Use of exercise testing for diagnostic and functional evaluation of patients with arteriosclerotic heart disease

Dobutamine stress MRI. Part I. Safety and feasibility of dobutamine cardiovascular magnetic resonance in patients suspected of myocardial ischemia

The aim of the study was to evaluate safety and feasibility of dobutamine cardiovascular magnetic resonance (CMR) in patients with proven or suspected coronary artery disease. Dobutamine CMR was evaluated retrospectively in 400 consecutive patients with suspicion of myocardial ischemia. Dobutamine was infused using an incremental protocol up to 40 microg/kg body weight per minute. All anti-anginal medication was stopped 4 days before the CMR study and infusion time of dobutamine was 6 min per stage. Hemodynamic data, CMR findings and side effects were reported. Patients with contraindications to CMR (metallic implants and claustrophobia) were excluded from analysis. Dobutamine CMR was successfully performed in 355 (89%) patients. Forty-five (11%) patients could not be investigated adequately because of non-cardiac side effects in 29 (7%) and cardiac side effects in 16 (4%) patients. Hypotension (1.5%) and arrhythmias (1%) were the most frequent cardiac side effects. One patient developed a severe complication (ventricular fibrillation) at the end of the study. There were no myocardial infarctions or fatal complications of the stress test. The most frequent non-cardiac side effects were nausea, vomiting and claustrophobia. Age >70 years, prior myocardial infarction and rest wall motion abnormalities showed no significant differences with side effects (P>0.05). Dobutamine CMR is safe and feasible in patients with suspicion of myocardial ischemia.

Comparative study of dobutamine stress electron-beam computed tomography and exercise thallium scintigraphy in the diagnosis of patients with suspected coronary artery disease

To evaluate the diagnostic value of dobutamine stress electron-beam computed tomography (EBCT) as compared with exercise stress thallium-201 single-photon emission computed tomography (201T1-SPECT) for the detection of myocardial ischemia, 10 patients with proven or suspected coronary artery disease underwent both tests. Nine of the 10 patients also underwent coronary angiography. EBCT images were analyzed objectively to evaluate systolic wall thickening and analyzed segmentally to determine the distribution of the coronary arteries. Dobutamine stress EBCT revealed the presence of ischemia in 59 segments, whereas exercise stress 201T1-SPECT revealed ischemia in 51 segments (agreement = 73%). The advantage of dobutamine stress EBCT was demonstrated in the inferior/posterior segments as compared with the results of exercise stress 201T1-SPECT. The overall sensitivity for detecting ischemic regions supplied by coronary arteries with significant stenosis (diameter stenosis > 50%) was 83% for dobutamine stress EBCT and 79% for exercise stress 201T1-SPECT (p = NS), with specificities of 75% and 82% (p = NS). Thus, dobutamine stress EBCT presents a reasonable alternative to exercise stress 201T1-SPECT for the objective assessment of patients with suspected coronary artery disease.

Direct access exercise electrocardiography: a new service that improves the management of suspected ischaemic heart disease in the community

OBJECTIVE

To assess the safety and value of an exercise electrocardiography service for the diagnosis of suspected ischaemic heart disease to which general practitioners have direct access.

DESIGN

Direct access to a hospital exercise electrocardiography service was offered on a trial basis to 122 general practitioners in a defined urban area. Maximal exercise tests were performed according to the modified Bruce protocol and the results were dispatched promptly to the referring doctors who were responsible for the subsequent management of their patients.

SETTING

All general practices in north and west Belfast (combined list size about 180,000) and the regional medical cardiology centre.

PATIENTS

212 request forms were received in a two year period and 192 eligible patients attended for exercise testing. All patients were suspected to have pain due to myocardial ischaemia, were aged < or = 65, and had no contraindications to exercise testing.

MAIN OUTCOME MEASURES

Proportion of general practitioners who used the service. Proportion of exercise tests that were positive. Referring doctors' assessment of the service.

RESULTS

43% of general practitioners referred patients and 34 tests (18%) were positive. No complications occurred. The pretest likelihood of ischaemic heart disease, assessed by the referring doctor, was high in 48 (25%), moderate in 82 (43%), and low in 62 (32%). A high pretest likelihood of ischaemic heart disease predicted a positive test result with a sensitivity of 50% and specificity of 80%. General practitioners decided to refer 19 (10%) patients to a hospital cardiology department for further assessment, including 16 of the 34 who had a positive exercise test. In most cases the service was found to be helpful and 97% of patients would have been referred directly to a hospital cardiology clinic if it had not been available.

CONCLUSIONS

Direct access exercise electrocardiography for patients with suspected ischaemic heart disease is safe, feasible, and helpful to general practitioners. This service seems to reduce the number of patients referred to cardiology outpatient clinics and to facilitate the management of these patients in the community.

