Clinical competence in exercise testing. A statement for physicians from the ACP/ACC/AHA Task Force on Clinical Privileges in Cardiology

Evaluating current assessment techniques of cardiorespiratory fitness

INTRODUCTION

Considerable and convincing global data from cohorts across the health spectrum (i.e. apparently healthy to known disease) indicate that cardiorespiratory fitness (CRF) is a major predictor of overall and cardiovascular disease (CVD)-survival, seemingly with greater prognostic resolution compared to other traditional CVD risk factors. Therefore, the assessment of CRF in research and clinical settings is of major importance.

AREAS COVERED

In this manuscript, we review the technology of measuring CRF assessed by the 'gold standard,' cardiopulmonary exercise testing (CPET), as well as with various other methods (e.g. estimated metabolic equivalents, 6-minute walk tests, shuttle tests, and non-exercise equations that estimate CRF), all of which provide significant prognostic information for CVD- and all-cause survival. The literature through May 2024 has been cited.

EXPERT OPINION

The promotion of physical activity in efforts to improve levels of CRF is needed throughout the world to improve lifespan and, more importantly, healthspan. The routine assessment of CRF should be considered a vital sign that is routinely assessed in clinical practice.

Exercise Testing in Asymptomatic Aortic Stenosis

AIMS

To determine the safety of exercise testing (ET) in patients with moderate or severe asymptomatic aortic stenosis (AAS) and its accuracy to predict the need for surgery and mortality.

METHODS

106 consecutive patients with AAS performed a maximal ET.

RESULTS

Follow-up [10.7 (4.9-19.4) months (percentile 25-75)] was completed in 102 patients (96.2%), 63.9 years (+/-15.1), 65 (61.3%) male, peak gradient 82.8 mm Hg (+/-25.4), mean gradient 50.5 mm Hg (+/-16.6), valve area 0.67 cm(2) (+/-0.16); 67 patients (65.7%) had abnormal ET. Among the 35 patients with normal ET, there were no deaths and 10 aortic valve replacements (AVR) (28.5%) were performed. Among the 67 patients with abnormal ET, 37 (55.2%) had events (35 AVR and 2 died) (p <0.0001). There were no complications with ET.

CONCLUSION

ET may be performed safely in patients with AAS. ET gives additional information to an AVR decision.

A Pilot Study of the Clinical Impact of Hand-Carried Cardiac Ultrasound in the Medical Clinic

BACKGROUND

Small, hand-carried ultrasound devices have become widely available, making point-of-care echocardiograms (echos) accessible to all medical personnel as a means to augment and improve the increasingly inefficient physical examination. This study was designed to determine the clinical utility of hand-carried echo by medical residents in clinical decision making.

METHODS

Nine residents underwent brief, practical echo training to perform and interpret a limited hand-carried echo as an integral component of their office examination. The residents' hand-carried echo consisting of four basic views to define left ventricular (LV) function and wall thickness, valvular disease, and any pericardial effusions was compared to one performed by a level III echocardiographer.

RESULTS

Seventy-two consecutive medical clinic patients were enrolled with an average image acquisition time of 4.45 minutes. Residents obtained diagnostic images in 94% of the cases and interpreted them correctly 93% of the time. They correctly identified 92% of the major echo findings and 78% of the minor findings. Their diagnosis of LV dysfunction, valvular disease, and LV hypertrophy improved by 19%, 39%, and 14% with hand-carried echo compared to history and physical alone. Management decisions were reinforced in 76% and changed in 40% of patients with the use of hand-carried echo.

CONCLUSION

This study demonstrates that it is possible to train medical residents to perform an effective and reasonably accurate hand-carried echo during their physical examination, which can impact clinical management.

Prognostic importance of presenting symptoms in patients undergoing exercise testing for evaluation of known or suspected coronary disease

PURPOSE

Chest symptoms, along with standard cardiovascular risk factors, are commonly factored into pretest risk stratification of patients who are referred for stress testing. We sought to determine the independent prognostic value of chest symptoms.

