Correlation between resting ST segment depression, exercise testing, coronary angiography, and long-term prognosis

Digitized Electrocardiography Measurements Support the Biological Plausibility of the Pathological Significance of ST Segments in Athletes

OBJECTIVE

ST segment deviations around the isoelectric line are common findings in manifest cardiovascular disease. In athletes, ST elevation is common, while ST depression is considered rare. However, clinical studies in athletes have associated ST depression with myocardial fibrosis and fatty infiltration and ST elevation with pericarditis and myocarditis. This study aims to explore the association between resting ST segment deviations and resting heart rate, an indicator of training and autonomic tone and electrocardiography (ECG) markers of exercise training effect and cardiovascular health R and T wave amplitude.

DESIGN

Retrospective analysis of digitized ECG data.

SETTING

Institutional setting.

PARTICIPANTS

Seven thousand eight hundred thirty-six (male athletes = 4592, female athletes = 3244) healthy asymptomatic athletes (14-35 years).

MAIN OUTCOME MEASURES

A series of correlations and regressions were conducted between ST depression (<0.0 µV) and ST elevation (>0.0 µV), on R and T wave amplitudes, and heart rate in leads V2, V5, and aVF.

RESULTS

Positive correlations between ST elevation and R and T wave (S wave in V2) amplitudes and leads V5, V2, and aVF in male and female athletes (range of r = 0.1-0.54). In addition, there was a negative correlation between ST elevation and HR for male and female athletes. Finally, there was a negative correlation between ST depression and R wave and HR for male and female athletes in V5 (P < 0.01).

CONCLUSIONS

In athletes, ST segment elevation is correlated with R and T wave amplitudes and negatively correlated with HR. In addition, ST segment elevation is correlated with low heart rate, consistent with its higher prevalence in athletes. ST segment depression is not influenced by HR but is negatively associated with R and T wave amplitudes.

Performance and Interpretation of Office Exercise Stress Testing

In an era where cardiovascular disease continues to increase in prevalence, chest pain is a commonly encountered complaint in the outpatient setting. Clinicians are often tasked with the challenge of selecting the most appropriate screening tool in the evaluation of a patient with suspected coronary artery disease. With proper consideration of indications and contraindications, exercise electrocardiogram (ECG) stress testing is an accessible, cost-conscious, and validated outpatient diagnostic modality for predicting coronary artery disease.

Effect of Diffuse Subendocardial Hypoperfusion on Left Ventricular Cavity Size by 13N-Ammonia Perfusion PET in Patients With Hypertrophic Cardiomyopathy

Vasodilator-induced transient left ventricular (LV) cavity dilation by positron emission tomography (PET) is common in patients with hypertrophic cardiomyopathy (HC). Because most patients with PET-LV cavity dilation lack obstructive epicardial coronary artery disease, we hypothesized that vasodilator-induced subendocardial hypoperfusion resulting from microvascular dysfunction underlies this result. To test this hypothesis, we quantified myocardial blood flow (MBF) (subepicardial, subendocardial, and global MBF) and left ventricular ejection fraction (LVEF) in 104 patients with HC without significant coronary artery disease, using ¹³NH₃-PET. Patients with HC were divided into 2 groups, based on the presence/absence of LV cavity dilation (LVvolume_stress/LVvolume_rest >1.13). Transient PET-LV cavity dilation was evident in 52% of patients with HC. LV mass, stress left ventricular outflow tract gradient, mitral E/E', late gadolinium enhancement, and prevalence of ischemic ST-T changes after vasodilator were significantly higher in patients with HC with LV cavity dilation. Baseline LVEF was similar in the 2 groups, but LV cavity dilation⁺ patients had lower stress-LVEF (43 ± 11 vs 53 ± 10; p <0.001), lower stress-MBF in the subendocardial region (1.6 ± 0.7 vs 2.3 ± 1.0 ml/min/g; p <0.001), and greater regional perfusion abnormalities (summed difference score: 7.0 ± 6.1 vs 3.9 ± 4.3; p = 0.004). The transmural perfusion gradient, an indicator of subendocardial perfusion, was similar at rest in the 2 groups. Notably, LV cavity dilation⁺ patients had lower stress-transmural perfusion gradients (0.85 ± 0.22, LV cavity dilation⁺ vs 1.09 ± 0.39, LV cavity dilation^-; p <0.001), indicating vasodilator-induced subendocardial hypoperfusion. The stress-transmural perfusion gradient, global myocardial flow reserve, and stress-LVEF were associated with LV cavity dilation. In conclusion, diffuse subendocardial hypoperfusion and myocardial ischemia resulting from microvascular dysfunction contribute to development of transient LV cavity dilation in HC.