Open Access Exercise Electrocardiography: A Service to Improve Management of Ischaemic Heart Disease by General Practitioners

An initial study of the use of open access exercise electrocardiography by general practitioners (GPs) in South East Kent showed that patient selection and interpretation of test results was frequently incorrect. After issuing guidelines, modifying the request form and instituting registrar review of all requests, significant improvements in both referral pattern, result interpretation and patient management have resulted.

Forty-nine GPs requested 110 exercise tests during 1988/89. Twelve per cent were not undertaken after discussion with the referring practitioner. Eighty-four per cent of those tested would have been referred to the district general hospital cardiology outpatient department in the absence of open access exercise electrocardiography service. Six per cent of patients were referred directly for invasive investigation. Thirty-five per cent were referred to the district general hospital cardiology outpatient department, whilst 42% were spared hospital referral based on the result of the investigation.

Better use of the modified service was suggested by: Referral of fewer patients with non-cardiac chest pains (P= 0.002); more patients with a moderate pre-test probability of ischaemic heart disease (P<0.05); fewer inappropriate requests (P<0.01); and fewer inappropriately undertaken tests (P< 0.001) than in the previous study. All patients with strongly positive test results were appropriately managed.

Open access exercise electrocardiography in the format investigated is potentially a cost-effective and useful tool to improve diagnosis and management of heart disease bv GPs.

Dipyridamole perfusion scintigraphy: the experience with its application in one hundred seventy patients with known or suspected unstable angina

We evaluated the safety, accuracy, and potential clinical utility of intravenous dipyridamole perfusion scintigraphy with thallium-201 in 170 patients, 78 with suspected and 92 with known unstable angina. All had coronary angiography. Noncardiac side effects (26%), induced chest discomfort (44%), and ST segment changes (12%) were similar in the two groups. No significant arrhythmias occurred. Two patients had prolonged chest pain, both with extensive reversible image abnormalities and associated creatinine kinase-MB release. Both had elective bypass surgery. Twenty-eight patients had normal coronary arteries, and 35 had single-vessel disease. Scintigraphic per patient sensitivity and specificity were 91% and 79% with a per vessel sensitivity of 74% and a per vessel specificity of 78% without between-group differences. During a brief follow-up period, 62 patients with image abnormalities had coronary revascularization, and there were seven deaths without intergroup differences. In a similar patient group that did not have angiography, scintigraphic defects were less frequent and less extensive, revascularization was not performed, and subsequent deaths occurred less often. Dipyridamole perfusion scintigraphy is an accurate alternative to exercise testing in the evaluation of patients with unstable angina pectoris. Although not without risk, the method appears relatively safe and should be considered as a guide to diagnosis, and probably to prognosis and management.

Improvement in rest and exercise-induced wall motion abnormalities after coronary angioplasty: an exercise echocardiographic study

Exercise echocardiography was performed in 36 patients to evaluate functional improvement after coronary angioplasty. Thirty-one patients (86%) had provokable ischemia before angioplasty including 22 with an abnormal exercise electrocardiographic test (angina or ST depression), 25 with an abnormal exercise echocardiogram (exercise-induced wall motion abnormalities) and 16 with both tests abnormal. Nineteen patients had no induced ischemia after angioplasty. Seventeen (47%) continued to have ischemia that was limited in 12 to exercise-induced wall motion abnormalities, which were less severe compared with those of preangioplasty studies. Fifteen (65%) of 23 patients had improvement in rest wall motion abnormalities after angioplasty. The rest to immediate postexercise change in global wall motion score was significantly improved after angioplasty. The change in regional wall motion score was significantly improved after angioplasty in patients with single vessel right or left circumflex coronary artery disease and approached significant improvement (p = 0.06) in those with single vessel disease of the left anterior descending coronary artery. Exercise echocardiography improves the sensitivity of functional testing for ischemia, aids in localizing the ischemic zone and documents improvement in regional function after coronary angioplasty.

Open Access Exercise Electrocardiography: Does it Improve the Management of Cardiovascular Disease in the Community?

In this study the use of exercise electrocardiography, by 47 general practitioners in South East Kent has been evaluated.

Of 110 consecutive requests the majority (88%) were for diagnostic purposes, while only 7% were for prognostic assessment. Many of those referred were young or had non-cardiac chest pain and in 59% of cases the test result was unlikely to alter the clinical assessment of the probability of ischaemic heart disease (IHD). The test result influenced patient management in 85% of cases. Only 15% of patients were subsequently referred to the district general hospital although all had been considered for referral prior to the test.

Although referral for invasive investigation of six patients was expedited by the provision of stress testing, in five patients general practitioners failed to consider any further investigation despite the patient having a strongly positive test. General practitioners use exercise electrocardiography primarily to exclude IHD in patients at low risk and provide reassurance. They rarely use the test as a means to guide management of those with known or probable IHD.

