Assessment of the myocardial perfusion pattern in patients with multivessel coronary artery disease

Ticagrelor for Secondary Prevention of Atherothrombotic Events in Patients With Multivessel Coronary Disease

BACKGROUND

Patients with prior myocardial infarction (MI) and multivessel coronary disease (MVD) are at high risk for recurrent coronary events.

OBJECTIVES

The authors investigated the efficacy and safety of ticagrelor versus placebo in patients with MVD in the PEGASUS-TIMI 54 (Prevention of Cardiovascular Events in Patients With Prior Heart Attack Using Ticagrelor Compared to Placebo on a Background of Aspirin-Thrombolysis In Myocardial Infarction 54) trial.

METHODS

Patients with a history of MI 1 to 3 years before inclusion in the PEGASUS-TIMI 54 trial were stratified in a pre-specified analysis based on the presence of MVD. The effect of ticagrelor (60 mg and 90 mg) on the composite of cardiovascular death, MI, or stroke (major adverse cardiovascular events [MACE]), as well as the composite of coronary death, MI, or stent thrombosis (coronary events), and on TIMI major bleeding, intracranial hemorrhage (ICH), and fatal bleeding were evaluated over a median of 33 months.

RESULTS

A total of 12,558 patients (59.4%) had MVD. In the placebo arm, compared with patients without MVD, those with MVD were at higher risk for MACE (9.37% vs. 8.57%, adjusted hazard ratio [HR_adj]: 1.24; p = 0.026) and for coronary events (7.67% vs. 5.34%, HR_adj: 1.49; p = 0.0005). In patients with MVD, ticagrelor reduced the risk of MACE (7.94% vs. 9.37%, HR: 0.82; p = 0.004) and coronary events (6.02% vs. 7.67%, HR: 0.76; p < 0.0001), including a 36% reduction in coronary death (HR: 0.64; 95% confidence interval: 0.48 to 0.85; p = 0.002). In this subgroup, ticagrelor increased the risk of TIMI major bleeding (2.52% vs. 1.08%, HR: 2.67; p < 0.0001), but not ICH or fatal bleeds.

CONCLUSIONS

Patients with prior MI and MVD are at increased risk of MACE and coronary events, and experience substantial relative and absolute risk reductions in both outcomes with long-term ticagrelor treatment relative to those without MVD. Ticagrelor increases the risk of TIMI major bleeding, but not ICH or fatal bleeding. For patients with prior MI and MVD, ticagrelor is an effective option for long-term antiplatelet therapy. (Prevention of Cardiovascular Events [e.g., Death From Heart or Vascular Disease, Heart Attack, or Stroke] in Patients With Prior Heart Attack Using Ticagrelor Compared to Placebo on a Background of Aspirin [PEGASUS]; NCT01225562).

[Clinical predictors of the presence of perfusion defects in more than than one territory in myocardial scintigraphy with GATED-SPECT]

BACKGROUND AND OBJECTIVE

Extension of perfusion defects is associated with outcome in patients undergoing myocardial scintigraphy. The study aimed to identify the clinical characteristics that can predict the existence of perfusion defects in more than one territory in patients referred for myocardial scintigraphy with GATED-SPECT.

PATIENTS AND METHODS

A total of 193 patients undergoing myocardial scintigraphy with GATED-SPECT (99mTc-tetrofosmine) were studied. Clinical variables and scintigraphy results were studied to determine what clinical variables are associated with perfusion defects in more than one territory.

RESULTS

The number of territories with perfusion defects per patient was 1.1 0.8 and 29% had perfusion defects in > 1 territory. Patients with greater probability of having perfusion defects in > 1 territory were those with previous myocardial infarction (44% vs 21%, p = 0.030) and males (33% vs 10%, p = 0.006). In addition, patients with > 2 coronary risk factors had a statistical tendency to have defects in > 1 territory (47% vs 20%, p = 0.057). Only 15% of the patients with one of these three characteristics had perfusion defects in > 1 territory in comparison with 45% and 83% in those with 2 or 3 factors, respectively.

CONCLUSION

Considering 3 simple clinical characteristics (male gender, previous infarction and existence of > 2 coronary risk factors), it is possible to predict which patients are more likely to show perfusion defects in > 1 territory during GATED-SPECT myocardial scintigraphy.