Impact of electrocardiographic interpretability on outcome in patients referred for stress testing

BACKGROUND

There is limited insight into the association of electrocardiographic interpretability with outcome in patients referred for stress testing.

METHODS

Exercise echocardiography was performed in 8226 patients with known or suspected coronary artery disease. Electrocardiograms were considered uninterpretable in the presence of left bundle-branch block (LBBB), left ventricular hypertrophy (LVH) with strain, repolarization abnormalities because of digitalis therapy, ventricular paced rhythm, preexcitation or ST depression ≥ 0.1 mV because of other causes. End points were all-cause mortality, cardiac death and hard cardiac events (i.e. cardiac death or nonfatal myocardial infarction).

RESULTS

A total of 2450 patients had uninterpretable electrocardiograms. During a follow-up period of 4.1 ± 3.5 years, there were 1011 deaths (of which 478 were cardiac deaths) and 1069 patients experienced a hard cardiac event. The 5-year rates of death, cardiac death and hard cardiac events were, respectively, 18.7%, 10.9% and 18.8% in patients with uninterpretable ECGs, compared with 9.5%, 4.1% and 10.9% in those with interpretable ECGs (P < 0.001). After covariate adjustment, lack of ECG interpretability remained an independent predictor of all-cause mortality (hazard ratio [HR] 1.25, 95% confidence interval [CI] 1.08-1.44, P = 0.002), cardiac death (HR 1.63, 95% CI 1.32-2.01, P < 0.001) and hard cardiac events (HR 1.28, 95% CI 1.11-1.47, P < 0.001). When the specific ECG abnormalities were included as covariates, LBBB, LVH and digitalis therapy remained predictors of cardiac death; LBBB and LVH were predictors of hard cardiac events, and LVH remained predictive of all-cause mortality.

CONCLUSION

Uninterpretable ECGs portend a worse prognosis in patients referred for stress testing.

Significance of lead strength during exercise testing

BACKGROUND

The aim of the study was to evaluate the contribution of relative lead strengths to exercise-induced ECG changes (ST depression) to predict the degree of myocardial ischemia as compared to the angiograms. This was accomplished by comparing the magnitude of ST depression to the ST/R ratio. Studies have shown that the diagnostic strength of a lead is directly related to the R wave amplitude and that sensitivity is significantly improved.

METHODS

Three hundred patients, who underwent treadmill exercise testing and coronary angiography revealing significant coronary narrowing (> or = 70% luminal diameter narrowing), were studied, along with 150 patients clear of significant coronary artery disease (<70% luminar diameter narrowing). Our goal was to determine the correlation between the relative lead strengths, using a constructed ST/R ratio, to exercise induced ECG changes (ST depression) to predict the presence of myocardial ischemia as compared to angiographic findings. Using a cutoff of 0.1 for the ST/R ratio, our data were compared to the sensitivity and specificity of 1.0 mm ST depression.

RESULTS

Overall sensitivity was improved for the ST/R ratio (84% vs 78%), while specificity was slightly decreased (81% vs 92%) in comparison to standard ST depression. When differentiating between R wave amplitudes, those with R wave < or = 10 mm showed significantly improved sensitivity (88% vs 54%) and a minor decrease in specificity (90% vs 92%). In those with R wave > or = 20 mm, the sensitivity of ST depression was higher (88% vs 71%) but the ST/R ratio was much more specific (88% vs 46%). No significant difference was observed when differentiating between male and female patients.