Detection of Drug Interactions Involving Radiopharmaceuticals: A Professional Responsibility of the Clinical Pharmacist

Radiopharmaceuticals are radioactive drugs used in nuclear medicine for diagnosis and, to some degree, for the treatment of disease. Considerable evidence exists in regard to the potential for altered biorouting of radiopharmaceuticals resulting from the coadministration of therapeutic drugs, as well as from certain disease states, nutritional conditions, and other factors. Altered biorouting may reduce the usefulness of the diagnostic test or provide misleading information. While retrospective identification of an altered biodistribution problem can be helpful, prospective detection is more desirable and can be achieved by a hospital-based pharmacist. Although most drug-radiopharmaceutical interactions are not beneficial, some nuclear medicine procedures are conducted using drug intervention to enhance the diagnostic efficacy of the test. Also, nuclear medicine procedures may be used to monitor the outcome of a therapeutic regimen or to aid in determining the pharmacologic effect of an investigation drug. While not covering the full scope of the area, the material in this chapter is intended to provide an introduction to the problems and opportunities associated with drug-radiopharmaceutical interactions and to stimulate pharmacists to provide clinical pharmacy services to nuclear medicine.

The effects of nitroglycerin on regional myocardial contractile dysfunction produced by treadmill exercise or isoprenaline stimulation in dogs

1. To compare different methods of cardiac stress testing that are clinically applied in the management of coronary heart disease, 2 groups of dogs each were chronically instrumented and subjected to treadmill exercise or isoprenaline infusion in the presence of coronary stenosis. 2. It was of interest to determine differences in haemodynamic and regional myocardial contractile parameters, the response to antianginal therapy (nitroglycerin 15 micrograms kg-1 15 min-1, i.v.), and, in particular, whether this response differed according to the mode of cardiac stimulation, i.e. treadmill exercise or isoprenaline infusion. 3. After stenosis of the circumflex branch of the left coronary artery which affected resting myocardial function only minimally, treadmill exercise or isoprenaline infusion induced transient regional contractile dysfunction. Heart rate, arterial blood pressure, left ventricular end-diastolic pressure and left ventricular dp/dtmax were registered and myocardial oxygen demand was calculated. Regional contractile performance was assessed by ultrasonic distance measurement in the underperfused and in a normally perfused area. 4. Treadmill exercise led to an increase in systolic arterial and left ventricular end-diastolic pressure. In contrast, isoprenaline-induced stimulation led to a decrease in diastolic arterial and left ventricular end-diastolic pressure. Regional contractile function in the critically underperfused area showed a deterioration during both modes of stress. Nitroglycerin completely abolished stress-induced contractile dysfunction only in the group where treadmill exercise was employed for stimulation. 5. The inability of nitroglycerin to prevent myocardial dysfunction in the isoprenaline group may be due to exhaustion of the arterial and/or venous vasodilator potency of nitroglycerin in the presence of adrenoceptor vasodilatation induced by isoprenaline. 6. These findings indicate that clinical antianginal drug testing and the evaluation of the course of disease in patients with coronary heart disease may be highly dependent on the test method chosen.

Effect of gender on left ventricular function during exercise in patients with coronary artery disease

This study evaluated the effect of gender on left ventricular (LV) function in 84 men and 20 women with coronary artery disease (CAD) (greater than or equal to 50% luminal narrowing of one or more of the major coronary arteries). All patients underwent rest and upright exercise radionuclide ventriculography on a bicycle ergometer. There were no differences between men and women in age, hypertension, medications, and extent of CAD disease (number of diseased vessels or CAD score). Although men exercised for a longer duration than women, both achieved similar exercise heart rates and blood pressures. Angina pectoris or ST depression during exercise occurred in similar proportion in both groups. The LV ejection fraction and the systolic pressure-to-end-systolic volume ratio at rest and during exercise were similar in both men and women. Thus, men and women with comparable extent of CAD demonstrate similar manifestations of myocardial ischemia and LV dysfunction during exercise. Gender does not appear to influence LV function independent of the extent of CAD.

