Stress testing in cardiac evaluation : current concepts with emphasis on the ECG

Relationship between pre-procedural non-ischemic ST-segment depression and the clinical outcomes after catheter ablation in persistent atrial fibrillation patients

BACKGROUND

ST-segment depression suggests the presence of coronary artery disease (CAD) during sinus rhythm, but the clinical significance, including the outcomes after catheter ablation (CA), in atrial fibrillation (AF) patients remain unknown.

METHODS

The present study included persistent AF (PerAF) patients from the Osaka Rosai Atrial Fibrillation ablation (ORAF) registry who underwent an initial ablation and had no history of CAD. We assigned the patients based on the presence of ST-segment depression before CA and evaluated the impact of relevant factors on ST-segment depression and the relationship between ST-segment depression, including leads locations (anterior leads, inferior leads, and lateral leads) or depression type (upsloping, horizontal, and downsloping) or the degree of ST-segment depression and late recurrence of AF (LRAF).

RESULTS

This study population included a total of 551 patients of whom 189 had ST-segment depression. The median follow-up duration was 397 days and LRAF occurred in 195 patients. By multiple regression analysis, diabetes mellitus, hemoglobin, brain natriuretic peptide, left ventricular ejection fraction, and left atrial diameter were significant determinants of ST-segment depression before CA. Kaplan-Meier analysis demonstrated that the patients with ST-segment depression had a significantly greater risk of LRAF than those without (p < 0.001). Multivariate Cox proportional hazards analysis showed ST-segment depression was independently and significantly associated with a higher risk of LRAF (p < 0.001). The patients with ST-segment depression ≥0.15 mV had a significantly higher risk of LRAF than those with ST-segment depression ≥0.15 mV (p < 0.001). No significant differences among the ST-segment depression lead locations and ST-segment depression type were observed.

CONCLUSION

Non-ischemic ST-segment depression during AF rhythm was significantly associated with LRAF post CA in PerAF patients.

Consensus document on chronic coronary syndrome assessment and risk stratification in Portugal: A position paper statement from the [Portuguese Society of Cardiology's] Working Groups on Nuclear Cardiology, Magnetic Resonance and Cardiac Computed Tomography, Echocardiography, and Exercise Physiology and Cardiac Rehabilitation

Despite constant medical evolution, the reimbursement policy of Portuguese National Health Service (NHS) for the study and risk stratification of coronary heart disease has remained unchanged for several decades. Lack of adjustment to contemporary clinical practice has long been evident. However, the recent publication of the European Guidelines for diagnosis and treatment of chronic coronary syndromes further highlighted this gap and the urgent need for a change. Prompted by these Guidelines, the Working Group on Nuclear Cardiology, Cardiac Magnetic Resonance and Cardiac CT, the Working Group on Echocardiography and the Working Group on Stress Pathophysiology and Cardiac Rehabilitation of the Portuguese Society of Cardiology, began a process of joint reflection on the current limitations and how these recommendations could be applied in Portugal. To this end, the authors suggest that the new imaging methods (stress echocardiogram, cardiac computed tomography and cardiac magnetic resonance), should be added to exercise treadmill stress test and myocardial perfusion scintigraphy in the available exam portfolio within the Portuguese NHS. This change would allow full adoption of European guidelines and a better use of tests, according to clinical context, availability and local specificities. The adoption of clinical guidance standards, based on these assumptions, would translate into a qualitative improvement in the management of these patients and would promote an effective use of the available resources, with potential health and financial gains.

Long-Term Outcomes in Patients Undergoing Percutaneous Coronary Intervention with or without Preprocedural Exercise Stress Test

BACKGROUND

Although current guidelines recommend noninvasive stress tests prior to elective percutaneous coronary intervention (PCI), it is unknown whether antecedent exercise stress test (EST) affects the outcomes of patients undergoing PCI for stable ischemic heart disease (SIHD). This study aimed to investigate long-term outcomes in patients undergoing elective PCI with or without EST.

METHODS

We studied 2,674 patients undergoing elective PCI using drug-eluting stents for SIHD. Patients were divided into the 2 groups: the test group underwent EST with a positive result within 180 days prior to PCI (n = 668), whereas the non-test group did not undergo any noninvasive stress tests (n = 2,006). The primary outcome was all-cause death or myocardial infarction (MI).