Prognostic implications of normal exercise tomographic thallium images in patients with angiographic evidence of significant coronary artery disease

This study examines the prognostic implications of normal exercise tomographic thallium images in medically treated patients with angiographic evidence of coronary artery disease (CAD). There were 97 patients aged 60 +/- 10 years; 52 had 1-, 30 had 2-, and 15 had 3-vessel CAD (> or = 50% diameter stenosis). The exercise test was submaximal in 51 patients (53%); ST-segment depression during exercise occurred in 20 patients (21%), and angina during exercise occurred in 23 patients (24%). Most patients (71%) were receiving antianginal therapy. During a mean follow-up of 32 months, only 3 patients had cardiac events: 2 died of cardiac causes and 1 had nonfatal myocardial infarction (event rate 1.1%/year). None of those 3 patients had positive ST response during exercise. Thus, medically treated patients with CAD (including those with multivessel CAD) have a benign prognosis in the presence of normal exercise thallium images. These results have important implications in patient management and cost of health delivery.

Independent and incremental prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging in coronary artery disease

OBJECTIVES

The objective of this study was to examine the independent and incremental prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging in patients with angiographically defined coronary artery disease.

BACKGROUND

Previous studies showed the importance of exercise thallium-201 in risk stratification. However, most of these studies used planar imaging techniques.

METHODS

Follow-up data were obtained in 316 medically treated patients with coronary artery disease. Cox proportional hazards regression models were used to examine the independent and incremental prognostic values of clinical, exercise, thallium and cardiac catheterization data.

RESULTS

There were 35 events (cardiac death or nonfatal myocardial infarction) at a mean follow-up time of 28 months. Univariate analysis showed that gender (chi-square = 5.1), exercise work load (chi-square = 3.1), extent of coronary artery disease and left ventricular ejection fraction (chi-square = 14.8) and thallium variables (chi-square = 22.7) were prognostically important. The thallium data provided incremental prognostic value to catheterization data (chi-square = 33.7, p < 0.01). The extent of the perfusion abnormality was the single best predictor of prognosis (chi-square = 14). Patients with a large perfusion abnormality had a worse prognosis than that of patients with a mild or no abnormality (Mantel-Cox statistics = 10.6, p < 0.001).

CONCLUSIONS

In medically treated patients with coronary artery disease, exercise SPECT thallium imaging provides independent and incremental prognostic information even when catheterization data are available. The extent of the perfusion abnormality is the single most important prognostic predictor.

Identification of high-risk patients with left main and three-vessel coronary artery disease by adenosine-single photon emission computed tomographic thallium imaging

The purpose of this study was to examine the ability of SPECT imaging with thallium-201 during adenosine-induced coronary hyperemia to detect high-risk patients with left main or three-vessel CAD. There were 339 patients: 102 with either left main or three-vessel CAD (group 1) and 237 with no CAD, one-, or two-vessel disease (group 2). By means of univariate analysis, several variables were found to differ between groups 1 and 2: Q wave myocardial infarction (35% vs 25%, p < 0.05), ST segment depression (35% vs 19%, p < 0.001), age (67 +/- 9 vs 62 +/- 10 years, p < 0.001), resting systolic blood pressure (142 +/- 22 vs 135 +/- 20 mm Hg, p < 0.01), abnormal thallium images (95% vs 74%, p < 0.0001), multivessel thallium abnormality (76% vs 39%, p < 0.0001), extent of thallium abnormality (24 +/- 11% vs 19 +/- 13%, p < 0.0001), and increased lung thallium uptake (39% vs 15%, p < 0.01). According to stepwise discriminant analysis, only three variables were predictors of high risk: multivessel thallium abnormality (chi 2 = 27), increased lung thallium uptake (chi 2 = 10), and ST depression (chi 2 = 5). On the basis of these variables, patients were divided into three groups with different prevalence rates for left main and three-vessel CAD: 63% in 68 patients, 30% in 137 patients, and 13% in 137 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of high-risk patients with left main and three-vessel coronary artery disease using stepwise discriminant analysis of clinical, exercise, and tomographic thallium data

