Multistage electrocardiographic exercise tests. Principles and clinical applications

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.

The provocative test and their diagnostic value in sinus node failure

Exercise and pharmacologic tests were used for evaluation of the sinus node and S-A function. In all 10 normal persons, the heart rate raised above 90/min without development of cardiac arrhythmia. Among 13 patients with sinus node failure, only 1 had the heart rate raised to 90/min after exercise test and 7 above 90/min after medicinal induction. Cardiac arrhythmia, which is characteristic in sinus node failure, may appear during the test, provide an important clue in making a diagnosis. Criteria for the provocative tests are described. During the test, it is necessary to be on guard against any untoward effects. The patients in this study have been all uneventful throughout.

Treadmill exercise testing of mass screening for coronary risk factors

The prevalence of an abnormal maximal treadmill stress test (MTST) was correlated with coronary risk factors in 1,077 asymptomatic adults (709 men and 368 women) in Long Beach, California. Of 1,077 adults, 113 (10.5%) had a positive MTST. A positive MTST was correlated with sex (p less than 0.001), age (p less than 0.001), a serum cholesterol less than or equal to 200 mg% (p less than 0.02), hypertriglyceridemia (p less than 0.05), cigarette smoking (p less than 0.025), and with the number of coronary risk factors (p less than 0.005) but not with hypertension, cigar or pipe smoking, obesity, or blood sugar.

Oral nitroglycerin as a prophylactic antianginal drug: clinical, physiologic, and statistical evidence of efficacy based on a three-phase experimental design

With the use of a three-phase experimental design, the efficacy of oral nitroglycerin has been evaluated in a total of 53 patients with documented angina pectoris due to coronary artery disease. The study were a double-blind, randomized, and cross-over comparison of controlled-release nitroglycerin (2.6 mg. tablets administered three times daily) and an indistinguishable placebo. Sixteen patients recorded anginal symptoms by the diary method over a 6 month trial of randomly sequenced 1 month periods of drug or placebo. In 15 patients, ST segments were monitored with a Holter dynamic electrocardiograph for periods of 10 to 12 hours under normal life style and evaluated by matching activities during periods of drug and placebo. In 22 patients, a multistage treadmill exercise test was conducted to an endpoint of anginal pain. The three phases of the investigation were run in succession; each phase was completed before the next one was begun. Oral nitroglycerin reduced the incidence and severity of anginal attacks by 47.2 and 49.4 per cent, respectively, and decreased the number of sublingual nitroglycerin tablets used by 51.1 per cent in comparison to placebo (p less than 0.001). Eleven of 16 patients (69 per cent) decreased their need for sublingual nitroglycerin by over 50 per cent. Based on a polynomial trend analysis over a period of 8 weeks, no tolerance to the therapeutic effects of the drug was found. With DCG monitoring, drug decreased the ST segment depression from 1.76 mm. on placebo to 1.12 mm, with a significant difference of 0.64 mm. (p less than 0.001). ST segment depression was decreased more than 0.5 mm. by drug in comparison to placebo in 10 of 15 patients (66 per cent). Larger depressions of the ST segment noted with placebo at heart rates greater than 80 beats per minute were prevented by administration of the drug. During treadmill exercise, drug delayed the onset of pain by 83 seconds (64 per cent) over placebo (p less than 0.001) and decreased the duration of pain by 70 seconds (49 per cent) in comparison to placebo (p less than 0.001). Drug did not affect heart rate or systolic blood pressure at rest or after exercise, as well as rate-pressure product for production of angina following exercise (p less than 0.05). There was no side effects reported caused by the drug. The data demonstrate that oral nitroglycerin, given as controlled-release tablets, was absorbed from the gastrointestinal tract in quantities sufficient to provide statistically significant clinical improvement of angina pectoris.

Maximum treadmill exercise electrocardiography in female patients

Exercise testing has become standardized for the diagnostic and functional evaluation of male patients but little data is available regarding its specificity and sensitivity in the female. Therefore, maximum treadmill exercise (Bruce protocol) was performed on 98 consecutive females and compared to coronary arteriography. Using 50% obstruction as indicating coronary artery disease and 1 mm ST-segment depression (horizontal or downsloping) as positive for ischemia, 24 patients had coronary artery disease with seven false-negative results (sensitivity = 71%) and 74 patients had no coronary artery disease with 16 false-positive responses (specificity = 78%).

Five of seven false-negative tests were in patients with single-vessel disease. Eleven of 16 false-positive responses were in patients on digitalis, diazepam, or methyldopa. In 39 patients on no drug therapy except for nitroglycerin there were no false negatives and only four false-positive tests. There were no false negatives and only two false-positive tests in 34 patients with normal resting electrocardiograms. Only one of 18 patients with both normal resting electrocardiograms and on no drug therapy had a false-positive test result. Eleven false-positive and seven false-negative results occurred in 40 patients with both an abnormal resting electrocardiogram and associated drug therapy.

The exercise electrocardiographic response in female patients is similar to the male when patients with resting electrocardiographic abnormalities and concomitant drug therapy are eliminated.