METHODS

We studied the outcomes of 10,870 patients referred for symptom-limited exercise testing who had no history of myocardial revascularization, heart failure, or arrhythmias. Chest symptoms were prospectively characterized according to prespecified definitions. Propensity analysis was used to account for differences in baseline and exercise characteristics.

RESULTS

Typical angina was present in 635 patients (6%), atypical angina in 3408 (33%), nonanginal chest pain in 1805 (17%), and dyspnea in 841 (8%). The remaining 4181 patients (38%) were asymptomatic. During a mean follow-up of 4.3 years, there were 381 deaths. After propensity matching patients who had typical angina with asymptomatic patients, symptoms were not predictive of mortality (adjusted hazard ratio [HR] = 0.8; 95% confidence interval [CI]: 0.6 to 1.3; P = 0.4). Among patients who had chest pain, typical angina was associated with a highly significant risk of mortality as compared with nonanginal chest pain (HR = 2.7; 95% CI: 1.4 to 5.1; P = 0.002), but not compared with atypical angina (HR = 1.3; 95% CI: 0.9 to 2.1; P = 0.21).

CONCLUSION

After accounting for baseline and exercise characteristics, the presence of symptoms was not independently associated with increased mortality among patients undergoing testing for known or suspected coronary disease. Among patients who actually had chest pain, typical angina carried a higher mortality risk.

Exercise stress testing. An overview of current guidelines

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

Is nurse-supervised exercise stress testing safe practice?

OBJECTIVE

Nurses have been performing exercise stress tests (EST) without medical supervision since 1978 in our hospital-based cardiac rehabilitation unit. This study was conducted to examine the incidence of cardiovascular complications and to describe the competency-based training program for the nurses performing the EST.

DESIGN

Descriptive, retrospective audit of prospective data.

SETTING

Single comprehensive cardiac rehabilitation center in a large tertiary referral hospital in western Sydney, Australia.

SUBJECTS

Seventeen thousand, four hundred and sixty-seven patients were included in this study over a 12-year period.

METHOD

Data were collected on all ESTs performed by the cardiac rehabilitation nurses from January 1986 to December 1997 in relation to serious cardiovascular complications and other EST parameters.

RESULTS

In this study, 17,467 ESTs were performed on 5054 patients who had 6273 separate presentations. The most common entry diagnosis was after an acute myocardial infarction (50%). The mean age was 58 +/- 10.5 years (range 15 to 87 years; 80% male). The left ventricular ejection fraction (n = 2822) was 49% +/- 14%. In a subgroup analysis of 14,454 patients, 14% had a positive EST (ST segment >1.9 mm depression). There were no deaths associated with the EST, and there were 13 major complications in 12 patients. This figure included no cardiac arrests, 11 episodes of conscious sustained ventricular tachycardia, 1 reinfarction, and 1 mitral valve rupture, representing a 0% mortality rate and a 0.075% major morbidity rate.

CONCLUSION

This study shows that nurse-supervised EST of higher risk patients in the hospital-based cardiac rehabilitation setting has been a safe practice from a mortality and morbidity rate perspective. This finding may be accounted for by the high training standard and reaccreditation of the nurses on the advanced practice of performing EST.

Carotid artery disease as a marker for the presence of severe coronary artery disease in patients evaluated for chest pain

BACKGROUND AND PURPOSE

We sought in this study to elucidate whether carotid artery disease detected by ultrasonography can be a clinically useful marker for the presence of severe coronary artery disease (CAD) in patients evaluated for chest pain.

METHODS

Duplex ultrasonography and quantitative coronary angiography were used to assess carotid and coronary artery atherosclerosis in 225 consecutive patients (mean age, 58+/-9 years) with chest pain referred for cardiac catheterization.