RESULTS

Over 5 years after the index PCI, the risk of all-cause death or MI was significantly lower in the test group than in the non-test group in overall population (3.3% vs. 10.9%; adjusted hazard ratio [HR], 0.34; 95% confidence interval [CI], 0.22-0.55; P < 0.001), and in propensity score-matched population (668 pairs) (3.3% vs. 6.3%; adjusted HR, 0.52; 95% CI, 0.30-0.89; P = 0.018). However, the incidence of any revascularization was similar between the 2 groups in overall (16.7% vs. 16.8%; adjusted HR, 0.99; 95% CI, 0.79-1.25; P = 0.962) and matched population (16.7% vs. 18.3%; adjusted HR, 0.91; 95% CI, 0.70-1.19; P = 0.509).

CONCLUSION

Patients who underwent elective PCI with EST had a reduced risk of all-cause death or MI than those undergoing PCI without stress tests.

Transdermal Optical Imaging Reveal Basal Stress via Heart Rate Variability Analysis: A Novel Methodology Comparable to Electrocardiography

The present study examined the validity of a novel physiological measurement technology called transdermal optical imaging (TOI) technology at assessing basal stress. This technology conveniently, contactlessly, and remotely measures facial blood flow changes using a conventional digital video camera. We compared data from TOI against the pulse data collected from the FDA approved BIOPAC system. One hundred thirty-six healthy adults participated in the study. We found that TOI measurements of heart rate and heart rate variability (HRV), which reflects basal stress, corresponded strongly to those obtained from BIOPAC. These findings indicate that TOI technology is a viable method to monitor heart rate and HRV not only accurately but also conveniently, contactlessly, and remotely. Further, measures of HRV obtained via TOI serves as a valid index of basal stress. Potential applications of this technology in psychological research and other fields are discussed.

Comparison between parameters from maximal cycle ergometer test first without respiratory gas analysis and thereafter with respiratory gas analysis among healthy prepubertal children

It is important to distinguish true and clinically relevant changes and methodological noise from measure to measure. In the clinical practice, maximal cycle ergometer tests are typically performed first without respiratory gas analysis and thereafter, if needed, with respiratory gas analysis. Therefore, we report a comparison of parameters from maximal cycle ergometer exercise tests that were done first without respiratory gas analysis and thereafter with it in 38 prepubertal and healthy children (20 girls, 18 boys). The Bland-Altman method was used to assess agreement in maximal workload (WMAX), heart rate (HR), and systolic blood pressure (SBP) between rest and maximum. Girls achieved higher WMAX in the exercise tests with respiratory gas analysis compared with exercise tests without respiratory gas analysis (p = 0.016), whereas WMAX was similar in the tests among boys. Maximal HR (proportional offset, -1%; coefficients of variation, 3.3%) and highest SBP (proportional offset, 3%; coefficients of variation, 10.6%) were similar in the tests among children. Precision and agreement for HR improved and precision for SBP worsened with increasing exercise intensity. Heteroscedasticity was not observed for WMAX, HR, or SBP. We conclude that maximal cycle ergometer tests without and with respiratory gas analysis can be used consecutively because measurement of respiratory gases did not impair performance or have a significant effect on the maximality of the exercise tests. Our results suggest that similar references can be used for children who accept or refuse using a mask during a maximal exercise test.

Does coronary Atherosclerosis Deserve to be Diagnosed earlY in Diabetic patients? The DADDY-D trial. Screening diabetic patients for unknown coronary disease

OBJECTIVES

To evaluate if screening and treatment of asymptomatic coronary artery disease (CAD) are effective in preventing first cardiac event in diabetics.

METHODS

Diabetic patients without known CAD were randomly assigned to undergo a screening for silent myocardial ischemia followed by revascularization or to continue follow-up. The reduction of cardiac death (CD) or nonfatal myocardial infarction (MI) represented the primary aim; secondary aim was the prevention of heart failure (HF).