CONCLUSION

We found that the correction of ST depression for R wave amplitude results in improved sensitivity in patients with low R waves and specificity in patients with very tall R waves (R > or = 20 mm).

Resting ST-segment depression predicts exercise-induced subendocardial ischemia in patients with hypertrophic cardiomyopathy

BACKGROUND

Patients with hypertrophic cardiomyopathy (HCM) sometimes display characteristic electrocardiographic (ECG) findings at rest and develop subendocardial ischemia during exercise in the absence of coronary lesions. However, their relationship has not yet been fully clarified.

METHODS

Exercise Tc-99m-tetrofosmin myocardial scintigraphy was performed in 48 patients with non-obstructive HCM. We quantified transient left ventricular cavity dilation (LVCD) on exercise scintigrams, a parameter of subendocardial ischemia, and correlated the results with the ECG findings at rest and during exercise.

RESULTS

Transient LVCD occurred during exercise in 17 (35%) patients with HCM. Hemodynamic parameters during exercise did not differ between HCM patients with and without transient LVCD. Multiple logistic regression analysis showed that transient LVCD was significantly associated with ST-segment depression at rest (chi2=5.00, odds ratio=5.70, 95% confidence intervals 1.24-26.18, P=0.025) and a greater total number of leads with resting ST-segment depression (chi2=6.38, odds ratio=1.60, 95% confidence intervals 1.12-2.42, P=0.012). The degree of LVCD was correlated with the total number of leads with ST-segment depression at rest (P=0.002); the optimal cutoff for the diagnosis of transient LVCD was 3 with a sensitivity of 65%, a specificity of 90%, and an accuracy of 81%.

CONCLUSIONS

In patients with HCM, ST-segment depression at rest was accompanied by exercise-induced subendocardial perfusion abnormality as detected by myocardial scintigraphy. ST-segment depression at rest suggests that the subendocardium is predisposed to exertional ischemia.

Overview of exercise stress testing

Exercise stress testing is a non-invasive, safe and affordable screening test for coronary artery disease (CAD), provided there is careful patient selection for better predictive value. Patients at moderate risk for CAD are best served with this kind of screening, with the exception of females during their reproductive period, when a high incidence of false positive results has been reported. Patients with a high pretest probability for CAD should undergo stress testing combined with cardiac imaging or cardiac catheterization directly. Data from the test, other than ECG changes, should be taken into consideration when interpreting the exercise stress test since it has a strong prognostic value, i.e. workload, heart rate rise and recovery and blood pressure changes. Only a low-level exercise stress test can be performed early post myocardial infarction (first week), and a full exercise test should be delayed 4 to 6 weeks post uncomplicated myocardial infarction. The ECG interpretation with myocardial perfusion imaging follows the same criteria, but the sensitivity is much lower and the specificity is high enough to overrule the imaging part.

Correlation between the TIMI risk score and high-risk angiographic findings in non-ST-elevation acute coronary syndromes: observations from the Platelet Receptor Inhibition in Ischemic Syndrome Management in Patients Limited by Unstable Signs and Symptoms (PRISM-PLUS) trial

BACKGROUND

The TIMI risk score for unstable angina and non-ST elevation myocardial infarction is an effective tool for predicting the risk of death and ischemic events among patients with non-ST elevation acute coronary syndromes, as well as for identifying those who are likely to benefit most from low-molecular-weight heparin and glycoprotein IIb/IIIa inhibition.

METHODS

To explore the pathobiologic basis for this interaction, we evaluated the relationship between the risk score, assessed at presentation, and angiographic findings among patients with non-ST elevation acute coronary syndromes. Angiographic data regarding thrombus, epicardial flow, and lesion severity were available for 1491 patients from the angiographic substudy of PRISM-PLUS.

