Coronary Artery Disease in Patients with Diabetes

PURPOSE OF REVIEW

The study aims to describe methods for detecting subclinical coronary artery disease (CAD) and their potential implications in asymptomatic patients with diabetes.

RECENT FINDINGS

Imaging tools can assess non-invasively the presence and severity of CAD, based on myocardial ischemia, coronary artery calcium score, and coronary computed tomography coronary angiography. Subclinical CAD is common in the general population ageing 50 to 64 years with any coronary atherosclerosis present in 42.1% and obstructive CAD in 5.2%. In patients with diabetes, an even higher prevalence has been noted. The presence of myocardial ischemia, obstructive CAD, and the extent of coronary atherosclerosis provide powerful risk stratification regarding the risk of cardiovascular events. However, randomized trials evaluating systematic screening in the general population or patients with diabetes have demonstrated only moderate impact on management and no significant impact on patient outcomes. Despite providing improved risk stratification, systematic screening of CAD is not recommended in patients with diabetes.

Identification of Silent Myocardial Ischemia in Patients with Long-Term Type 1 and Type 2 Diabetes

(1) Background: This study aimed to analyze epidemiological data to identify risk factors for silent myocardial ischemia in patients with long-term type 1 and type 2 diabetes. (2) Methods: An analysis was performed on 104 patients with long-term type 1 and type 2 diabetes who had not previously been diagnosed with cardiovascular disease. During hospitalization, patients were subjected to a standard ECG exercise test on a treadmill. If the test could not be performed or the result was uncertain, a pharmacological exercise test with dobutamine was performed. In the case of a positive exercise ECG test or a positive dobutamine test, the patient underwent coronary angiography. (3) Results: Atherosclerotic lesions were found in 24 patients. Patients with silent ischemia were significantly older and had a lower mean left ventricular ejection fraction and a higher incidence of carotid atherosclerosis. The presence of microvascular complications did not increase the risk of silent ischemia. (4) Conclusions: Silent heart ischemia is more common in type 2 than type 1 diabetes. Predisposing factors include older age, coexistence of carotid atherosclerosis, lower left ventricular ejection fraction, and smoking in patients with type 1 diabetes. Concomitant microvascular complications are not a risk factor.

French Society of Cardiology guidelines on exercise tests (part 2): Indications for exercise tests in cardiac diseases

The exercise test is performed routinely in cardiology; its main indication is the diagnosis of myocardial ischemia, evaluated along with the subject's pretest probability and cardiovascular risk level. Other criteria, such as analysis of repolarization, must be taken into consideration during the interpretation of an exercise test, to improve its predictive value. An exercise test is also indicated for many other cardiac diseases (e.g. rhythm and conduction disorders, severe asymptomatic aortic stenosis, hypertrophic cardiomyopathy, peripheral artery disease, hypertension). Moreover, an exercise test may be indicated for specific populations (women, the elderly, patients with diabetes mellitus, patients in a preoperative context, asymptomatic patients and patients with congenital heart defects). Some cardiac diseases (such as chronic heart failure or arterial pulmonary hypertension) require a cardiopulmonary exercise test. Finally, an exercise test or a cardiopulmonary exercise test is indicated to prescribe a cardiac rehabilitation programme, adapted to the patient.

Impact of Diabetes Mellitus on the Evaluation of Stable Chest Pain Patients: Insights From the PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain) Trial

Background

The impact of diabetes mellitus on the clinical presentation and noninvasive test (NIT) results among stable outpatients presenting with symptoms suggestive of coronary artery disease (CAD) has not been well described.

Methods and Results

The PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain) trial enrolled 10 003 patients with known diabetic status, of whom 8966 were tested as randomized and had interpretable NIT results (1908 with diabetes mellitus, 21%). Differences in symptoms and NIT results were evaluated using logistic regression. Patients with diabetes mellitus (versus without) were similar in age (median 61 versus 60 years) and sex (female 54% versus 52%), had a greater burden of cardiovascular comorbidities, and had a similar likelihood of nonchest pain symptoms (29% versus 27%). The Diamond‐Forrester/Coronary Artery Surgery Study score predicted that patients with diabetes mellitus (versus without) had similar likelihood of obstructive CAD (low 1.8% versus 2.7%; intermediate 92.3% versus 92.6%; high 5.9% versus 4.7%). Physicians estimated patients with diabetes mellitus to have a higher likelihood of obstructive CAD (low to very low: 28.3% versus 40.1%; intermediate 63.9% versus 55.9%; high to very high 7.8% versus 4.0%). Patients with diabetes mellitus (versus without) were more likely to have a positive NIT result (15% versus 11%; adjusted odds ratio, 1.23; P=0.01).