RESULTS

From September 2007 to May 2012, 520 patients (62 years; 104 female) were enrolled. Silent CAD was found in 20 of 262 patients (7.6%), revascularization was performed in 12 (4.6%). After a mean follow-up of 3.6 years 12 events (4.6%) occurred in the study group and 14 (5.4%) in the follow-up (HR=0.849, 95% CI: 0.393-1.827, P=0.678). The occurrence of first HF episode did not differ between groups: 2 (0.8%) in screened and 7 (2.7%) in follow-up (HR=0.273, 95% CI: 0.057-1.314, P=0.083). Subgroup analysis revealed a significantly lower HF episodes among patients with intermediate cardiovascular risk (Log rank P=0.022). Additionally, when CD and MI were analysed within subgroups, a significant lower number of CDs was observed among older than 60 years (P=0.044).

CONCLUSION

Screening and revascularization of silent CAD in diabetics, failed to demonstrate a significant reduction in cardiac events and HF episodes. However, our data indicate that further research is warranted in patients older than 60 years and those with an intermediate cardiovascular risk. CLINICALTRIALS.GOV: NCT00547872.

EXERCISE TESTS IN CARDIOLOGY: PAST, PRESENT AND FUTURE (PART I)

The literary review is focused on diagnostics of coronary heart disease (CHD) with the use of the most common functional exercise tests. The benefits and the lacks are discussed of a variety of tests for suspected CHD. The results of longitude controlled trials make now the physicians able to precisely enough estimate a risk of complications in a patient. Several diagnostic indexes are observed, that are based on complex analysis of clinical and simple instrumental parameters for long term risk evaluation in CHD and for the selection of adequate treatment method.

Does knowledge of the cost of cardiovascular tests influence physician ordering patterns?

INTRODUCTION

The United States spends a higher percentage of its gross domestic product on health care than any other country. Previous efforts to curtail health care spending have had minimal impact. We hypothesized that informing physicians of the cost of expensive cardiovascular diagnostic tests would change their ordering behavior.

MATERIALS AND METHODS

Hospitalist physicians (n = 38) were randomly assigned to either seeing or not seeing the cost of diagnostic tests, via a computer pop-up screen, at the time of order entry. Patients were inpatients on a general medical service. Cost-aware physicians were shown the cost of the test they ordered as well as the cost of similar tests with different costs. There was a 4-month baseline period prior to randomization followed by a 4-month intervention period. The primary outcome measure was a change in the proportion of imaging stress tests in the study period.

RESULTS

Of the total number of stress tests ordered (imaging and nonimaging), cost-aware physicians ordered 89% of their tests with imaging during both the baseline and study periods. Cost-unaware physicians ordered 91% imaging tests during the baseline period and 87% during the study period. There were no significant differences between the groups regarding change in ordering from baseline to study period. Both groups showed a slight increase (P < 0.03) in ordering the more expensive regadenoson nuclear stress tests (cost-aware: 30% baseline, 44% study period; cost-unaware: 36% baseline, 41% study period).

DISCUSSION

Informing physicians of the cost of certain diagnostic tests is not a sufficient intervention to influence their ordering behavior.

Enhancing of women functional status with metabolic syndrome by cardioprotective and anti-inflammatory effects of combined aerobic and resistance training

These data describe the effects of combined aerobic plus resistance training (CT) with regards to risk factors of metabolic syndrome (MetS), quality of life, functional capacity, and pro- and anti-inflammatory cytokines in women with MetS. In this context, thirteen women (35.4 ± 6.2 yr) completed 10 weeks of CT consisting of three weekly sessions of ~60 min aerobic training (treadmill at 65-70% of reserve heart rate, 30 min) and resistance training (3 sets of 8-12 repetitions maximum for main muscle groups). Dependent variables were maximum chest press strength; isometric hand-grip strength; 30 s chair stand test; six minute walk test; body mass; body mass index; body adiposity index; waist circumference; systolic (SBP), diastolic and mean blood pressure (MBP); blood glucose; HDL-C; triglycerides; interleukins (IL) 6, 10 and 12, osteoprotegerin (OPG) and serum nitric oxide metabolite (NOx); quality of life (SF-36) and Z-Score of MetS. There was an improvement in muscle strength on chest press (p = 0.009), isometric hand-grip strength (p = 0.03) and 30 s chair stand (p = 0.007). There was a decrease in SBP (p = 0.049), MBP (p = 0.041), Z-Score of MetS (p = 0.046), OPG (0.42 ± 0.26 to 0.38 ± 0.19 ng/mL, p<0.05) and NOx (13.3 ± 2.3 µmol/L to 9.1 ± 2.3 µmol/L; p<0.0005). IL-10 displayed an increase (13.6 ± 7.5 to 17.2 ± 12.3 pg/mL, p < 0.05) after 10 weeks of training. Combined training also increased the perception of physical capacity (p = 0.011). This study endorses CT as an efficient tool to improve blood pressure, functional capacity, quality of life and reduce blood markers of inflammation, which has a clinical relevance in the prevention and treatment of MetS.