RESULTS

Patients with risk scores of 5 to 7 (N = 435) were more likely to have a severe culprit stenosis (81% vs 58%, P < .001) and multivessel disease (80% vs 43%, P < .001) compared to those with scores of 0 to 2 (N = 220). The probability of left main disease (P = .01), visible thrombus, and impaired flow in the culprit lesion also increased progressively with rising risk scores (P < .001). Of the risk indicators that comprise the score, history of coronary disease, advanced age, and ST changes showed the strongest association with severe epicardial disease. Positive biomarkers of necrosis, ST changes, and prior aspirin use emerged as stronger correlates of visible thrombus and/or impaired culprit artery flow.

CONCLUSIONS

The TIMI risk score identifies patients who are more likely to have intracoronary thrombus, impaired flow, and increased burden of coronary atherosclerosis. These findings likely explain in part the particular benefit of potent antithrombin and antiplatelet agents among patients with higher risk scores.

Bedside diagnosis of coronary artery disease: a systematic review

PURPOSE

To assess the accuracy of bedside findings for diagnosing coronary artery disease and acute myocardial infarction.

METHODS

A MEDLINE search was performed to retrieve articles published from January 1966 to January 2003 that were relevant to the bedside diagnosis of coronary disease in adults.

RESULTS

In patients with stable, intermittent chest pain, the most useful bedside predictors for a diagnosis of coronary disease were found to be the presence of typical angina (likelihood ratio [LR]=5.8; 95% confidence interval [CI]: 4.2 to 7.8), serum cholesterol level >300 mg/dL (LR=4.0; 95% CI: 2.5 to 6.3), history of prior myocardial infarction (LR=3.8; 95% CI: 2.1 to 6.8), and age >70 years (LR=2.6; 95% CI: 1.8 to 4.0). Nonanginal chest pain (LR=0.1; 95% CI: 0.1 to 0.2), pain duration >30 minutes (LR=0.1; 95% CI: 0.0 to 0.9), and intermittent dysphagia (LR=0.2; 95% CI: 0.1 to 0.8) argued against a diagnosis of coronary disease. In patients with acute chest pain, the most important bedside predictors for a diagnosis of myocardial infarction were new ST elevation (LR=22; 95% CI: 16 to 30), new Q waves (LR=22; 95% CI: 7.6 to 62), and new ST depression (LR=4.5; 95% CI: 3.6 to 5.6). A normal electrocardiogram (LR=0.2; 95% CI: 0.1 to 0.3), chest wall tenderness (LR=0.3; 95% CI: 0.2 to 0.4), and pain that was pleuritic (LR=0.2; 95% CI: 0.2 to 0.3), sharp (LR=0.3; 95% CI: 0.2 to 0.5), or positional (LR=0.3; 95% CI: 0.2 to 0.5) argued against the diagnosis of myocardial infarction.

CONCLUSION

The accuracy of bedside predictors depends on the clinical setting. In the evaluation of stable, intermittent chest pain, a patient's description of pain was found to be the most important predictor of underlying coronary disease. In the evaluation of acute chest pain, the electrocardiogram was the most useful bedside predictor for a diagnosis of myocardial infarction. Aside from the extremes in cholesterol values, the analysis of traditional risk factors changed the probability of coronary disease or myocardial infarction very little or not at all.

Role of nondiagnostic exercise-induced ST-segment abnormalities in predicting future coronary events in asymptomatic volunteers

BACKGROUND

Whether exercise-induced ST-segment depression <1 mm is an independent predictor of future coronary events (CEs) in asymptomatic subjects is unknown.