RESULTS

CAD was present in 197 patients (88%). Fifty-seven patients (25%) had 1-vessel disease, 52 (23%) had 2-vessel disease, 53 (24%) had 3-vessel disease, and 35 (16%) had left main stem CAD (LMS-CAD). The incidence of severe CAD (3-vessel disease or LMS-CAD) was 24% and 63% in the normal and impaired ejection fraction (EF) subgroups, respectively (P<0.005). Carotid disease (lumen diameter stenosis of >/=50%) was present in 5.3%, 13.5%, 24.5%, and 40% of patients with 1-, 2-, and 3-vessel disease and LMS-CAD, respectively. Moreover, the incidence of carotid disease in patients with severe CAD was 31% in the entire study population and 46% and 5% in the subgroups with impaired and normal EF, respectively (P<0.005). In the entire study population, the presence of severe CAD was determined by age, male sex, and carotid disease; in the impaired EF group by age and carotid disease; and in the normal EF group only by age. Carotid disease has a high negative (92%) and a high positive (91%) predictive value for the presence of severe CAD in the subgroup with normal and impaired EF, respectively.

CONCLUSIONS

In patients evaluated for chest pain, carotid disease is significantly correlated with severe CAD. Furthermore, in patients with impaired left ventricular systolic performance the presence of carotid disease reflects the presence of severe CAD, while in patients with normal EF the absence of carotid disease reflects the absence of severe CAD.

Association of increased QT dispersion with coronary atherosclerosis in patients with aortic stenosis

To evaluate correlates between electrocardiographic QT dispersion and coronary atherosclerosis in patients with aortic stenosis before aortic valve replacement, 39 consecutive patients >40 years old with symptomatic aortic stenosis and coronary diameter narrowing > or =50% measured by digital angiographic study were included. An additional matched group with insignificant coronary lesions (<50%) consisted of 39 patients for comparisons. Matching by age, sex heart rate and incidence of chest pain resulted in two comparable groups with identical baseline characteristics. Preoperative transthoracic echocardiography and electrocardiograms were performed in all subjects. QT dispersion was defined as the difference between maximal and minimal QT interval measurements occurring among any of the 12 leads on a standard electrocardiogram. No subject had fewer than nine measurable leads. There were no significant differences of risk factors of coronary artery disease between the two groups. From a conditional multivariate logistic regression analysis, independent predictors of development of coronary artery disease in aortic stenosis were only QTc dispersion (odds ratio= 1.255, P=0.01). A wide QTc dispersion > or =70 ins) correlated with the presence of angiographically significant coronary artery disease with a sensitivity and specificity of 72% and 79%. The positive accuracy of having significant coronary artery disease in the presence of QTc dispersion > or =70 ms was 78%. The negative predictive value was 74%. In conclusion, electrocardiographic QTc dispersion may provide important clinical information. A wide QTc dispersion in patients with aortic stenosis is associated with a high incidence of coronary artery disease. These findings warrant further investigation in a large trial.

Safety of dobutamine stress echocardiography supervised by registered nurse sonographers

Dobutamine stress echocardiography (DSE) is widely used for the diagnosis and evaluation of coronary artery disease. Studies examining the safety of this technique typically have involved DSE supervised by physicians. At the Mayo Clinic, experienced registered nurse (RN) sonographers were trained to perform DSE under the direct supervision of a physician. To prove that the safety of DSE was not compromised with the change in supervision, we examined data from 1035 consecutive outpatient studies: 516 patients were monitored by cardiologists or cardiology fellows (group 1) and 519 were monitored by trained RN sonographers (group 2). Risk factors, history of coronary artery disease, stress parameters, and complication rates were similar in both groups. In group 1, one patient experienced sustained ventricular tachycardia requiring treatment. In group 2, one patient experienced ventricular fibrillation during recovery and was successfully resuscitated. Outpatient DSE is safe when supervised by RN sonographers.

