Usefulness of ST-segment depression as a sign of coronary artery disease when confined to the postexercise recovery period

Significance of 'recovery ST-segment depression' in exercise stress test

Objective

To study the significance of ST-segment depression during ‘recovery’ compared to that ‘during stress’ and ‘both the phases’ in exercise stress test.

Methods

Patients with positive exercise stress test who underwent coronary angiography (CAG) from 1st January 2017 to 31st December 2018 were studied. Patients were divided into 3 groups- Group A with ST-depression restricted to recovery phase, group B with ST-depression restricted to stress phase and group C with ST-depression seen both during exercise and recovery. All patients underwent CAG. Sensitivity, specificity, and predictive values of each of these groups in diagnosis of significant coronary artery disease (CAD) were analysed and compared.

Results

Total 300 patients were studied. Mean age of the study population was 48.77 ± 7.94 years. 78.3% of patients with positive exercise stress test had significant CAD. 96% of patients in group A had significant CAD, which was higher than in group B (88.9%) & group C (70.1%). The specificity, positive predictive value and negative predictive value of ST-segment depression in group A (96.92%, 96% and 25.2% respectively) were higher than that of ST-depression in group B (89.23%, 88.89% and 24.47% respectively) and group C (13.85%, 70.05% and 7.96% respectively). Sensitivity and accuracy of ST-depression in group A were lower (20.43% and 37% respectively), compared to other 2 groups.

Conclusion

Patient with ST-depression restricted to recovery phase had highest specificity, positive predictive value, and negative predictive value. However, accuracy was highest in group with both stress phase and exercise ST-segment depression.

The Clinical Utility of Cardiopulmonary Exercise Testing in Suspected or Confirmed Myocardial Ischemia

Heart disease is a major cause of morbidity and mortality in the United States, with coronary artery disease (CAD) representing more than half of all cardiovascular events. Stable patients presenting with symptoms suggestive of CAD are likely to undergo an exercise electrocardiogram (ECG) and/ or imaging study as a first-line diagnostic assessment. A cardiopulmonary exercise test (CPX) is an ECG stress test plus ventilatory gas analysis. Recently, CPX has been used to detect exercise-induced myocardial ischemia (EIMI) suggestive of underlying CAD. Two CPX variables, oxygen pulse (VO2/HR) and the slope of oxygen consumption versus work rate (Δ VO2/ Δ WR), have been identified to be especially indicative of EIMI. Currently, there are a number of diagnostic tests available for the identification of CAD, with the most widely used being stress ECG, stress myocardial perfusion imaging (MPI) and echocardiography, and cardiac catheterization. Exercise ECG, although inexpensive, has a number of well-recognized limitations, including low sensitivity resulting in false-negative results. Stress (exercise or pharmaceutically induced) MPI and catheterization are more accurate but also more invasive and expensive. It appears that CPX may improve the diagnostic accuracy of exercise ECG. This review will address the potential utility of CPX in patients with suspected or confirmed myocardial ischemia.

Asymptomatic ST-segment depression during exercise testing and the risk of sudden cardiac death in middle-aged men: a population-based follow-up study

AIMS

Silent electrocardiographic ST change predicts future coronary events in patients with coronary heart disease (CHD), but the prognostic significance of asymptomatic ST-segment depression with respect to sudden cardiac death in subjects without apparent CHD is not well known.

METHODS AND RESULTS

We investigated the association between silent ST-segment depression during and after maximal symptom-limited exercise test and the risk of sudden cardiac death in a population-based sample of 1769 men without evident CHD. A total of 72 sudden cardiac death occurred during the median follow-up of 18 years. The risk of sudden cardiac death was increased among men with asymptomatic ST-segment depression during exercise [hazard ratio (HR) 2.1, 95% confidence interval (CI) 1.2-3.9] as well as among those with asymptomatic ST-segment depression during recovery period (HR 3.2, 95% CI 1.7-6.0). Asymptomatic ST-depression during exercise testing was a stronger predictor for the risk of sudden cardiac death especially among smokers as well as in hypercholesterolaemic and hypertensive men than in men without these risk factors.

CONCLUSION

Asymptomatic ST-segment depression was a very strong predictor of sudden cardiac death in men with any conventional risk factor but no previously diagnosed CHD, emphasizing the value of exercise testing to identify asymptomatic high-risk men who could benefit from preventive measures.

Significance of QRS duration changes in the evaluation of ST-segment depression presenting exclusively during the postexercise recovery period

BACKGROUND

The aim of this study was to evaluate the contribution of QRS prolongation in the diagnosis of coronary artery disease (CAD) in patients with exercise-induced ST-segment depression exclusively during the recovery period.

METHODS

The study population consisted of 107 patients (90 males and 17 females) aged 39-70 (mean 59 +/- 7) years who underwent a treadmill exercise test using Bruce protocol and presented ST-segment depression limited to the recovery period. Angiographic data were available for all studied patients.