Comparison of treadmill exercise stress cardiac MRI to stress echocardiography in healthy volunteers for adequacy of left ventricular endocardial wall visualization: A pilot study

PURPOSE

To compare exercise stress cardiac magnetic resonance (cardiac MR) to echocardiography in healthy volunteers with respect to adequacy of endocardial visualization and confidence of stress study interpretation.

MATERIALS AND METHODS

Twenty-eight healthy volunteers (age 28 ± 11 years, 15 males) underwent exercise stress echo and cardiac MR one week apart assigned randomly to one test first. Stress cardiac MR was performed using an MRI-compatible treadmill; stress echo was performed as per routine protocol. Cardiac MR and echo images were independently reviewed and scored for adequacy of endocardial visualization and confidence in interpretation of the stress study.

RESULTS

Heart rate at the time of imaging was similar between the studies. Average time from cessation of exercise to start of imaging (21 vs. 31 s, P < 0.001) and time to acquire stress images (20 vs. 51 s, P < 0.001) was shorter for cardiac MR. The number of myocardial segments adequately visualized was significantly higher by cardiac MR at rest (99.8% vs. 96.4%, P = 0.002) and stress (99.8% vs. 94.1%, P = 0.001). The proportion of subjects in whom there was high confidence in the interpretation was higher for cardiac MR than echo (96% vs. 60%, P = 0.005).

CONCLUSION

Exercise stress cardiac MR to assess peak exercise wall motion is feasible and can be performed at least as rapidly as stress echo.

The prognostic value of normal stress cardiac magnetic resonance in patients with known or suspected coronary artery disease: a meta-analysis

BACKGROUND

Ischemia detection with stress cardiac magnetic resonance (CMR) is typically based on induction of either myocardial perfusion defect or wall motion abnormality. Single-center studies have shown the high value of stress CMR for risk stratification. The aim of this study was to define the prognostic value of stress CMR for prediction of adverse cardiac events in patients with known or suspected coronary artery disease.

METHODS AND RESULTS

Studies published between January 1985 and April 2012 were identified by database search. We included studies using stress CMR to evaluate subjects with known or suspected coronary artery disease and providing primary data on clinical outcomes of nonfatal myocardial infarction or cardiac death with a follow-up time ≥3 months. Total of 14 studies were finally included, recruiting 12 178 patients. The negative predictive value for nonfatal myocardial infarction and cardiac death of normal CMR was 98.12% (95% confidence interval, 97.26-98.83) during a weighted mean follow-up of 25.3 months, resulting in estimated event rate after a negative test equal to 1.88% (95% confidence interval, 1.17-2.74). The corresponding annualized event rate after a negative test was 1.03%. Comparable negative predictive values for major coronary events were obtained in studies considering the absence of inducible perfusion defect compared with those evaluating the absence of inducible wall motion abnormality (98.39% versus 97.31%, respectively; P=0.227 by meta-regression analysis).

CONCLUSIONS

Stress CMR has a high negative predictive value for adverse cardiac events, and the absence of inducible perfusion defect or wall motion abnormality shows a similar ability to identify low-risk patients with known or suspected coronary artery disease.

Effects of eight weeks of resistance training on the risk factors of metabolic syndrome in overweight /obese women - "A Pilot Study"

BACKGROUND

The purpose of the present study was to examine the effects of eight weeks of resistance training (RT) on anthropometric, cardiovascular and biochemical risk factors of metabolic syndrome (MetS), and neuromuscular variables on overweight/obese women.