This large-scale study examined the ability of stepwise discriminant analysis of clinical, exercise, and thallium tomographic data to detect high-risk patients with three-vessel or left main disease. There were 834 patients, 229 with three-vessel or left main disease (group 1) and 605 (group 2) with either two-vessel disease (n = 236), one-vessel disease (n = 195), or no coronary artery disease (n = 174). The two groups were different in age, exercise heart rate, ST segment depression during exercise, exercise systolic blood pressure, abnormal thallium scans, reversible perfusion defects, extent of thallium abnormality, number of vascular territories with perfusion abnormalities, left ventricular cavity dilatation, and increased lung thallium uptake. On multivariate stepwise discriminant analysis, only three variables were independent predictors of high risk. These included multivessel thallium abnormality (F = 107, p < 0.001), exercise heart rate (F = 27, p < 0.001), and ST segment depression (F = 8, p < 0.01). Based on these three variables, patients could be stratified into three categories with different prevalences of left main or three-vessel disease; the prevalence was 53% in 239 patients, 24% in 271 patients, and 12% in 324 patients. Thus high-risk patients with left main or three-vessel disease can be identified by exercise thallium tomographic imaging that uses a model based on stepwise discriminant analysis. The thallium data are far more powerful than the clinical or treadmill exercise data.

The treadmill exercise score revisited: coronary arteriographic and thallium perfusion correlates

The treadmill exercise score has been used to stratify patients into low-, moderate-, and high-risk groups. This score is derived from ST segment depression, angina, and exercise duration. To determine the coronary arteriographic and exercise thallium perfusion correlates of the score, we examined the extent of coronary artery disease and exercise single photon emission computed thallium-201 results in 834 patients for whom cardiac catheterization data were available. Of those, 174 had no coronary artery disease, 195 had one-vessel, 246 had two-vessel, and 219 had three-vessel disease. Based on the treadmill exercise score, 369 were in the low-risk, 384 in the moderate-risk, and 81 in the high-risk group. The extent of coronary artery disease was 2.1 +/- 1 diseased vessels in the high-risk, 1.7 +/- 1 in the moderate, and 1.4 +/- 1.1 in the low-risk group (p < 0.01). The extent of the thallium abnormality (maximum number of abnormal segments 120/patient) was 10 +/- 6 in the high-risk, 7 +/- 6 in the moderate, and 6 +/- 5 in the low-risk group (p < 0.05). Based on the extent of coronary artery disease and results of thallium imaging, patients were reclassified into three groups: group 1 had three-vessel disease and/or > or = 10 abnormal segments (n = 387), group 3 had no coronary artery disease or one-vessel disease and less than five abnormal segments (n = 212), and the remaining patients were in group 2 (n = 235).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of daily high-intensity exercise on myocardial perfusion in angina pectoris

Forty male patients with chronic stable angina pectoris and no prior myocardial infarction were studied by planar thallium scintigraphy with use of circumferential profile analysis. Ischemic defects were assessed by measuring degrees of circumference involved and area of defect. Data were collected for 3 vascular regions in each of 3 views (anterior, 45 degrees and 65 degrees left anterior oblique projection). Patients were then randomized to exercise and control groups, the former training for a period of 1 year using the Canadian Airforce plan for physical fitness. After 1 year, both groups were restudied. Exercise training produced a 34% reduction in degrees of ischemia overall (p less than 0.02), the most significant change being seen on the anterior view (72 degrees +/- 59 degrees before vs 30 degrees +/- 35 degrees after training). Regional analysis showed markedly improved perfusion anterolaterally and apically on the anterior view and anteroseptally on the 65 degrees left anterior oblique view. These improvements support the hypothesis that exercise training improves myocardial perfusion by enhanced collateral function.

Mechanism of abnormal postexercise systolic blood pressure response and its diagnostic value in patients with coronary artery disease

To define the factors that affect an abnormal postexercise systolic blood pressure (SBP) response and to verify the diagnostic value of that response in patients with coronary artery disease (CAD), we studied 33 normal subjects, eight patients with hypertension who had no CAD, and 42 patients with documented CAD who underwent supine leg exercise testing. SBP recovery ratios were derived by dividing the values obtained 1 and 3 minutes after exercise by the peak value. The upper normal limit of the SBP ratio was defined by two standard deviations from the mean for 33 normal subjects. The specificity of this criterion for identifying patients with CAD was 97% and the sensitivity was 60%. None of the eight patients with hypertension showed an abnormal postexercise SBP response. At peak exercise the pulmonary artery wedge pressure was significantly greater in the patients with CAD having an abnormal response. In multiple regression analysis the exercise pulmonary artery wedge pressure, the exercise SBP, and the systemic vascular resistance after exercise were determining factors for an abnormal SBP response. Three-vessel disease was more common in patients with an abnormal response. Results of this study indicate that an abnormal postexercise SBP response appears to be determined by (1) the extent of exercise-induced impairment of left ventricular function and (2) peripheral vascular tone during recovery. This study also suggests that this criterion can increase the specificity of supine exercise testing in patients with CAD including those with hypertension and might provide a marker for the severity of impaired left ventricular function by exercise in CAD.