Early positive exercise test and extensive coronary disease: effect of antianginal therapy

The effect of antianginal therapy on the incidence of an early positive exercise response as a screening tool for 3-vessel and left main (LM) coronary artery disease (CAD) was examined. Fifty-seven men with stable angina pectoris underwent bicycle ergometry before and after long-acting nitrate or calcium antagonist therapy was instituted. An early positive response was defined as signs of myocardial ischemia at low levels of myocardial and total body workload (corresponding to a workload of less than 300 kpm/min). Thirty-nine patients (68%) had an early positive response before therapy, compared with 14 (24%) after therapy. Of 24 patients undergoing coronary angiography, 12 had 3-vessel CAD (including 2 with LM), 5 had 2-vessel CAD, 6 had 1-vessel CAD and 1 patient had no CAD. The sensitivity and specificity of an early positive response in predicting 3-vessel/LM CAD changed from 92% and 58% before to 42% and 75% after therapy. The positive and negative predictive values changed from 69% and 88% before to 63% and 63% after therapy. It is concluded that antianginal therapy reduces the value of an exercise test as a screening tool for 3-vessel/LM CAD.

Exercise testing of leg amputees and the result of prosthetic training

Thirty-nine patients undergoing rehabilitation following leg amputation were examined to determine cardiac status, which included clinical examination and a graded exercise ECG test, using an arm ergometer. Results were compared to final walking ability. It was found that the cardiac status of these patients was generally poor and that the exercise ECG results did co-relate to walking ability.

Similarity between women and men in manifestation of myocardial ischemia during exercise

We assessed the effect of gender on the electrocardiographic changes and thallium-201 myocardial perfusion during exercise in patients with coronary artery disease. Eighty-nine patients with coronary artery disease (50% or greater diameter narrowing of one or more major coronary arteries) who had undergone exercise thallium scintigraphy were retrospectively studied. There were 29 women and 60 men. Fifty-six patients had one-vessel disease, 11 patients had two-vessel disease, and 22 patients had three-vessel disease or left main disease. The extent of coronary artery disease was assessed by the Gensini score. There was no difference between men and women in age, medications, number of diseased vessels and the coronary artery disease score. Exercise tolerance was lower, although insignificantly in women compared to men. However, exercise heart rate, double product, and the electrocardiographic response were similar in men and women. Also, both the presence and size of exercise-induced perfusion defects were similar in men and women. Thus, the electrocardiographic response to exercise is not influenced by gender in patients with similar extent of coronary artery disease and comparable manifestations of myocardial ischemia.

Prognostic value of submaximal exercise radionuclide ventriculography after myocardial infarction

Submaximal exercise testing with radionuclide ventriculography (RVG) was performed in 117 patients before hospital discharge 17 +/- 7 days (+/- standard deviation) after an acute myocardial infarction (MI). The hypothesis tested in these studies was that submaximal exercise testing coupled to RVG allows the identification of patients at risk for future ischemic events in the subsequent 6 months, irrespective of MI location and type. The sites of MI were characterized as anterior transmural in 33, inferior transmural in 39, limited nontransmural in 18, extensive nontransmural in 24 and indeterminant in 3. During 6 months of follow-up, 9 patients died, 14 had recurrent MI, 18 had refractory angina pectoris, 16 had limiting angina and 17 had congestive heart failure. Discriminant function analysis ranked exercise changes in left ventricular (LV) ejection fraction and end-systolic volume the most important of all clinical, exercise and scintigraphic variables for predicting future cardiac events. The predictive accuracy of changes in LV ejection fraction and end-systolic volume were 93 and 91%, respectively, for the entire group, and were significantly more sensitive than any degree of ST-segment depression or elevation (p less than 0.001). These findings were generally independent of MI location and type. Thus, submaximal exercise RVG after MI is an accurate means of identifying patients at risk for major cardiac events in the 6 months after hospital discharge.

Prognostic value of resting and submaximal exercise radionuclide ventriculography after acute myocardial infarction in high-risk patients with single and multivessel disease

In patients who survive the acute phase of myocardial infarction, those with multivessel coronary artery disease generally have a worse prognosis than those with single-vessel disease. However, some patients with significant multivessel stenoses have a good prognosis, whereas some with a significant single-vessel stenosis have a poor prognosis. Thus, although definition of coronary anatomy may be helpful, it is a not a fail-safe prognosticator. In this retrospective analysis, the association of abnormalities at rest and during submaximal exercise testing with radionuclide ventriculography after acute myocardial infarction with major cardiac complications (death, recurrent infarction, severe angina or congestive heart failure) in the ensuing 6 months was assessed in patients with single and multivessel disease. Coronary angiography and submaximal exercise testing with radionuclide ventriculography were performed within 3 months of each other in 42 patients. Eleven of the 16 patients with single-vessel coronary stenosis had major cardiac complications. The subsequent course of these 16 patients was correctly predicted by left ventricular ejection fraction (LVEF) less than or equal to 0.40 in 8 patients, by LVEF less than 0.55 in 7 patients, by failure of LVEF to increase by 0.05 units in 13 patients, and by an increase in left ventricular end-systolic volume index (LVESVI) during exercise greater than 5% above baseline in 11 patients. Of the 26 patients with multivessel coronary artery disease, 24 had major cardiac complications. The subsequent course of these 26 patients was correctly predicted in 13 by LVEF less than or equal to 0.40, in 20 by LVEF less than 0.55, in 25 by a failure of LVEF to increase by 0.05 units during exercise, and in 20 by an increase in LVESVI by greater than 5% during exercise. Thus, submaximal exercise testing with radionuclide ventriculography may provide valuable prognostic information concerning the occurrence of major cardiac events after myocardial infarction not only in patients with multivessel disease, but also in those with single-vessel disease. Exercise-induced abnormalities of left ventricular function may have greater prognostic importance than the delineation of coronary arterial anatomy or the assessment of residual left ventricular function at rest.