METHODS

Fourteen middle-aged (33.9 ± 8.6 years) overweight/obese women (body mass index - BMI 29.6 ± 4.1 kg/m2) underwent 24 sessions (3 times/week) of a whole body RT program with 3 sets of 8-12 repetitions maximum (RM). The following variables were evaluated: maximum strength on chest press and frontal lat pull-down; isometric hand-grip strength; biceps brachii (BB) and rectus femoris (RF) muscle thickness, body mass; BMI; body adiposity index (BAI); waist, hip and neck circumferences; visceral fat volume; blood glucose; glycated hemoglobin (HbA1c); insulin; HDL-C and triglycerides.

RESULTS

There was an increase of chest press (from 52.9 ± 9.7 to 59.8 ± 7.7 kg; P = 0.02) and front lat pull-down (from 51.5 ± 7.5 to 57.6 ± 9.2 kg; P = 0.01) muscle strength, isometric handgrip (P = 0.02) and RF muscle thickness (from 42.2 ± 8.5 to 45.1 ± 7.3 mm; P = 0.02) after the 8 week RT program. There were no statistically significant alterations on plasma glucose, HbA1c, insulin, triglycerides, HDL-C, anthropometric indexes and BB muscle thickness (p > 0.05).

CONCLUSIONS

A RT program without caloric restriction promotes an increase on muscle thickness and strength, with no effects on risk factors of MetS in overweight/obese women.

Value of exercise tolerance testing in evaluation of diabetic patients presented with atypical chest discomfort

BACKGROUND

Coronary artery disease is the single most important cause of mortality and morbidity in diabetic patients. Electrocardiographic stress test is a non-invasive modality to screen significant coronary involvement in minimally symptomatic diabetics.

OBJECTIVES

We investigated the Positive Predictive Value (PPV) of this test in comparison with coronary angiography.

MATERIALS AND METHODS

130 diabetic patients with atypical chest discomfort were studied and tested using Exercise Tolerance Test (ETT) among which 100 cases showed positive results that further were studied invasively by selective coronary angiography.

RESULTS

The positive predictive value of ETT for diagnosis of Coronary Artery Disease (CAD)among diabetic patients presented with atypical chest discomfort was 77%.

CONCLUSION

We conclude that electrocardiographic stress test is a valuable inexpensive non-invasive screening test in diabetic patients with atypical chest discomfort.

Selected physiological effects of ultrafine particles in acute cardiovascular morbidity

Ultrafine particles (UFPs) have emerged as a potentially important environmental health concern as they are produced in large numbers by vehicle emissions and may contribute to previously reported associations between traffic pollution and acute cardiovascular morbidity. This review examines recent epidemiological evidence of UFP exposures and selected physiological outcomes that may be modified as part of the underlying causal pathway(s) linking particulate air pollution and acute cardiovascular morbidity. Outcomes examined included changes in heart rate variability (HRV) (autonomic function), ST-segment depression (myocardial ischemia), QT-interval (ventricular repolarization), and endothelial vasomotor function. Twenty-two studies were reviewed in total: 10 prospective panel studies and 12 randomized cross-over studies. Sixteen studies identified a significant relationship between UFPs and at least one of the above outcomes and current evidence generally supports the biological plausibility of a relationship between UFPs and acute cardiovascular morbidity. However, discrepancies were apparent in the direction of observed associations, particularly for HRV and ventricular repolarization. Reasons for these discrepancies may include differences in particle composition, time-point of clinical evaluation, and population susceptibilities. Nevertheless, evidence to date suggests that UFPs have a measureable impact on physiological measures known to be altered in cases of acute cardiovascular morbidity. Moving forward, expanded use of personal exposure measures is recommended for prospective panel studies to minimize exposure misclassification. In addition, effort should be made to include more women in studies of the acute cardiovascular effects of UFPs as findings to date generally reflect responses in men.