RESULTS

Among studied patients, 74 (69%) were found to have hemodynamically significant CAD, while the remaining 33 (31%) had normal coronary arteries. Concomitant QRS prolongation was revealed in 61 (82%) of the patients with angiographically documented CAD, while in 13 (18%) patients QRS duration remained unchanged. On the contrary, only 4 (12%) of the 33 patients with normal coronary arteries showed prolonged QRS duration during ST depression, while in the remaining 29 (88%) QRS duration remained unchanged.

CONCLUSIONS

The evaluation of the concomitant QRS duration changes may discriminate patients with truly ischemia-induced ST-segment depression limited to the recovery period.

Diagnostic and prognostic value of ST segment depression limited to the recovery phase of exercise stress test

OBJECTIVES

To investigate the diagnostic and prognostic value of ST segment depression limited to the recovery phase of an exercise stress test, as compared with that of ST segment depression appearing during exercise.

SETTING

Exercise stress test laboratory of a university hospital.

PATIENTS AND DESIGN

Clinical and angiographic data were compared for 574 consecutive patients who developed ST segment depression during the active phase of an exercise test (group 1) and for 79 patients who developed ST segment depression only during the recovery phase of the exercise test (group 2).

RESULTS

There were no differences between the two groups in major clinical features. Significant coronary artery stenoses were found in 488 group 1 patients (85%) and in 62 group 2 patients (78%, p = 0.14). Three vessel or left main disease was found in 166 (29%) group 1 and in 14 (18%) group 2 patients (p = 0.045). At a median follow up of 55.3 months of 321 group 1 and 54 group 2 patients, there were no significant differences in major cardiac events between the groups (univariate relative risk 0.81, 95% confidence interval 0.25 to 2.68, p = 0.72).

CONCLUSION

The diagnostic and prognostic power of ST segment depression limited to the recovery phase of an exercise test is largely similar to that of ST segment depression induced during effort; thus, assessing ST segment depression during recovery can significantly improve the clinical information derived from exercise stress tests.

Exercise-induced silent myocardial ischemia and coronary morbidity and mortality in middle-aged men

OBJECTIVES

We investigated the prognostic significance of exercise-induced silent myocardial ischemia in both high and low risk men with no prior coronary heart disease (CHD).

BACKGROUND

Silent ischemia predicts future coronary events in patients with CHD, but there is little evidence of its prognostic significance in subjects free of CHD.

METHODS

We investigated the association of silent ischemia, as defined by ST depression during and after maximal symptom-limited exercise test, with coronary risk in a population-based sample of men with no prior CHD followed for 10 years on average.

RESULTS

Silent ischemia during exercise was associated with a 5.9-fold (95% CI 2.3 to 11.8) CHD mortality in smokers, 3.8-fold (95% CI 1.9 to 7.9) in hypercholesterolemic men and 4.7-fold (95% CI 2.4 to 9.1) in hypertensive men adjusting for other risk factors. The respective relative risks (RRs) of any acute coronary event were 3.0 (95% CI 1.7 to 5.1), 1.9 (95% CI 1.2 to 3.1) and 2.2 (95% CI 1.4 to 3.5). These associations were weaker in men without these risk factors. Furthermore, silent ischemia after exercise was a stronger predictor for the risk of acute coronary events and CHD death in smokers and in hypercholesterolemic and hypertensive men than in men without risk factors.

CONCLUSIONS

Exercise-induced silent myocardial ischemia was a strong predictor of CHD in men with any conventional risk factor, emphasizing the importance of exercise testing to identify asymptomatic high risk men who could benefit from risk reduction and preventive measures.

Effect of coronary collateral circulation on exercise stress test

In this study, patients who have recovery-only ST segment depression in exercise stress test were chosen. It is proposed that coronary collateral circulation could improve with stress-increased coronary perfusion, and accordingly, patients with recovery-only ST segment depression were evaluated by coronary angiography for grading the coronary collateral circulation. Twenty-one men and five women were assigned to the study group. Sixteen men and two women who had exercise-induced ST segment depression were assigned to the control group. Age and gender of both groups were not statistically different (p>0.05). The reason for terminating the exercise stress test was chest pain in two of 26 patients in the study group versus 15 of 18 in the control group (p<0.001). In both groups coronary collateral frequency and grade were directly correlated with the severity of the coronary artery disease (p<0.001 in the study group, and p<0.05 in the control group). When both groups were compared for the frequency of significant coronary collateral circulation, 14 of 26 patients in the study group versus 4 of 18 patients in the control group had significant coronary collateral circulation (p=0.035). The authors conclude that recovery-only ST segment depression correlates well with the frequency of significant coronary collateral circulation, and coronary collaterals may prevent myocardial ischemia during exercise.