Left ventricular functional alterations at rest and during submaximal exercise in patients with recent myocardial infarction

Submaximal exercise testing with radionuclide ventriculography was performed in 117 patients prior to hospital discharge 16.7 +/- 6.7 days (SD) following acute myocardial infarction. The hypothesis tested in this study was that patients with different locations and types of infarction have different functional responses to submaximal exercise prior to discharge. The distribution of the myocardial infarctions were anterior transmural in 33, inferior transmural in 39, anterior nontransmural in 23, inferior nontransmural in 19, and indeterminant in three. Patients with transmural infarction generally had significantly larger resting left ventricular volumes at end-diastole and end-systole and lower ejection fractions and systolic blood pressure/end-systolic volume indexes than patients with nontransmural infarctions (p less than 0.05). During submaximal exercise, the change in end-systolic volume was significantly different in these two groups. When patients were separated further into anterior and inferior transmural subgroups, the patients with anterior transmural infarction had significantly lower left ventricular ejection fractions and higher right ventricular ejection fractions than the group with inferior transmural infarction (p less than 0.05). In response to exercise, the group with anterior transmural infarction had a significant decrease in left ventricular ejection fraction and a blunted systolic blood pressure/left ventricular end-systolic volume index, in comparison to patients with inferior myocardial infarction (p less than 0.05); this was the only group to have a significant increase in end-systolic volume. The group variance for the parameters studied was large, particularly during exercise when the individual responses were frequently directionally opposite from the group means. The group with anterior transmural infarction was the most homogeneous, with 26 of 33 having a directionally abnormal response to submaximal exercise. It was concluded that the group with anterior transmural infarction generally displayed the most abnormal left ventricular function. However, despite significant group differences in resting ventricular function with different infarcts, the intragroup variability at rest and in response to exercise was too great to permit an accurate prediction of the subject's resting ventricular performance or to permit a prediction of exercise response based solely on location of the infarct.

Treatment of stable angina of effort with verapamil: a double-blind, placebo-controlled randomized crossover study

The effects of verapamil were assessed in 26 patients with stable exertional angina pectoris in a double-blind, placebo-controlled, randomized crossover protocol using serial treadmill tests. Verapamil, 480 mg/day, reduced anginal frequency from 5.6 +/- 7.3 to 2.2 +/- 3.9 attacks per week (p less than 0.001) and nitroglycerin consumption from 3.4 +/- 4.9 to 1.2 +/- 2.5 tablets per week (p less than 0.05) compared with placebo. Treadmill time increased from 6.4 +/- 2.1 minutes during the placebo phase to 7.5 +/- 1.8 minutes during the verapamil phase (p less than 0.001). Verapamil's beneficial effect appeared to be related, in part, to a 10% reduction of the rate-pressure product at rest (p less than 0.05) and a 12% reduction during submaximal exercise (p less than 0.001). Verapamil also caused less marked ST-segment depressions at peak exercise (p less than 0.05) at a similar rate-pressure product, suggesting a favorable redistribution of coronary blood flow to the ischemic zone. Side effects from verapamil were minimal, consisting mainly of constipation (six patients). Verapamil appears to be a safe and effective drug for treating angina of effort.

Diuretic-induced ventricular ectopic activity

The need to avoid hypokalemia during diuretic therapy in nondigitalized patients has been questioned. Twenty-one patients with (1) mild essential hypertension, (2) plasma potassium of less than 3.5 meq/liter during previous diuretic treatment, and (3) normal findings [less than 6 unifocal ventricular premature beats/hour] on 24-hour ambulatory electrocardiographic monitoring and exercise testing were treated with hydrochlorothiazide (50 mg twice a day) for four weeks and then ambulatory electrocardiographic monitoring and exercise testing were repeated. Ambulatory electrocardiographic monitoring revealed that ventricular ectopic activity developed in seven patients and complex ventricular ectopic activity (multifocal ventricular premature beats, ventricular couplets and/or ventricular tachycardia) in four. Only two of these seven had ventricular ectopic activity during exercise testing while they were hypokalemic. Potassium repletion in these seven patients with spironolactone abolished complex ventricular ectopic activity and reduced unifocal ventricular premature beats significantly (p less than 0.01) from an average of 71.2 ventricular premature beats/hour/patient during hydrochlorothiazide treatment to 5.4 ventricular premature beats/hour/patient after potassium repletion. Although complex ventricular ectopic activity was more likely to occur with plasma potassium less than 3.0 meq/liter, restoration of normokalemia was required in several patients to abolish residual ventricular ectopic activity. Persistent ventricular ectopic activity in one patient suggested that myocardial injury sustained during hypokalemia may initiate chronic ventricular ectopic activity. Even in nondigitalized patients, the hazard of diuretic-induced ventricular ectopic activity warrants correction of hypokalemia.