METHODS AND RESULTS

We performed maximal treadmill exercise tests on 1083 volunteers from the Baltimore Longitudinal Study of Aging who were free from clinical coronary heart disease. Exercise ST-segment changes were stratified by Minnesota code criteria: 11:1 (n=213), flat or downsloping ST depression > or =1 mm; 11:2 (n=66), flat or downsloping ST depression > or =0.5 mm and <1 mm; 11:4 (n=124), ST-J depression > or =1 mm with slowly rising ST segments; and 11:5 (n=69), minor ST depression (<0.5 mm) before exercise that worsened to flat or downsloping ST depression > or =1 mm during or after exercise. Risk of CE was compared with subjects with normal exercise ECG (n=611). Over a mean follow-up of 7.9 years, 76 subjects developed CEs (angina pectoris, myocardial infarction, or coronary death). On univariate analysis, age (relative risk [RR]=1.07/year, P<0.0001), male sex (RR=1.98, P=0.009), plasma cholesterol (RR=1.02/mg per dL, P<0.0001), hypertension (RR=2.23, P=0.002), duration of exercise (RR=0.71/min, P=0.0001), and systolic blood pressure at peak effort (RR=1.02/mm Hg, P=0.002) were associated with CE. By Cox proportional hazards analysis, age (RR=1.06/year, P<0.0001), male sex (RR=2.76, P=0.0002), plasma cholesterol (RR=1.02 per 1 mg/dL, P<0.0001), duration of exercise (RR=0.87/min, P=0.004), and ST-segment changes coded as either 11:1 (RR=2.70, P=0.0005) or 11:5 (RR=2.73, P=0.04) were independent predictors of CE.

CONCLUSIONS

Both a classic ischemic ST-segment exercise response and intensification of minor preexercise ST-segment depression to levels > or =1 mm independently predicted future CE in this asymptomatic population. Neither slowly rising ST depression nor horizontal ST depression <1 mm was prognostic.

Stress test criteria used in the conservative arm of the FRISC-II trial underdetects surgical coronary artery disease when applied to patients in the VANQWISH trial

OBJECTIVES

We sought to determine whether the stringent stress test criteria for crossover to cardiac catheterization in the conservative arm of the Fast Revascularization During Instability in Coronary Artery Disease (FRISC-II) trial subjected this strategy to a disadvantage by failing to identify patients with surgical coronary artery disease (CAD).

BACKGROUND

In FRISC-II, an invasive strategy provided superior outcomes compared with a conservative strategy for patients with acute coronary syndromes. However, compared with the stress test criteria for crossover to catheterization in the Veterans Affairs Non-Q-Wave Infarction Strategies in Hospital (VANQWISH) trial, the FRISC-II criteria were more restrictive and did not use nuclear imaging or pharmacologic stress testing.

METHODS

We analyzed the conservative arm of VANQWISH to identify the prevalence of surgical CAD in those patients who met the VANQWISH, but not FRISC-II, criteria for catheterization.

RESULTS

Of 385 VANQWISH patients, 90 (23%) met the FRISC-II criteria for catheterization. Another 98 patients (25%) met only VANQWISH stress test criteria (60 patients by exercise and 38 by pharmacologic nuclear stress testing). Among subjects who underwent predischarge angiography, those meeting only VANQWISH stress test criteria had a high prevalence of surgical CAD (51%), comparable to patients who met FRISC-II criteria (54%, p = 0.805).

CONCLUSIONS

The overly stringent risk stratification protocol for conservative-arm patients in FRISC-II could have failed to identify almost as many patients with surgical CAD as it identified. A lower threshold for catheterization in the FRISC-II conservative patients might have improved their outcomes and therefore diminished the putative benefit of an invasive strategy.