Maximal exercise hemodynamics and risk of mortality in apparently healthy men and women

The purpose of this investigation was to determine the association of maximal exercise hemodynamic responses with risk of mortality due to all-causes, cardiovascular disease (CVD), and coronary heart disease (CHD) in a population of apparently healthy individuals. Study participants were 20,387 men (mean age = 42.2 yr) and 6,234 women (mean age = 41.9 yr), patients of a preventive medicine center in Dallas, TX, examined between 1971 and 1989. Maximal heart rate and maximal systolic blood pressure (SBP) measured during the maximal exercise test were related to risk of all-cause, CVD, and CHD mortality. During an average of 8.1 yr of follow-up, there were 348 deaths in men and 66 deaths in women. Among men, after adjustment for confounding variables, risks (and 95 percent confidence interval (CI)) of all-cause mortality for quartiles of maximal SBP, relative to the lowest quartile, were: 0.96 (0.70-1.33), 1.36 (1.01-1.85), and 1.37 (0.98-1.92) for quartiles 2-4, respectively. Similarly adjusted risks for maximal heart rate were: 0.61(0.44-0.85), 0.69 (0.51-0.93), and 0.60 (0.41-0.87). Similar results were seen for risk of CVD and CHD death. In women, similar trends in adjusted risks of all-cause and CVD mortality across maximal SBP and heart rate categories were observed. For maximal heart rate, a 35 bpm higher value was associated with a 36 percent decreased risk of CVD mortality in men (RR = 0.63,95 percent CI = 0.34-0.71) and an 8 percent lower risk in women (RR = 0.92,95 percent CI = 0.18-4.63). These results suggest that an exaggerated SBP or an attenuated heart rate response to maximal exercise may indicate an elevated risk for mortality in this apparently healthy population.

Current status of myocardial perfusion imaging after percutaneous transluminal coronary angioplasty

Controversy exists with regard to the diagnostic accuracy and optimal technique of myocardial perfusion imaging after coronary angioplasty. Exercise treadmill testing is inexpensive, with adequate predictive value for restenosis and clinical events in patients with single-vessel coronary angioplasty with a normal rest electrocardiogram (ECG). Myocardial tomography has advantages for assessing patients with multivessel coronary angioplasty. Exercise stress imaging is generally preferable to pharmacologic stress in patients without physical limitations after angioplasty. Delayed thallium-201 imaging and reinjection protocols may be useful to reconcile whether residual ischemia exists in "fixed" perfusion defects. Appropriately timed stress myocardial perfusion imaging 2 to 4 weeks after procedurally successful coronary angioplasty can document improved cardiac functional capacity and reduced ECG and imaging evidence of myocardial ischemia. Although routine serial postangioplasty evaluations cannot be recommended, stress myocardial imaging may be valuable in subjects with defective anginal nociception or extensive myocardium at risk in the area subtended by the angioplasty vessel.

Guidelines for physician training in advanced cardiac procedures: the importance of case mix

In recent years, guidelines have been issued for the standardization of physician training in various advanced cardiac procedures. One area that is often neglected by guidelines committees is the need for an adequate case mix during physician training. Case mix refers to the variety of patients and diseases that the trainee is exposed to during the course of learning a new procedure. Although physicians may perform the requisite number of procedures during their training, if the case mix is inadequate, the physician's competence in performing the procedure and interpreting its results may be inadequate as well.

Tachycardia and coronary blood flow: non-invasive estimation during Valsalva manoeuvre and exercise