Conclusions

Stable chest pain patients with and without diabetes mellitus have similar presentation and pretest likelihood of obstructive CAD; however, physicians perceive that patients with diabetes mellitus have a higher pretest likelihood of obstructive CAD, an assessment supported by increased risk of a positive NIT. Further evaluation of diabetes mellitus's influence on CAD assessment is required.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01174550.

Value of Exercise ECG for Risk Stratification in Suspected or Known CAD in the Era of Advanced Imaging Technologies

Exercise stress electrocardiography (ExECG) is underutilized as the initial test modality in patients with interpretable electrocardiograms who are able to exercise. Although stress myocardial imaging techniques provide valuable diagnostic and prognostic information, variables derived from ExECG can yield substantial data for risk stratification, either supplementary to imaging variables or without concurrent imaging. In addition to exercise-induced ischemic ST-segment depression, such markers as ST-segment elevation in lead aVR, abnormal heart rate recovery post-exercise, failure to achieve target heart rate, and poor exercise capacity improve risk stratification of ExECG. For example, patients achieving ≥10 metabolic equivalents on ExECG have a very low prevalence of inducible ischemia and an excellent prognosis. In contrast, cardiac imaging techniques add diagnostic and prognostic value in higher-risk populations (e.g., poor functional capacity, diabetes, or chronic kidney disease). Optimal test selection for symptomatic patients with suspected coronary artery disease requires a patient-centered approach factoring in the risk/benefit ratio and cost-effectiveness.

Subclinical cardiovascular disease in type 2 diabetes mellitus: To screen or not to screen

The prevalence of type 2 diabetes mellitus (T2DM) has risen in recent decades, and cardiovascular disease remains the leading cause of death in this population. Several clinical trials have demonstrated the benefit of tight control of risk factors on the incidence and mortality of cardiovascular disease. However, in clinical practice, few patients achieve the therapeutic goals. The current diagnostic procedures for subclinical cardiovascular disease in T2DM patients have not been shown to improve prognosis or mortality, probably because they do not categorize cardiovascular risk. Thus, clinical practice guidelines do not systematically recommend screening for subclinical atherosclerosis in these patients, although it is known that patients with extra-coronary atherosclerosis, microangiopathy and poorly-controlled cardiovascular risk factors are at high risk for cardiovascular disease. Improvements in the reliability of diagnostic tests, with fewer side effects and better cost efficiency, may better help to stratify cardiovascular risk in this group of patients, and further evaluation on this topic should be considered.

Interleukin-6 and activin A are independently associated with cardiovascular events and mortality in type 2 diabetes: the prospective Asker and Bærum Cardiovascular Diabetes (ABCD) cohort study

Background

Novel and robust cardiovascular (CV) markers are needed to improve CV morbidity and mortality risk prediction in type 2 diabetes (T2D). We assessed the long term predictive value of 4 novel CV risk markers for major CV events and mortality.

Methods

We included patients with T2D who had cytokines (interleukin [IL]-6 and activin A [actA]), a maximum stress ECG test (evaluated by the normalization pattern in early recovery phase) and echocardiography (evaluated by a measure of the left ventricular filling pressure - E/Em) assessed at baseline. The primary endpoint was time to first of any of the following events: myocardial infarction, stroke, hospitalization for unstable angina pectoris and death. All outcomes were adjudicated by independent experts. We used Cox proportional hazard modeling, Harrell C-statistic and the net reclassification improvement (NRI) to assess the additional value beyond conventional markers (age, gender, prior CV disease, HDL, creatinine, diastolic BP, microalbuminuria).

Results

At baseline the study cohort (n = 135, mean age/diabetes duration/HbA1c: 59 yrs/7 yrs/7.6% [59 mmol/mol], 26% females) had moderate elevated CV risk (42% microalbuminuria, mean Framingham 10 year CV-risk 9.6%). During 8.6 yrs/1153.7 person years, 26 patients experienced 36 events. All 4 novel risk markers were significantly associated with increased risk of the primary endpoint, however, only IL-6 and actA improved C-statistic and NRI (+0.119/43.2%, +0.065/20.3% respectively) compared with the conventional CV risk factors.