Contemporary management of chronic stable angina

Chronic stable angina is a common condition with a prognosis that is less benign than is generally appreciated. The optimal treatment strategy of this disorder is unclear, and few anti-ischaemic agents have been rigorously tested in prospectively randomised mortality studies. The evidence base for the anti-ischaemic therapy of chronic angina draws upon data 'borrowed' from studies in acute coronary syndromes, and from studies in chronic angina using surrogate endpoints such as ambulatory silent ischaemia. Such evidence leads us to believe that anti-ischaemic therapy with beta-blockers offers a mortality benefit in chronic angina. In contrast, the mortality benefit of lipid lowering therapy and antiplatelet agents is well proven. Angioplasty offers no mortality benefit in the treatment of chronic angina, although it is more effective than medical therapy alone for the relief of symptoms. In a few patients with high order proximal coronary disease, coronary bypass surgery offers a distinct mortality advantage compared with medical treatment alone. Most patients, however, do not warrant such an approach, and only require surgery for when they remain symptomatic despite adequate medical therapy. Alternative strategies such as cardiac transplantation, transmyocardial laser revascularisation and spinal cord stimulation are now accepted in a subgroup of patients for the treatment of chronic angina refractory to standard therapy.

Cardiotocography only versus cardiotocography plus ST analysis of fetal electrocardiogram for intrapartum fetal monitoring: a Swedish randomised controlled trial

BACKGROUND

Previous studies indicate that analysis of the ST waveform of the fetal electrocardiogram provides information on the fetal response to hypoxia. We did a multicentre randomised controlled trial to test the hypothesis that intrapartum monitoring with cardiotocography combined with automatic ST-waveform analysis results in an improved perinatal outcome compared with cardiotocography alone.

METHODS

At three Swedish labour wards, 4966 women with term fetuses in the cephalic presentation entered the trial during labour after a clinical decision had been made to apply a fetal scalp electrode for internal cardiotocography. They were randomly assigned monitoring with cardiotocography plus ST analysis (CTG+ST group) or cardiotocography only (CTG group). The main outcome measure was rate of umbilical-artery metabolic acidosis (pH <7.05 and base deficit >12 mmol/L). Secondary outcomes included operative delivery for fetal distress. Results were first analysed according to intention to treat, and secondly after exclusion of cases with severe malformations or with inadequate monitoring.

FINDINGS

The CTG+ST group showed significantly lower rates of umbilical-artery metabolic acidosis than the cardiotocography group (15 of 2159 [0.7%] vs 31 of 2079 [2%], relative risk 0.47 [95% CI 0.25-0.86], p=0.02) and of operative delivery for fetal distress (193 of 2519 [8%] vs 227 of 2447 [9%], 0.83 [0.69-0.99], p=0.047) when all cases were included according to intention to treat. The differences were more pronounced after exclusion of 291 in the CTG+ST group and 283 in the CTG group with malformations or inadequate recording.

INTERPRETATION

Intrapartum monitoring with cardiotocography combined with automatic ST-waveform analysis increases the ability of obstetricians to identify fetal hypoxia and to intervene more appropriately, resulting in an improved perinatal outcome.

[Coronary artery bypass graft dysfunction--clinical presentation, laboratory and electrocardiographic parameters]

The recurrence of symptoms after coronary artery bypass surgery is often caused by bypass-dysfunction. In this study we tried to determine factors related to the long-term patency of arterial and venous bypass grafts. We evaluated all patients with bypass grafts undergoing coronary angiography in the year 1998 at our hospital (163 patients, mean age 67 years, mean interval since the operation 79 months, a total of 341 venous bypasses (VBP), 386 peripheral venous anastomoses and 85 arterial (LIMA = left internal mammarial artery) bypasses. The data were collected by a retrospective analysis of the hospital records. Statistics were performed using the Wilcoxon-Mann-Whitney-U test. After an interval of 53 months LIMA-bypasses were patent without stenosis in 92%. Symptoms were caused in only 2% by a dysfunction of the LIMA-graft. The patency of venous bypass grafts decreased with time (5 years after the operation 74% were patent without stenosis, 5-10 years 56%, more than 10 years 35%, p < 0.01). We found clear relations between the function of the venous grafts and the clinical presentation (patent grafts without stenosis in 43% with acute coronary syndromes, in 57% with stable angina [p = 0.08] and in 86% with atypical angina [p < 0.0001 for the difference between each of the first two and the last syndrome]), the resting-ECG (65% patent VBP without stenosis with normal ST-segments and 49% with abnormal ST-segments, p < 0.01), the body-mass-index (70% patent VBP without stenosis with a BMI < 25 and 56% with a BMI > 30, p = 0.05) and the erythrocyte sedimentation rate after 2 hours (79% patent VBP with an ESR < or = 20 mm vs. 64% with an ESR > 49 mm, p = 0.02). The function of VBP after coronary artery bypass graft (CABG)-procedure depends primarily upon the interval since the operation. In addition, we found correlations with clinical presentation, resting-ECG, body-mass-index and erythrocyte-sedimentation rate as a possible marker of inflammation in bypass-atherosclerosis. Therefore, inflammatory processes seem to play an important role in the development of venous graft dysfunction.