MR-compatible treadmill for exercise stress cardiac magnetic resonance imaging

This article describes an MR-safe treadmill that enables cardiovascular exercise stress testing adjacent to the MRI system, facilitating cardiac MR imaging immediately following exercise stress. The treadmill was constructed of nonferromagnetic components utilizing a hydraulic power system. Computer control ensured precise execution of the standard Bruce treadmill protocol commonly used for cardiovascular exercise stress testing. The treadmill demonstrated no evidence of ferromagnetic attraction and did not affect image quality. Treadmill performance met design specifications both inside and outside the MRI environment. Ten healthy volunteers performed the Bruce protocol with the treadmill positioned adjacent to the MRI table. Upon reaching peak stress (98 ± 8% of age-predicted maximum heart rate), the subjects lay down directly on the MRI table, a cardiac array coil was placed, an intravenous line connected, and stress cine and perfusion imaging performed. Cine imaging commenced on average within 24 ± 4 s and was completed within 40 ± 7 s of the end of exercise. Subject heart rates were 86 ± 9% of age-predicted maximum heart rate at the start of imaging and 81 ± 9% of age-predicted maximum heart rate upon completion of cine imaging. The MRI-compatible treadmill was shown to operate safely and effectively in the MRI environment.

Magnetic field threshold for accurate electrocardiography in the MRI environment

Although the electrocardiogram is known to be nondiagnostic within the bore of any high-field magnet due to the magnetohydrodynamic effect, there are an increasing number of applications that require accurate electrocardiogram monitoring of a patient inside the MRI room but outside of the magnet bore. Magnetohydrodynamic effects on the ST segment of the electrocardiogram waveform were investigated in six subjects at magnetic field strengths ranging from 6.4 mT to 652 mT at the aortic midarch, and the electrocardiogram was found to be accurate at magnetic fields below 70 mT. This corresponds to a distance of 160 cm from the isocenter and 80 cm from the bore entrance for the 1.5-T MRI system used in this study. These results can be translated to any MRI system, with knowledge of the fringe field. Accurate electrocardiogram monitoring is feasible in close proximity to the MRI magnet, such as during and after pharmacologic or exercise stress, or interventional or surgical procedures performed in the MRI room.

Real-time cine and myocardial perfusion with treadmill exercise stress cardiovascular magnetic resonance in patients referred for stress SPECT

BACKGROUND

To date, stress cardiovascular magnetic resonance (CMR) has relied on pharmacologic agents, and therefore lacked the physiologic information available only with exercise stress.

METHODS

43 patients age 25 to 81 years underwent a treadmill stress test incorporating both Tc99m SPECT and CMR. After rest Tc99m SPECT imaging, patients underwent resting cine CMR. Patients then underwent in-room exercise stress using a partially modified treadmill. 12-lead ECG monitoring was performed throughout. At peak stress, Tc99m was injected and patients rapidly returned to their prior position in the magnet for post-exercise cine and perfusion imaging. The patient table was pulled out of the magnet for recovery monitoring. The patient was sent back into the magnet for recovery cine and resting perfusion followed by delayed post-gadolinium imaging. Post-CMR, patients went to the adjacent SPECT lab to complete stress nuclear imaging. Each modality's images were reviewed blinded to the other's results.

RESULTS

Patients completed on average 9.3 +/- 2.4 min of the Bruce protocol. Stress cine CMR was completed in 68 +/- 14 sec following termination of exercise, and stress perfusion CMR was completed in 88 +/- 8 sec. Agreement between SPECT and CMR was moderate (kappa = 0.58). Accuracy in eight patients who underwent coronary angiography was 7/8 for CMR and 5/8 for SPECT (p = 0.625). Follow-up at 6 months indicated freedom from cardiovascular events in 29/29 CMR-negative and 33/34 SPECT-negative patients.

CONCLUSIONS

Exercise stress CMR including wall motion and perfusion is feasible in patients with suspected ischemic heart disease. Larger clinical trials are warranted based on the promising results of this pilot study to allow comparative effectiveness studies of this stress imaging system vs. other stress imaging modalities.

Cardiac function and myocardial perfusion immediately following maximal treadmill exercise inside the MRI room

Treadmill exercise stress testing is an essential tool in the prevention, detection, and treatment of a broad spectrum of cardiovascular disease. After maximal exercise, cardiac images at peak stress are typically acquired using nuclear scintigraphy or echocardiography, both of which have inherent limitations. Although CMR offers superior image quality, the lack of MRI-compatible exercise and monitoring equipment has prevented the realization of treadmill exercise CMR. It is critical to commence imaging as quickly as possible after exercise to capture exercise-induced cardiac wall motion abnormalities. We modified a commercial treadmill such that it could be safely positioned inside the MRI room to minimize the distance between the treadmill and the scan table. We optimized the treadmill exercise CMR protocol in 20 healthy volunteers and successfully imaged cardiac function and myocardial perfusion at peak stress, followed by viability imaging at rest. Imaging commenced an average of 30 seconds after maximal exercise. Real-time cine of seven slices with no breath-hold and no ECG-gating was completed within 45 seconds of exercise, immediately followed by stress perfusion imaging of three short-axis slices which showed an average time to peak enhancement within 57 seconds of exercise. We observed a 3.1-fold increase in cardiac output and a myocardial perfusion reserve index of 1.9, which agree with reported values for healthy subjects at peak stress. This study successfully demonstrates in-room treadmill exercise CMR in healthy volunteers, but confirmation of feasibility in patients with heart disease is still needed.