Maximum treadmill exercise test in patients with abnormal control electrocardiograms

To determine the validity and safety of exercise induced ST changes (1 mm ischemic depression or further depression in ECG lead V 5 ) as an indication of coronary artery disease (CAD) in patients with abnormal control electrocardiograms (ECG), 121 such patients were compared to 57 patients with a normal control ECG. All underwent a maximum graded treadmill exercise test and coronary arteriography. Among those patients with normal control ECGs, there were no false positives and five false negatives (sensitivity-85%, specificity-100%). In 61 patients with abnormal ECG (no drug therapy except nitrates) there were four false positives and nine false negatives (sensitivity-76%, specificity-79%). In this group of patients T waves reverted from negative to positive in four patients with CAD and 10 patients with no CAD, but T inversion during exercise only occurred in those with CAD (6 patients). Three of 12 patients (25%) with ECG evidence of old infarction and four of eight with single vessel disease had false negative tests. In 60 patients with abnormal ECG on drug therapy there were 10 false positives (17%) and 15 false negatives (sensitivity-55%, specificity-63%). Not helpful in differentiation were resting T vs ST changes, induction of arrhythmias or exercise induced chest pain.

The validity of exercise induced ST changes in differentiating CAD is excellent when the control ECG is normal and is only slightly reduced with control ST-T wave abnormalities. When the latter occur in association with cardiovascular drug therapy, other than nitrates, the exercise ECG is of no use in differential diagnosis although still valid and safe for the determination of exercise tolerance.

Diagnosis of obstructive coronary disease by maximal exercise and atrial pacing

The reliability of graded maximal exercise treadmill testing and right atrial pacing in diagnosing significant obstructive coronary artery disease was evaluated in 74 consecutive patients referred to a cardiac unit with chest pain consistent with angina pectoris. The results of maximal exercise testing and right atrial pacing, with regard to the presence or absence of the patient's characteristic chest pain or discomfort and ischemic ST segment depression, were compared with the findings determined by selective coronary arteriography. Ischemic ST segment depression was defined as a downward displacement of one full mm or more of a horizontal or downward sagging ST segment.

Forty-nine of the 74 patients studied were found to have significant coronary arteriographic obstruction, i.e., greater than 75% obstruction of one major coronary artery. The occurrence of the patient's characteristic chest pain or discomfort during maximal exercise testing or right atrial pacing is an excellent indicator of the presence of obstructive coronary artery disease, since all of the 41 patients developing their characteristic pain on maximal exercise testing had coronary arteriograms positive for obstructive coronary disease (no false positives), and 46 of 47 patients with characteristic chest pain on right atrial pacing had selective coronary arteriograms positive for obstructive coronary disease. When present, one mm ST depression during maximal exercise treadmill testing also reliably indicates arteriographic obstructive coronary disease (26 of 27 patients). However, the presence or absence of ischemic ST depression during right atrial pacing is a particularly unreliable indication of the presence or absence of arteriographic obstructive coronary disease: 15 of 25 false positive tests, and 13 of 49 false negative tests.

Inability of the submaximal treadmill stress test to predict the location of coronary disease

Two hundred patients had submaximal treadmill stress tests (STSTs) and selective coronary arteriography performed within 2 months of each other. An attempt was made to assess the predictability of disease isolated to any given coronary vessel by performance on the treadmill. This was not possible for disease isolated to the right coronary, the left anterior descending, the circumflex branch of the left coronary, or a combination of right coronary and circumflex arteries. Eleven patients had disease in the left main coronary artery; all had associated disease of some other branch as well. One of these patients had a negative submaximal treadmill stress test but was unable to reach 90% of his maximum predicted heart rate. The remaining 10 patients had positive STSTs. Patients with 26-50% narrowing of any branch had treadmill results similar to those with 51-75% narrowing. There was a large number of patients with single-vessel disease in the study and most of the negative STSTs occurred in this group. Nevertheless, within this group no one vessel gave a higher incidence of positive STSTs than any other. It is concluded that (1) a positive STST is more likely to be associated with increased severity and extent of coronary artery disease; (2) a negative STST is more likely to be found in disease limited to a single vessel; and (3) within the latter group, the STST is of no value in predicting the specific coronary artery involved.

Maximal treadmill exercise electrocardiography. Correlations with coronary arteriography and cardiac hemodynamics

Electrocardiograms were recorded during and at 2-min intervals following maximal treadmill exercise in 100 patients and were correlated with coronary arteriograms, left ventricular cineangiograms, and resting and exercise cardiac hemodynamics. The incidence and extent of exercise-induced "ischemic" S-T segment depression increased significantly ( P < 0.01) with increasing extent of coronary artery disease (CAD). A criterion of abnormality of 1.0 mm or greater S-T depression most accurately predicted the presence of CAD with a specificity (true negative) of 89% and a sensitivity (true positive) of 62%. Criteria of ≧0.75 and ≧0.5 mm S-T depression offered improved sensitivities (68 and 84%, respectively) but markedly reduced specificities (78 and 57%, respectively).

A significant correlation ( P < 0.005) was found between increasing extent of exercise-induced S-T segment depression and the pulmonary artery wedge pressure during exercise. There were no correlations between the presence or extent of exercise-induced S-T depression and the resting or exercise pulmonary artery pressure, cardiac index, stroke-volume index, or exercise factor, or the resting left ventricular dp/dt, left ventricular end-diastolic pressure, left ventricular ejection fraction, or presence of asynergy on the left ventricular cineangiogram.

The maximal treadmill exercise test provided a noninvasive method for predicting the presence and extent of significant CAD in the individual patient with chest pain. Although a normal treadmill exercise test provided little insight into the underlying resting and exercise hemodynamics, an abnormal treadmill test (≧1.0 mm S-T depression) was associated with an abnormal increase in left ventricular filling pressure with exercise in 90% of the patients.