Conclusions

IL-6 and actA may provide prognostic information on CV events and mortality in T2D beyond conventional CV risk factors.

Trial registration

ClinicalTrials.gov: NCT00133718

Diagnosis of coronary artery disease in persons with diabetes mellitus

Coronary heart disease (CHD) is the leading cause of morbidity and mortality in patients with diabetes. Asymptomatic CHD in these patients is elusive and carries a poor prognosis given the fact that an unheralded acute myocardial infarction or sudden cardiac death frequently constitutes its first presentation. Because effective screening for asymptomatic patients with type 2 diabetes for both the presence and severity of CHD is intuitively appealing, we have summarized the utility and prognostic value of various diagnostic modalities (both functionally and anatomically) in enhancing risk stratification and leading to improved and more aggressive management of the risk factors. There exist some evidence and recommendations for screening of asymptomatic persons with diabetes using certain modalities. More research is needed to define potential subsets of patients with diabetes who may benefit from additional testing for asymptomatic CHD.

Myocardial perfusion scintigraphy in asymptomatic diabetic patients: a critical review

The increasing prevalence of diabetes mellitus and the associated high cardiovascular risk has made the non-invasive identification of silent coronary heart disease in diabetic individuals an important issue. This strategy could identify higher risk asymptomatic patients with diabetes mellitus in whom coronary revascularization may improve the outcome beyond that achieved by currently recommended medical management. Stress myocardial perfusion imaging has been shown to be effective in detecting coronary heart disease and predicting adverse cardiac events in asymptomatic diabetic patients. However, the clinical utility of myocardial perfusion scintigraphy is debated intensively due to the paucity of prospective and outcome based evidence. The controversy stems from several observational studies, epidemiologic data and cost-effectiveness analyses. Thus, although several authors and professional organizations advocate the use of stress imaging for screening higher risk asymptomatic diabetic patients, others are cautious in recommending any kind of stress testing in that population. This review is based on a broad survey of the literature and discusses the potential role of stress myocardial perfusion scintigraphy in screening asymptomatic diabetic subjects for coronary heart disease in the current era and in relation with other non-invasive screening tools.

Maximal exercise electrocardiography responses and coronary heart disease mortality among men with diabetes mellitus

BACKGROUND

An abnormal ECG during maximal exercise testing has been shown to be a powerful predictor of future coronary heart disease (CHD) mortality in asymptomatic men. However, little is known about the relationship between exercise ECG responses and CHD risk in men with diabetes mellitus.

METHODS AND RESULTS

We examined the association between exercise ECG responses and mortality in 2854 men with documented diabetes mellitus (mean age 49.5 years) who completed a maximal treadmill exercise test during the period from 1974 to 2001 and who were without a previous cardiovascular disease (CVD) event at baseline. Mortality due to all causes, CHD, and CVD were the main outcome measures across categories of exercise ECG responses, with stratification by cardiorespiratory fitness, quantified as treadmill test duration. During an average follow-up of 16 years, 441 deaths (210 CVD and 133 CHD) were identified. Across normal, equivocal, and abnormal exercise ECG groups, age- and examination year-adjusted CHD mortality rates per 10 000 person-years were 23.0, 48.6, and 69.0, respectively (P(trend)<0.001). After further adjustment for fasting plasma glucose level, smoking, body mass index, hypercholesterolemia, hypertension, family history of CVD or diabetes mellitus, abnormal resting ECG responses, and cardiorespiratory fitness, hazard ratios (95% confidence intervals) were 1.00 (referent), 1.68 (1.01 to 2.77), and 2.21 (1.41 to 3.46; P(trend)<0.001). Similar patterns of associations were noted between exercise ECG testing and both CVD and all-cause mortality risk.

CONCLUSIONS

Among men with diabetes mellitus, equivocal and abnormal exercise ECG responses were associated with higher risk of all-cause, CVD, and CHD mortality.