Submaximal exercise testing after unstable angina

Sixty-one consecutive men, mean age 56 years, who fulfilled criteria for unstable angina and who responded to medical therapy, underwent submaximal exercise testing prior to hospital discharge and at least 3 days after their last episode of angina. Forty-two patients were receiving propranolol at the time of exercise. Submaximal exercise was targeted to 120 beats/minute and strict criteria for the premature termination of each study were followed. Follow-up data were available on 55 patients post-discharge over a period of 6 to 36 weeks. No patient suffered recurrence of unstable angina or myocardial infarction due to the exercise test. Exercise was prematurely terminated by an ischemic response (chest pain and/or ST segment changes) in 34 patients (56%) and by leg fatigue in 13 patients (21%). Only five patients had exercise-induced ventricular ectopic activity, four of whom were not receiving propranolol. Nine patients achieved the target heart rate. Exercise-induced abnormal electrocardiographic changes predicted the postdischarge recurrence of episodes of unstable angina (p less than 0.05). Comparison of predischarge submaximal exercise data with postdischarge maximal exercise shows that recovery in cardiovascular function after unstable angina occurs soon after stabilization and prior to the submaximal test.

Functional evaluation of aortocoronary bypass surgery by exercise testing

Exercise stress test was performed prior to and after aortocoronary bypass surgery in 91 male patients in an attempt to quantitate the change of physical capacity after operation and to correlate this to clinical improvement and late shunt angiography. The mean maximal work load was significantly higher after than prior to surgery in all groups. In average the maximal work load increased 65%. No difference was found between patients who were operated on for stable angina pectoris and those with unstable angina or impending myocardial infarction. Patients, who subjectively were without symptoms or much better after surgery, had a higher maximal work load after operation than those who were subjectively less improved or worse. In a sub-group of patients the maximal oxygen consumption was calculated in per cent of normal values for the age. The mean maximal oxygen consumption increased from 59% prior to surgery to 76% of normal values after surgery.

Exercise testing in men with significant left main coronary disease

The exercise tests of 26 male patients with significant left main disease were compared with those of 51 patients with three-vessel disease and 38 patients with two-vessel disease. Exercise-induced ischaemia (chest pain and/or greater than 1 mm ST segment change) occurred in 100 per cent of left main, 69 per cent of three-vessel, and 45 per cent of two-vessel disease patients. Though the mean peak work load was significantly higher in the two-vessel disease group than in those with three-vessel of left main disease, there was a wide overlap between groups. No intergroup differences were found in mean peak heart rates. In patients taking propranolol, no differences in mean peak work loads and heart rates were seen. The study showed that the absence of an exercise-induced abnormal electrocardiographic response virtually excludes left main disease. As judged by exercise performance, the presence of left main disease did not correlate with the severity of the patient's symptomatology. Propranolol did not influence the frequency of an ischaemic response in patients with left main or three-vessel disease.

A new geriatric application of electrocardiographic treadmill testing in an office setting

An accepted method of measuring exercise tolerance was applied exclusively to geriatric practice for the purpose of exercise prescription. This stress testing was performed to minimize the risks of introducing exercise in an elderly population, and to restore or maintain elderly persons at their own optimal level of function, for life. As no geriatric testing protocol was available, two standardized protocols were chiefly used to start the trial program in March, 1978. A geriatric modification devised by the author is described. During the first month of the study, in a physician's office, ECG-monitored treadmill testing was conducted without mishap in 175 patients (age range, 60--89 years). All but 4 of the subjects (98 percent) led habitually sedentary lives, and documented coronary heart disease was present in about one-fourth of the series. The initial test data in this proposed continuing study are summarized. The methods for candidate selection, the safety precautions, and the test procedure are outlined. The distinction is made between testing by functional grades and testing to maximal levels. Information obtained from this stress test is an integral part of the individualized exercise prescription for each geriatric subject.