Exercise thallium-201 scintigraphy in the localization of myocardial ischaemia

We performed a retrospective study in order to study the ability of thallium-201 exercise scintigraphy to detect and to localize coronary artery perfusion defects (in comparison with a recent coronary angiogram). We studied 81 patients (67 males); their average age was 52.3 years (men 50.5 and women 54.1 years). They performed a pulse-conducted cycle exercise test, and 2 min before end of exercise 75 MBq of thallium-201 was infused intravenously, and tomographic images were reconstructed by using a Siemens-Rota SPECT gamma camera immediately and 4 h after exercise. The thallium-201 uptake defects were attributed to different coronary arteries, and the results were compared with a coronary angiogram made afterwards in 48 patients. The groups of one-, two- and three-vessel disease were 27, 21, and 21 patients, and only 12 patients did not have significant (over 50%) stenoses. The latter had the highest ejection fraction and working capacity. Sensitivity of thallium-201 exercise scintigraphy was 65%, whereas that of exercise ECG was 41% in patients with a low ejection fraction, while in the whole material the sensitivity of thallium-201 scintigraphy was 91% and that of exercise ECG was 54%. A stenosis in the right coronary artery was best localized by the thallium-201 scintigram (86% correctly); a stenosis in the left anterior descending artery was localized correctly in 75% of the cases, but a stenosis in left circumflex artery was localized correctly only in 44%. We conclude that exercise thallium-201 scintigraphy is a useful method not only in detecting but also in localizing coronary artery disease.

Accuracy of cardiac output measured by continuous wave Doppler echocardiography during dynamic exercise testing in the supine position in patients with coronary artery disease

To estimate the accuracy of cardiac output measured by continuous wave Doppler echocardiography from the suprasternal notch and the utility of this method for evaluating left ventricular function during dynamic exercise, simultaneous thermodilution and Doppler cardiac output were measured in 34 patients with coronary artery disease during multistage ergometer exercise in the supine position. Cardiac output was measured at rest and during each stage of exercise. Twenty-five of the 34 patients whose thermodilution curves were adequate for analysis were studied during exercise. The correlation coefficient for the two methods was 0.85 at rest and 0.84 during exercise. Differences between the two methods were not significant at rest but were significant during exercise, with the thermodilution method giving the higher values. Underestimation by the Doppler method is probably due to technical problems and changes in aortic diameter during exercise. The 25 patients were classified into two groups according to pulmonary artery wedge pressure at peak exercise. There were 11 patients in Group 1 pressure (greater than or equal to 20 mm Hg at peak exercise) and 14 in Group 2 pressure (less than 20 mm Hg at peak exercise). There were significant differences in the change in cardiac index and in peak aortic velocity from rest to peak exercise between the two groups. A significant linear correlation between the percent change in peak aortic velocity and in pulmonary artery wedge pressure from rest to peak exercise was observed (r = -0.66, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of bisoprolol on cardiac performance in coronary heart disease

The effects of 5 and 10 mg bisoprolol once daily for 7 days on exercise ECG, myocardial perfusion and left ventricular function in 25 patients with stable coronary heart disease have been assessed in a double-blind, randomized, parallel group trial design. ST-segment depression during exercise was reduced by 56% by 5 mg bisoprolol and by 64% after 10 mg; the difference between the dose levels was significant. Heart rate, systolic and diastolic blood pressure and the rate-pressure product were reduced to similar extent both at rest and during exercise by both doses. Left ventricular thallium-201 scintigrams indicated a significant reduction in myocardial perfusion defects after 10 mg bisoprolol compared to baseline; however, the difference between the two active treatments was not significant. Left atrial and left ventricular diameters obtained by one-dimensional echocardiography, and the calculated shortening fraction, remained unchanged after bisoprolol, and so gave no evidence of a negative inotropic action. It is concluded that 5 mg bisoprolol was effective in once-a-day treatment of angina pectoris due to coronary heart disease, and a further improvement can be expected on increasing the dose to 10 mg.