Receiver operating characteristic (ROC) curves and the definition of threshold levels to diagnose coronary artery disease on electrocardiographic stress testing. Part I: The use of ROC curves in diagnostic medicine and electrocardiographic markers of ischaemia

A common problem in diagnostic medicine, when performing a diagnostic test, is to obtain an accurate discrimination between 'normal' cases and cases with disease, owing to the overlapping distributions of these populations. In clinical practice, it is exceedingly rare that a chosen cut point will achieve perfect discrimination between normal cases and those with disease, and one has to select the best compromise between sensitivity and specificity by comparing the diagnostic performance of different tests or diagnostic criteria available. Receiver operating characteristic (or receiver operator characteristic, ROC) curves allow systematic and intuitively appealing descriptions of the diagnostic performance of a test and a comparison of the performance of different tests or diagnostic criteria. This review will analyse the basic principles underlying ROC curves and their specific application to the choice of optimal parameters on exercise electrocardiographic (ECG) stress testing. Part I will focus on theoretical description and analysis along with reviewing the common problems related to the diagnosis of myocardial ischaemia by means of exercise ECG stress testing. Part II will be devoted to applying ROC curves to available diagnostic criteria through the analysis of ECG stress test parameters.

Usefulness of detectable levels of troponin, below the 99th percentile of the normal range, as a clue to the presence of underlying coronary artery disease

The aim of the study was to evaluate whether markers of myocardial injury and ischemia are helpful in detecting coronary artery disease (CAD) in patients with stable angina. Venous blood was obtained before and after a bicycle exercise test in 47 outpatients with suspected CAD for measurement of cardiac troponin I (cTnI), heart-type fatty acid binding protein, and glycogen phosphorylase BB. Patients with a coronary artery stenosis >/=70% in diameter (n = 33) were compared with patients with coronary narrowing <50% (controls, n = 14). None of the markers increased after bicycle exercise testing. cTnI measured before and after exercise was higher in the CAD group than in controls (p <0.001). The area under the curve for diagnosis was greater when the cTnI value was detectable than with stress testing alone. In conclusion, baseline cTnI was of value in detecting CAD and also during follow-up in predicting the need for further revascularization.

Mechanisms of exercise-induced ST-segment depression in patients without typical angina pectoris

OBJECTIVE

To evaluate if exercise-induced ST-segment depression without typical angina pectoris is related to increases in sympatho-adrenal activity or beta-adrenoceptor sensitivity.

PATIENTS

Thirteen patients (four men) aged 35-62 years with ST-segment depression during exercise but atypical symptoms and normal myocardial scintigraphy, and 13 matched controls.

DESIGN AND INTERVENTIONS

Patients and controls were compared regarding responses with: (i) exercise testing without treatment, (ii) exercise testing following beta-adrenoceptor blockade by propranolol (0.15 mg kg(-1) i.v.), (iii) incremental adrenaline infusions (0.1, 0.2, 0.4 and 0.8 nmol kg(-1) min(-1)) and (iv) adrenaline infusions during alpha-adrenoceptor blockade by phentolamine (0.5 mg min(-1)).

MAIN OUTCOME MEASURES

ST-segment depression and tissue Doppler parameters reflecting contractility.