Evaluation of thallium-201 exercise scintigraphy in coronary heart disease

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Reproducibility of work performance at serial exercises in patients with angina pectoris

The reproducibility of serial upright exercises in patients with ischaemic heart disease was tested. Five short term exercises (4--8 min) with continuous load increase and with 30 min rest intervals between tests were used. No tendency to change was found concerning work time to appearance of angina (APT), maximal working time (MWT) or time for disappearance of angina after exercise (DPT). The coefficient of variation was low for APT and MWT but considerably higher for DPT, being 9, 5 and 27%, respectively. MWT was considered as the end-point of choice. The ST depression at MWT showed no tendency to change and the variation was moderate (14%), while at APT and DPT the variation was high (52%), but, likewise, with no tendency to change. The maximal heart rate increased slightly and significantly (P less than 0.001), while the maximal blood pressure was constant throughout tests, thus the maximal rate pressure product tended to increase. This indicates a slight improvement of the myocardial performance at serial exercises, which, however, does not affect the reproducibility of the anginal reaction.

Exercise testing for detection of myocardial ischemia in patients with abnormal electrocardiograms at rest

This review consists of two parts: (1) discussion of the electrophysiologic mechanisms that are believed to produce ventricular repolarization changes during the electrocardiographic stress test, and (2) clinical assessment of the electrocardiographic changes with stress in patients with an abnormal electrocardiogram at rest. In the first part, the mechanisms of S-T segment elevation, S-T segment depression, T wave changes and linked S-T and T wave changes are reviewed. In the second part, all electrocardiographic abnormalities at rest are grouped into four categories: (1) changes that mask the manifestations of ischemia, (2) changes that stimulate or exaggerate the manifestations of ischemia, (3) changes that have no important effect on the manifestations of ischemia, and (4) changes that reproduce the patterns of acute myocardial infarction after an apparent healing. The reported studies of electrocardiographic stress testing in patients who have abnormal electrocardiogram at rest are summarized.

Effects of digitalis on the exercise electrocardiogram in normal adult subjects

Controversy continues regarding the effects of administration of digitalis upon the exercise electrocardiogram. Thus, maximal treadmill exercise tests were performed before and two weeks after administration of 0.25 mg of digoxin daily in 15 normal subjects (documented by cardiac catheterization and coronary arteriographic studies). Administration of digitalis induced abnormal findings on exercise tests in all 14 subjects with serum levels of digoxin greater than or equal to 0.5 ng/ml; however, at workloads greater than 75 to 90 percent of maximal predicted heart rate, the changes in the ST segment reverted to a normal configuration in all subjects, thereby providing differentiation of digitalis-induced ST-segment alterations from those due to myocardial ischemia at maximal treadmill stress.

Electrocardiographic exercise test in patients with abnormal T waves at rest

The results of submaximal ECG exercise test were evaluated in six leads recorded simultaneously in two groups of patients with T-wave abnormalities in one or more of Leads I, II, and V4-6. Group I included 185 patients with documented ischemic heart disease (IHD) and Group II 28 patients in whom IHD appeared unlikely. The test was positive in 88 per cent of patients in Group I and in 4 per cent of patients in Group II. In the majority of patients in both groups the T wave either did not change or became more positive or less negative after exercise. The pattern of exercise-induced T-wave changes was similar in patients with and without IHD, and was influenced predominantly by the physiologic effects of exercise. T-wave normalization after exercise occurred frequently in patients with and without IHD, and in patients with positive and negative exercise tests. Our results suggest that T-wave abnormalities, not caused by hypertrophy, conduction disturbances, drugs, or electrolyte imbalance, do not modify the results of submaximal ECG stress test, and that behavior of T wave after exercise does not alter the interpretation of the postexercise ECG. The independent behavior of the S-T segment and T wave after exercise in consistent with the theory that the S-T segment and the T wave are generated by different components of the ventricular action potential.

Exertional hypotension and postexertional ventricular fibrillation in stress testing

Six men, clinically diagnosed as having coronary heart disease, had postexertional ventricular fibrillation after maximal exercise testing. The common featureof their treadmill performance was "exertional hypotension," that is, a decrease or a limited increase (10 mm Hg) in systolic blood pressure. All six men were successfully resuscitated with electircal defibrillation. The major indication for electrocardiographic monitoring is the detection of major ventricular arrhythmias and changes in QRS-ST-T of acute myocardial infarction or severe ischemia, all of which are urgent indications for stopping exertion. Close supervision both during and after exercise testing is essential, particularly in men with severe coronary artery disease; monitoring of changes in systolic pressure during and shortly after exercise testing is as important as searching for changes in the -S-T segment.