Relation of coronary artery stenosis and pressure gradient to exercise-induced ischemia before and after coronary angioplasty

The purpose of this investigation was to evaluate the relation of coronary artery stenosis and associated pressure gradient to the magnitude of exercise-induced left ventricular dysfunction in patients with single vessel coronary artery disease. The percent stenosis and minimal cross-sectional area were measured before and after percutaneous transluminal coronary angioplasty and compared with radionuclide measurements of left ventricular function before and after angioplasty in 41 patients with proximal left anterior descending coronary artery lesions, providing 82 points of comparison. The gradient could be measured for 75 comparisons. Forty stenoses less than 50% were associated with a mean left ventricular exercise ejection fraction of 0.66 +/- 0.08 (mean +/- SD), 25 stenoses from 50 to 75% with a mean ejection fraction of 0.59 +/- 0.12 and 17 stenoses greater than 75% with a mean ejection fraction of 0.49 +/- 0.08. Thirty-five stenoses with a gradient less than 20 mm Hg were associated with a mean ejection fraction of 0.65 +/- 0.09, 24 with a gradient from 20 to 50 mm Hg with a mean ejection fraction of 0.58 +/- 0.13 and 16 with a gradient greater than 50 mm Hg with a mean ejection fraction of 0.53 +/- 0.10. These data document a relation between the magnitude of coronary artery stenosis and associated gradient to exercise-induced left ventricular dysfunction in homogeneous patient groups. However, discordance of these variables occurs commonly in individual patients.

Determinants of abnormal blood pressure response to exercise in coronary artery disease

This study assessed the determinants of exercise-induced abnormal systolic blood pressure (BP) response in 127 patients with documented coronary artery disease (CAD) who underwent exercise thallium-201 scintigraphy. Three types of systolic BP response to exercise were identified: an increase by more than 20 mm Hg (group I, n = 74); an increase by 20 mm Hg or less (group II, n = 36); and a decrease of at least 10 mm Hg (group III, n = 17). The 3 groups were not significantly different in age, gender or medications. The number of segments with perfusion defects was significantly higher in groups II and III than group I (group III, 2.9 +/- 1.5; group II, 2.9 +/- 2.1; and group I, 1.8 +/- 1.4, p = 0.009). Prior myocardial infarction, abnormal left ventricular ejection fraction, and multivessel CAD were more common in group III than in groups I and II. Stepwise discriminant analysis of 15 relevant clinical, angiographic and exercise scintigraphic descriptors showed that the number of thallium perfusion defects, abnormal LV ejection fraction at rest and multivessel CAD to be important predictors of hypotensive BP response. Multivariate analysis, however, showed that the number of thallium perfusion defects was the only important predictor of the hypotensive response. Thus, it is the functional significance of CAD assessed by the extent of thallium perfusion abnormalities rather than the extent of CAD or left ventricular dysfunction at rest that determines the systolic BP response to exercise.

The use of rest and exercise radionuclide ventriculography in risk stratification in patients with suspected coronary artery disease

The study examined the value of rest and exercise radionuclide ventriculography in risk stratification in patients with suspected coronary artery disease. There were 604 patients, 474 men and 130 women, aged 55 +/- 11 years (mean +/- standard deviation). At a follow-up of 18 +/- 10 months, there were 43 hard cardiac events: 27 patients died of cardiac causes and 16 had nonfatal acute myocardial infarctions. Univariate and multivariate survival analysis of the 10 most important clinical and exercise variables identified the exercise left ventricular ejection fraction as the most important predictor of death and total cardiac events (chi 2 = 18.1 and 29.6, respectively). The exercise heart rate was a significant, independent, but much weaker predictor of cardiac death and total events (chi 2 = 8.4 and 3.9, respectively), while exercise tolerance was a significant independent predictor of cardiac death only (chi 2 = 6.4). Actuarial life table analysis showed that the risk for future cardiac events increased in stepwise fashion as the exercise ejection fraction decreased. Thus, the exercise left ventricular ejection fraction is a useful prognosticator in patients with suspected coronary artery disease. This finding has important implications in patient management.

Exercise systolic blood pressure: a powerful determinant of increased left ventricular mass in patients with hypertension

This study examines the relation between left ventricular mass determined by two-dimensional echocardiography and exercise blood pressure in patients with hypertension. Sixty-seven patients with hypertension and 19 normal subjects underwent treadmill exercise testing and two-dimensional echocardiography. The left ventricular mass index in the normal subjects was 80 +/- 10 g/m2 (mean +/- SD). Patients with hypertension were classified into two groups according to left ventricular mass: Group I (n = 42) had normal mass and Group II (n = 25) had increased mass (greater than 2 SD above the mean value in 19 normal subjects). There was a poor correlation between left ventricular mass and blood pressure at rest. However, a better correlation was found between left ventricular mass and exercise systolic blood pressure (r = 0.58, p less than 0.001) or the change in systolic blood pressure from rest to exercise (r = 0.48, p less than 0.001). Twenty-two (76%) of 29 patients with an exercise systolic blood pressure of 190 mm Hg or greater had an increased left ventricular mass index, whereas only 3 (8%) of 38 patients with an exercise systolic blood pressure of less than 190 mm Hg had an increased left ventricular mass index (p less than 0.0001). Thus, in patients with hypertension, left ventricular mass index is poorly related to blood pressure at rest, but is related to exercise systolic blood pressure. Patients with an exercise systolic blood pressure of 190 mm Hg or greater usually have an increased left ventricular mass. These findings may have therapeutic implications.