Fetal electrocardiogram waveform analysis in labour

The fetal electrocardiogram recorded during labour has so far been used for heart rate recording only. Extensive experimental, bioengineering and clinical research for more than 25 years on changes in the morphology of the electrocardiogram have provided more detailed information on fetal reactions to the stress and strain of labour. ST waveform analysis has been shown to provide new parameters that have the ability to monitor intrapartum hypoxia, thereby not only reducing the risk of the baby being born with hypoxia, but also significantly reducing the number of operative interventions.

Prognostic value of peak exercise systolic blood pressure on long-term survival after myocardial infarction

This study examined the association between peak exercise systolic blood pressure and other exercise test parameters and the long-term (19-year) survival of 625 patients with myocardial infarction who were original participants of the National Exercise and Heart Disease Project, a 3-year (1976 to 1979) multicenter randomized exercise clinical trial. Results show that low peak exercise systolic blood pressure (< or =140 mm Hg) was associated with increased mortality throughout the 19 years of follow-up, and men with this finding obtained no survival benefit from participating in an exercise program.

Exercise myocardial perfusion scintigraphy is useful for evaluating myocardial ischemia even in the elderly

Pharmacologic stress testing is recommended to elderly patients as a valuable alternative to exercise testing. We examined whether exercise testing is as useful for evaluating myocardial ischemia in the elderly as in the young. The consecutive 1,508 patients who underwent exercise 201Tl single-photon emission computed tomography (SPECT) were divided into six age groups: 6-29 years (n = 56), 30-44 (n = 143), 45-54 (n = 311), 55-64 (n = 498), 65-74 (n = 402), and 75-88 (n = 98). Both heart rate and rate-pressure product at peak exercise were significantly lower in patients aged 75-88 than in the other five groups. The frequency of ischemic ST depression was higher in patients aged 75-88 than in those aged 6-74, although the difference was not significant. Moreover, the frequency of 201Tl transient defect was significantly higher in patients aged 75-88 than in those aged 6-74. On the other hand, the sensitivity of ischemic ST depression for 201Tl transient defect was similar among the six groups, but the specificity was significantly lower in patients aged 75-88 than in those aged 6-74. In conclusion, exercise 201Tl SPECT is useful for evaluating myocardial ischemia even in the elderly, but exercise electrocardiography has limitations such as lower specificity in the elderly than 201Tl SPECT.

The effect of resting ST segment depression on the diagnostic characteristics of the exercise treadmill test

OBJECTIVES

The aim of this study is to demonstrate the effect of resting ST segment depression on the diagnostic characteristics of the exercise treadmill test.

BACKGROUND

Previous studies evaluating the effect of resting ST segment depression on the diagnostic characteristics of exercise treadmill test have been conducted on relatively small patient groups and based only on visual electrocardiogram (ECG) analysis.

METHODS

A retrospective analysis of data collected prospectively was performed on consecutive patients referred for evaluation of chest pain. One thousand two hundred eighty-two patients without a prior myocardial infarction underwent standard exercise treadmill tests followed by coronary angiography, with coronary artery disease defined as a 50% narrowing in at least one major epicardial coronary artery. Sensitivity, specificity, predictive accuracy and area under the curve of the receiver operating characteristic (ROC) plots were calculated for patients with and without resting ST segment depression as determined by visual or computerized analysis of the baseline ECG.