Simultaneous changes in cycle length and coronary blood flow were studied during Valsalva manoeuvre and supine cycloergometer exercise test in 10 male patients (mean age 48 +/- 12 years) who had successfully undergone myocardial revascularization by surgical anastomosis of the left internal mammary artery on the left anterior descending coronary artery. Blood velocity curves in the left internal mammary artery were obtained by a non-invasive continuous-wave Doppler probe at rest, in the last phase of the expiratory effort of the Valsalva manoeuvre and at the maximum load attained during the exercise test. Mean arterial pressure by sphygmomanometer, and cardiac cycle length on the basis of Doppler recording were measured. Mean blood velocity, the length of the blood column entering the coronary bed at each cycle (cardiac cycle times mean velocity), an index of blood cell acceleration (the ratio of mean velocity to cardiac cycle), and an index of coronary resistance (the ratio of mean pressure to mean velocity), were calculated. For approximately the same change in cycle length, coronary resistance decreased in exercise, with an increased mean velocity, but increased in Valsalva, with no changes in mean velocity. The length of the blood column entering the coronary bed at each cycle was unchanged in exercise, with a marked increase in the acceleration index, while it decreased in Valsalva. Therefore, we hypothesize that tachycardia has a limiting effect on sympathetic coronary constriction in Valsalva when cardiac external work is decreased, and an additional vasodilatory effect on coronary bed in exercise when external work is increased.

Exclusion of coronary artery disease by exercise thallium-201 tomography in patients with aortic valve stenosis

In many patients with valvular aortic stenosis (AS), management decisions may be possible without invasive studies if coexistent coronary artery disease (CAD) can be ruled out noninvasively. The use of thallium-201 single-photon emission computed tomography to the exclusion of CAD was studied in 44 patients aged 41 to 78 years with AS. In addition to cardiac catheterization and selective coronary angiography, patients underwent a cardiac ultrasound study and thallium-201 myocardial perfusion imaging at rest and after bicycle ergometer exercise. Two thirds of the patients had critical AS (valve area index less than or equal to 0.5 cm2/m2) but none had left ventricular systolic dysfunction. Twenty-one patients had angiographically significant CAD (greater than or equal to 50% diameter stenosis in greater than or equal to 1 coronary artery), whereas 23 had either a fully normal angiogram (n = 17) or mild (less than 50%) stenoses (n = 6). Each patient with significant CAD had an abnormal thallium-201 tomogram, either a strictly segmental perfusion defect (n = 19), or a patchy nonsegmental abnormality (n = 2); however, 10 of 23 patients free of significant CAD had similar results. Thus, the sensitivity and specificity of an abnormal scintigram were 100 and 57%, respectively. If only segmental perfusion defects typical of CAD had been considered abnormal, then the sensitivity of the test would have been 90% and the specificity 70%. Patients with false abnormal scintigrams had more severe AS and more angiographically nonsignificant CAD than those with true normal findings.(ABSTRACT TRUNCATED AT 250 WORDS)

Systemic and left ventricular responses to exercise stress in asymptomatic patients with valvular aortic stenosis

Patients with heart disease may have myocardial ischemia or left ventricular (LV) dysfunction without symptoms. The exercise responses of 14 asymptomatic patients with valvular aortic stenosis (AS) were studied using treadmill testing, thallium-201 scintigraphy and radionuclide angiography. Compared with age- and gender-matched control subjects, patients with AS demonstrated reduced exercise tolerance (10.7 +/- 2.5 vs 13.3 +/- 4.2 min; p = 0.06) and maximal oxygen consumption (26.7 +/- 6.3 vs 36.3 +/- 9.5 ml O2/min/kg; p = 0.004) associated with decreased peak systolic blood pressure response to exercise (177 +/- 18 vs 214 +/- 42 mm Hg; p less than 0.004). Ten of 14 patients developed ST-segment depression during exercise, only 3 of whom had reversible thallium defects. Patients with AS tended to have greater LV ejection fractions at rest (65 +/- 11 vs 58 +/- 7; p = 0.08) and significantly decreased early peak filling rates (4.8 +/- 1.3 vs 6.1 +/- 0.6 stroke volume/s; p = 0.003) compared with those of control subjects. During maximal supine exercise, patients with AS had less of an increase in ejection fraction (2 +/- 9 vs 15 +/- 7%; p less than 0.001) associated with a decrease in end-diastolic (-7 +/- 15 vs +5 +/- 16%; p = 0.06) and stroke (-6 +/- 17 vs +30 +/- 13%; p less than 0.001) volumes from baseline measurements.(ABSTRACT TRUNCATED AT 250 WORDS)