RESULTS

Exercise lowered the ST-segment by 2.44 mm without and 0.87 mm with beta-adrenoceptor blockade (P < 0.001 for difference) amongst patients, but not amongst controls. Maximal heart rate was slightly higher amongst patients (P < 0.05), despite similar loads and plasma catecholamine responses to exercise in the two groups; this difference disappeared after beta-adrenoceptor blockade with propranolol. ST-segment depression during adrenaline infusion was greater in patients compared with controls (P < 0.01) despite similar increases in heart rate. alpha-Blockade enhanced the ST-segment depression (P < 0.001) and heart rate (P < 0.001) responses to adrenaline infusion more markedly amongst patients. Tissue Doppler imaging showed similar contractility and diastolic relaxation responses of patients and controls to adrenaline, but early diastolic movements did not increase amongst patients after phentolamine (P < 0.01).

CONCLUSIONS

Exercise-induced ST-segment depression in patients with a low likelihood of ischaemic heart disease is related to increased beta-adrenergic sensitivity regarding chronotropic and electrophysiological, but not inotropic responses.

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.

Noninvasive assessment of coronary artery disease in diabetic patients: The role of stress echocardiography

Diabetes mellitus is a frequently occurring disease, and its prognosis is essentially related to cardiac complications. Some have suggested that these patients should be considered as coronary artery disease (CAD)-equivalent and treated aggressively, accordingly. In addition, CAD in diabetes patients at the time of diagnosis is often more advanced, and is frequently associated with more extensive disease, a greater incidence of left ventricular dysfunction and higher rates of cardiac events. Unfortunately, the standard exercise treadmill stress test has important limitations, with a poor sensitivity for CAD detection if the patient has limited exercise capacity, which is the case for more than one-half of the diabetic patients in some series. The detection of regional wall motion abnormality with echocardiography permits the identification of the coronary territory involved. It can be used for CAD diagnosis, evaluation of myocardial viability, risk stratification following a myocardial infarction and assessment of preoperative risk before noncardiac surgery. The risk of CAD in patients with diabetes mellitus is reviewed, and the role of noninvasive testing with stress echocardiography in the diagnosis and risk stratification of these patients is discussed.

Quantitative relation of ST-segment depression during exercise to the magnitude of myocardial ischemia as assessed by single-photon emission computed tomographic myocardial perfusion imaging

The mechanism of ST-segment depression during exercise electrocardiographic treadmill testing (ETT) is unknown. The relatively good correlation between the results of ETT and myocardial perfusion imaging suggests that ST-segment depression may be related to the magnitude of ischemia. Previous studies that investigated this relation have produced conflicting results. We evaluated 1,006 patients who underwent symptom-limited ETT and technetium-99m single-photon emission computed tomographic myocardial perfusion imaging at rest and during stress at a single institution. The magnitude, extent, and duration of ST-segment depression were each strongly associated with the magnitude of myocardial ischemia (p <0.001 for all). The magnitude, extent, and duration of ST-segment depression were highly correlated with each other and had similar relations to the magnitude of ischemia. After adjustment for significant clinical and ETT parameters, these relations remained highly significant. The location of myocardial ischemia was unrelated to ST-segment depression. This large study found that ST-segment depression during ETT is strongly associated with the magnitude of ischemia. These data support a causative role for the magnitude of ischemia in the generation of ST-segment depression.

Detecting occult coronary disease in a high-risk asymptomatic population

BACKGROUND

Exercise stress testing alone or with perfusion imaging is the standard screening method to determine the presence of obstructive coronary artery disease (CAD) in people with chest pain. In asymptomatic individuals with a family history of premature CAD, it is unclear whether abnormalities on these functional exercise tests represent significant coronary disease.

METHODS AND RESULTS

An abnormal exercise test, thallium scan, or both occurred in 153 (21%) of 734 asymptomatic siblings of persons with documented CAD, of whom 105 underwent coronary angiography with quantitative analysis of stenosis severity. Overall, 95% had coronary atherosclerosis, but only 39% had 1 or more stenoses with >or=50% narrowing. Of 30 siblings in whom the exercise test and perfusion scan were both abnormal, 70% had >or=50% stenoses. The mean stenosis in arteries that fed perfusion defects was only 43+/-31%, and 68% of such stenoses were <50%. However, in 71% of all defects, the location matched arteries with the most severe stenoses.

CONCLUSIONS

In asymptomatic persons with a family history of CAD, abnormal exercise scintigraphy identifies predominantly mild coronary atherosclerosis. Perfusion defects may be caused by coronary vasomotor dysfunction in addition to atherosclerotic plaque.