New approaches to resolving diagnostic problems in patients with angina pectoris

Several new noninvasive techniques are now available to evaluate the patient with chest pain to determine if myocardial ischemia is present. Continuous ambulatory ECG monitoring can detect myocardial ischemia in some patients who have normal ECG responses to graded exercise tests. Defects in myocardial perfusion can be visualized by radionuclide imaging at rest and after exercise. Also, abnormal left ventricular wall motion due to myocardial ischemia can be detected by gated blood pool scanning at the same time. Other techniques can olso be valuable in evaluating wall motion. Standard M-mode echocardiography can detect anteroseptal and posteroinferior wall motion abnormalities with remarkable anatomic detail, and newer echo techniques are promising for delineating the motion of other parts of the left ventricle. Finally, abnormal contractile areas can be assessed by videotracking the fluoroscopic cardiac silhouette and by a new noninvasive technique, the displacement cardiograph, which does not involve radiation exposure. Although none of these tests are both highly sensitive and highly specific for myocardial ischemia, their combined application in a symptomatic patient may provide considerable useful information which will help to determine who should be subjected to the risk and expense of coronary arteriography.

Multifactor evaluation of the determinants of ischemic electrocardiographic response to maximal treadmill testing in coronary disease

Despite widespread use of treadmill stress in the detection of coronary disease, detailed information relating the important features of coronary pathoanatomy to the ischemic response noted on the electrocardiogram is lacking. Accordingly, 91 consecutive patients undergoing graded maximal exercise tests (MEXT) who were found to have clinical stenosis (larger than or equal to 75 per cent luminal narrowing) of at least one of the three major coronary arteries on coronary arteriography were evaluated. Positive MEXT was defined as larger than or equal to 0.1 mV horizontal or downsloping S-T segment depression larger than or equal to 0.08 second beyond J point. Over-all sensitivity of positive MEXT was 59 of 91 (65 per cent) patients; 11 of 26 (42 per cent) with single vessel stenosis, 20 of 30 (66 per cent) with two vessel disease and 28 of 35 (80 per cent) with three vessel disease. In patients with two vessel disease, the frequency (p less than 0.05) of positive MEXT was greater in those with (15 of 21;71 per cent) than in those without (five of nine; 55 per cent) stenosis of the left anterior descending artery. Concerning the site of intravessel stenosis, the frequency of positive MEXT was greater (p less than 0.05) with stenosis proximal to the left anterior descending artery in patients with one vessel disease. Quantification of total numbers of intra- and intervessel stenoses revealed 2.7 stenoses in the 59 patients with positive MEXT in contrast (p less than 0.01) to 1.9 in 32 patients with negative MEXT. Similarly, graded luminal narrowing index of severity of total stenoses per patient was 9.9 in those with positive MEXT compared (p less than 0.01) to 6.1 in those with negative MEXT. The poststenotic myocardial perfusion index, estimated by graded distal vessel opacification per major vessel disease, was only 1.5 in those with positive MEXT contrasted (p less than 0.01) to 2.4 in those with negative MEXT. These data indicate that sensitivity of positive MEXT in patients with coronary disease is most closely determined by the number of major coronary vessels involved, the total number of major vessels stenosed, the severity of total stenoses and poststenotic distal vessel perfusion. Less important factors are the precise site of intravessesl stenosis and the specific major coronary artery involved, although stenosis proximal to the left anterior descending artery favored positive MEXT. Unimportant variables were the quality of collateral vessels, ventricular function and prior inferior infarction. Angina occurred more frequently in those with positive MEXT, and marked degree of positive MEXT indicated stenosis proximal to the left anterior descending artery.

Maximal exercise stress testing in normal and hyperlipidemic children

Electrocardiographic and cardiovascular responses during maximal exercise were evaluated in 103 normal children and in 82 children with familial hyperlipoproteinemia. The normal and hyperlipidemic children were comparable in regards to age, weight--height index, resting and exercise blood pressures, and maximal working capacity indices. The cohort of 82 hyperlipidemic children included 61 children (29 boys and 32 girls) with well defined "monogenic" familial hyperlipoproteinemia. Segmental ST depression on the exercise electrocardiogram occurred in 8 of these 29 boys (27.6%) as compared to 4 of 55 normal boys (7.3%), P less than 0.025 and in 6 of the 32 girls (19%) as compared to 7 of 48 normal girls (14.6%), P greater than 0.1. Segmental ST depression was present in 14 of 61 (23%) children with "monogenic" hyperlipoproteinemia, as compared to 11 of 103 (10.75%) normal (x2 = 4.47, P less than 0.05). An assessment of the clinical significance of an abnormal exercise electrocardiogram in male children with "monogenic" hyperlipoproteinemia must await the following: (1) two to four decades of observation and study of the development of morbid or mortal coronary disease, or (2) the future development of improved invasive or noninvasive techniques for the early detection of covert coronary occlusive disease. Currently, maximal exercise electrocardiography cannot be contemplated as a useful indicator of eventual premature coronary artery disease in asymptomatic hyperlipidemic children.