Prognostic implications of rest and exercise radionuclide ventriculography in patients with suspected or proven coronary heart disease

Rest and exercise radionuclide ventriculography were assessed for their value in predicting major cardiac events in patients with chest pain. Of 219 patients who were followed for up to 51 months, 42 had major cardiac events: 12 patients (5.5%) died, 5 (2.2%) sustained nonfatal myocardial infarction, and 25 (11.4%) had coronary arterial bypass grafting. Univariate and multivariate survival analysis revealed that exercise left ventricular ejection fraction was the best predictor for total major events and the resting ejection fraction to be the best predictor for death or nonfatal myocardial infarction. These two variables were strong predictors in the entire group of patients and in subgroups: patients with or without Q-wave infarction, patients with high probability of coronary artery disease and those with abnormal resting left ventricular function. Thus, radionuclide angiography provides important prognostic data that permits the physician to categorize patients with chest pain syndromes with respect to subsequent cardiac events. If validated, this model or a modification of it could identify patients at high risk of subsequent major cardiac events who are candidates for intensive follow up and therapy or further invasive evaluation, as well as patients at low risk of subsequent major cardiac events for whom standard follow up would be appropriate.

Thallium-201 myocardial scintigraphy and left ventricular function at rest in patients with rest angina pectoris

The purpose of this study was to examine the rest thallium-201 perfusion pattern during angina-free periods in 40 patients with rest angina pectoris secondary to coronary artery disease (greater than or equal to 70% diameter narrowing). Seventeen patients had previous Q wave myocardial infarction. The perfusion defects were considered fixed or reversible, depending on the absence or presence of redistribution in the 4-hour delayed images. There were 40 perfusion defects (26 fixed and 14 reversible) in 27 patients whereas 13 patients had normal scans. Reversible perfusion defects were present in 10 patients (25%). Of the 26 fixed perfusion defects, 17 did not have corresponding Q waves. Occluded vessels (63%) had more perfusion defects than vessels with subtotal occlusion (30%) (p less than 0.01). The perfusion defect size was larger in patients with lower ejection fraction than in patients with higher ejection fraction. We conclude: (1) perfusion defects are common in patients with rest angina and are reversible in 25% of patients indicating reduced regional coronary blood flow; (2) the degree of stenosis affects the presence of perfusion defect; (3) fixed defects may be present without corresponding Q waves; and (4) global left ventricular function is related to the size of perfusion defects.

Hemodynamic, angiographic and scintigraphic correlates of positive exercise electrocardiograms: emphasis on strongly positive exercise electrocardiograms

The results of treadmill exercise electrocardiograms were analyzed in 179 patients with coronary artery disease (greater than or equal to 50% diameter narrowing of one or more vessels). Exercise thallium-201 images were available in 141 of these patients. The exercise electrocardiograms were strongly positive in 51 patients, mildly positive (1 to 1.9 mm ST depression) in 28 patients, falsely negative in 23 patients and uninterpretable in 77 patients. The degree of exercise-induced ST depression did not correlate with left ventricular function, extent of coronary artery disease, exercise heart rates and rate-pressure product and extent of exercise-induced thallium-201 perfusion abnormality. However, the presence of a strongly positive exercise electrocardiogram only at heart rates of 140 beats/min or more or stage III or higher of the Bruce protocol was predictive of less extensive coronary disease and perfusion abnormalities. Thus, the magnitude of ST depression as such during exercise is not predictive of the extent of coronary disease, even in patients with 3 mm or greater ST depression. However, a strongly positive exercise electrocardiogram in the first two stages of the Bruce protocol or at a heart rate of less than 140 beats/min was related to the extent of coronary artery disease and impaired myocardial perfusion, and identified patients with more extensive coronary artery disease and jeopardized myocardium. Therefore, caution should be used in interpreting prognostic data on the basis of the degree of exercise-induced ST depression alone.