Independent prognostic significance of ischemic ST-segment response limited to recovery from treadmill exercise in asymptomatic subjects

BACKGROUND

Although exercise-induced ST depression is an independent predictor of future coronary events in asymptomatic populations, the predictive value of ST depression beginning after exercise cessation is unknown.

METHODS AND RESULTS

We analyzed the treadmill exercise tests of 825 healthy volunteers who were 22 to 89 years of age from the Baltimore Longitudinal Study of Aging. All subjects were free from coronary heart disease by history, physical examination, and resting ECG. From 825 participants, 611 (group 0) had no ischemic ST-segment changes during or after treadmill exercise, while 214 subjects developed > or = 1-mm flat or downsloping ST depression: 151 (group 1) had ST changes starting during exercise, and 63 (group 2) had changes limited to recovery. Groups 1 and 2 were similar in age, sex, smoking status, hypertension prevalence, fasting plasma glucose, and serum cholesterol (CHOL). However, both groups were older and had higher CHOL and prevalence of hypertension than group 0. Treadmill exercise duration, peak oxygen consumption, and maximal heart rate were similar between groups 1 and 2 but were lower than in group 0 (each P < 0.05). During a mean follow-up time of 9 years, 55 subjects developed coronary events (angina pectoris, myocardial infarction, or coronary death): 21 of 611 (3.4%) in group 0, 22 of 151 (14.6%) in group 1, and 12 of 63 (19%) in group 2 (P = 0.001). By survival analysis, the risk of coronary events was similar in groups 1 and 2 but significantly higher than in group 0 (P < 0.0001). Multiple logistic regression showed that age (odds ratio [OR] = 1.07 per year, P = 0.00001), CHOL (OR = 1.02 per 1 mg, P = 0.0001), and presence of ST-segment depression (OR = 2.59, P = 0.007 and OR = 2.38, P = 0.04 for groups 1 and 2, respectively) were independent predictors of events.

CONCLUSIONS

Thus, ischemic ST-segment changes developing during recovery from treadmill exercise in apparently healthy individuals have adverse prognostic significance similar to those appearing during exercise.

Value of analysis of the evolution of the pattern of the ST segment in exercise electrocardiograms

We analysed retrospectively the exercise electrocardiogram records of all patients with positive exercise tests which, on subsequent coronary angiography, proved to be "false positives". The exercise records of 10 "false positive" patients were compared with the records of 10 patients with true positive tests in the setting of single vessel disease and 20 patients with true positive tests and multivessel disease. Patients proving to be false positives did not differ from those with true positive tests in respect to either the slope of the ST segment, the number and site of leads showing shift of the ST segment, or the peak exercise double product. The total duration of exercise, however, was significantly longer in patients having false positive tests (7.93 minutes SD 1.34) as compared to true positive results (5.95 minutes SD 1.9 in single vessel disease, and 4.4 minutes SD 2.2 in multivessel disease, P = less than 0.05). Eight of 10 patients having a false positive test showed an atypical evolution of the pattern of the ST segment. Seven had rapid normalization of depression of the ST segment immediately after cessation of exercise, while one showed shift of the ST segment only during the period of recovery. In contrast, 28 of 30 patients with true positive tests showed gradual normalization of the depressed ST segment during the period of recovery. We conclude that shifts in the ST segment that normalize rapidly on cessation of exercise are frequently a false positive finding.

Recovery-phase patterns of ST segment depression in the heart rate domain. Identification of coronary artery disease by the rate-recovery loop

Although the time course of ST segment depression after exercise has been related to the presence and severity of coronary artery disease, recovery-phase patterns of ST segment depression with reference to changing heart rate have not been quantified. We have found distinct recovery loop patterns of ST segment depression that distinguish subjects without coronary disease from patients with coronary artery disease when ST segment depression is examined in the heart rate domain. Continuous plots of ST segment depression and heart rate were constructed throughout treadmill exercise and recovery in 100 clinically normal subjects, in 124 patients with coronary artery disease proven by catheterization, and in 17 patients with no significant coronary disease at catheterization. Among clinically normal subjects, 95% (95 of 100) had normal (clockwise) rate-recovery loops, and 5% (five of 100) had abnormal (counterclockwise) rate-recovery loops. In these normal subjects, the resulting 95% specificity of a normal rate-recovery loop was similar to the 93% (93 of 100) specificity of standard end-exercise ST segment depression criteria. Among patients with coronary disease proven by angiography, 93% (115 of 124) had abnormal (counterclockwise) rate-recovery loops, and 7% (nine of 124) had normal rate-recovery loops. In contrast was the significantly lower 74% (92 of 124) sensitivity of standard ST segment criteria (p less than 0.001 vs. the rate-recovery loop). Specificity of a normal rate-recovery loop (71%, 12 of 17) and standard ST segment depression criteria (71%, 12 of 17) were similar in the patients with normal coronary arteries at angiography.(ABSTRACT TRUNCATED AT 250 WORDS)