Heart rate adjustments and analysis of recovery patterns of ST-segment depression in type 2 diabetes

AIMS

To investigate the diagnostic value for coronary artery disease (CAD) detection of evaluating time- and heart rate (HR)-related ST-segment changes (the ST/HR-slope) and the post-exercise recovery pattern (the ST/HR-recovery loop) in patients with type 2 diabetes mellitus (T2DM).

METHODS AND RESULTS

Ninety-one patients (22 female, age 59+/-9 years) with T2DM (diabetes duration 6+/-6 years) performed an exercise ECG-test that was evaluated using the ST/HR slope (cut-off</=-2.4 microV/bpm) and -recovery loop patterns (abnormal versus normal) and compared to the conventional >/=1 mm ST-segment depression criterion and dobutamine stress echo-cardiography, all evaluated against coronary angiography irrespective of stress test results. Coronary angiography revealed CAD in 20 men and 3 women (25%). Sensitivity for the conventional exercise test and stress echocardiography was low (0.35 and 0.30), but increased significantly using the ST/HR-slope (0.45), the recovery loop (0.86) or the combined ST/HR slope and recovery loop criterion (0.91). The associations between angiographic CAD-detection and the different tests expressed by the Odds ratio demonstrated an added value of performing ST/HR analysis both over pre-test CAD risk profile and the established techniques.

CONCLUSION

T2DM patients capable of performing an exercise test could be assessed with the ST/HR-analysis for selecting patients to angiography. However, further studies including a higher number of patients are needed to confirm the diagnostic value of this approach.

Chest pain: an update

PURPOSE OF REVIEW

Chest pain is one of the most common symptoms for seeking acute medical care. Evidence of myocardial ischemia, however, can only be established in a minority of patients. The establishment or ruling out of myocardial ischemia is difficult and the cost is high. An effective rationale for ischemia detection, without unnecessary hospital admission, is needed. The development of chest pain units potentially offers a rapid, effective way of identifying patients at high risk for acute coronary syndromes, as well as those with a low probability of ischemia. Other cardiac or noncardiac causes of chest pain should also be considered.

RECENT FINDINGS

Recent developments in chest pain, including the ruling in or out of ischemic pain by triage and different ischemia detection methods, are discussed. Other causes of chest pain such as esophageal, drug related, psychiatric and post-coronary bypass surgery pain are also discussed. Recent findings on syndrome X are reviewed and patients with myocardial infarction presenting without chest pain are discussed.

SUMMARY

The possibility of safely and quickly ruling out myocardial ischemia by point-of-care biochemical analyses is reviewed, which might influence our clinical handling of chest pain patients. The importance of biopsychosocial factors, pain perception, esophageal dysfunction, drugs and the coronary artery bypass procedure in itself, is discussed and vital clinical information is provided for the handling of our chest pain patients.

Silent myocardial ischemia is associated with autonomic neuropathy and other cardiovascular risk factors in type 1 and type 2 diabetic subjects, especially in those with microalbuminuria

The prevalence of silent myocardial ischemia (SMI) seems to be above average in diabetic subjects. As routine screening is costly, identifying high-risk populations is mandatory. This study aimed to estimate the prevalence of SMI in diabetic subjects and in controls and to define the diabetic population at risk. We studied 353 asymptomatic caucasian subjects (217 with diabetes and 136 controls matched by age, sex, and cardiovascular risk factors) with normal resting ECG. The diabetic group included 39 type 1 and 178 type 2 diabetics (age 57 +/- 11 yr, 162 males/55 females). Subjects performed the Treadmill Test (TT) and, when abnormal, underwent single-photon emission computed tomography (SPECT) with exercise testing or dipyridamole injection. Coronary angiography was performed if the SPECT was suggestive of ischemia. TT was positive in 16 (8.5%) diabetics: 3 with type 1 and 13 with type 2. No controls had positive TT. SPECT was performed in 13 subjects and was positive in 10; angiography was performed in 7 and identified significant lesions in all cases. Patients with SMI were older and had a higher prevalence of autonomic neuropathy, hypertension, and dyslipidemia than those without. Microalbuminuria was also higher in the SMI group (613 +/- 211 vs 72 +/- 245 mg/d; p < 0.05). We conclude that diabetic patients aged over 60 with autonomic neuropathy and other cardiovascular risk factors should be screened for the presence of SMI especially if they have increased microalbuminuria.

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

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

Diagnosing coronary artery disease in diabetic patients

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

Better decisions through science: exercise testing scores

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