RESULTS

Sensitivity of the exercise treadmill test increased in 206 patients with resting ST segment depression determined by visual ECG analysis compared with patients without resting ST segment depression (77 +/- 7% vs. 45 +/- 4%) and specificity decreased (48 +/- 12% vs. 84 +/- 3%). With computerized analysis, sensitivity of the treadmill test increased in 349 patients with resting ST segment depression compared with patients without resting ST segment depression (71 +/- 6% vs. 42 +/- 4%) and specificity decreased (52 +/- 9% vs. 87 +/- 3%) (p < 0.0001 for all comparisons). There was no significant difference in the area under the curve of the ROC plots (0.66-0.69) or the predictive accuracy (62-68%) between the four subgroups.

CONCLUSIONS

The diagnostic accuracy and high sensitivity of the exercise treadmill test in a large cohort of patients with resting ST segment depression and no prior myocardial infarction support the initial use of the test for diagnosis of coronary artery disease. The classification of resting ST segment depression by method of analysis (visual vs. computerized) did not affect the results.

Risk stratification after acute myocardial infarction in the reperfusion era

Historically, risk stratification for survivors of acute myocardial infarction (AMI) has centered on 3 principles: assessment of left ventricular function, detection of residual myocardial ischemia, and estimation of the risk for sudden cardiac death. Although these factors still have important prognostic implications for these patients, our ability to predict adverse cardiac events has significantly improved over the last several years. Recent studies have identified powerful predictors of adverse cardiac events available from the patient history, physical examination, initial electrocardiogram, and blood testing early in the evaluation of patients with AMI. Numerous studies performed in patients receiving early reperfusion therapy with either thrombolysis or primary angioplasty have emphasized the importance of a patent infarct related artery for long-term survival. The predictive value of a variety of noninvasive and invasive tests to predict myocardial electrical instability have been under active investigation in patients receiving early reperfusion therapy. The current understanding of the clinically important predictors of clinical outcomes in survivors of AMI is reviewed in this article.

Gender differences in the relation between ST-T-wave abnormalities at baseline electrocardiogram and stress myocardial perfusion abnormalities in patients with suspected coronary artery disease

The presence of ST-T-wave abnormalities in the resting electrocardiogram was reported as a predictor of coronary artery disease (CAD) and increased morbidity and mortality. However, the independent value of ST-T abnormalities for predicting the presence and severity of perfusion abnormalities during stress testing has not been studied in a homogenous patient group without known CAD. We evaluated the relation between resting ST-T abnormalities and myocardial perfusion abnormalities in 246 patients (age 59 +/- 13 years, 114 men and 132 women) without known CAD or previous myocardial infarction referred for evaluation of possible myocardial ischemia by dobutamine (up to 40 microg/kg/min) stress sestamibi or tetrofosmin single-photon emission computed tomographic imaging. Resting ST-T abnormalities were present in 123 patients, whereas 123 patients with normal resting electrocardiograms served as a matched control group. Abnormal myocardial perfusion (fixed or reversible perfusion defects) was detected in 72% of men with and in 35% of men without resting ST-T abnormalities (p <0.0001), whereas the prevalence of myocardial perfusion abnormalities was not different in women with and without resting ST-T abnormalities (27% vs 23%, p = NS). In the entire population, independent predictors of an abnormal perfusion by multivariate analysis of clinical characteristics and risk factors were male gender (p <0.001, chi-square 10.5) and resting ST-T abnormalities (p <0.05, chi-square 3). Separate analysis of patients based on gender revealed resting ST-T abnormalities as independent predictors of abnormal perfusion in men (p <0.05, chi-square 4) but not in women. Stress perfusion defect score was higher in men with than without ST-T abnormalities (887 +/- 545 vs 207 +/- 180, p <0.001). It is concluded that resting ST-T wave abnormalities are associated with a higher prevalence and severity of resting and dobutamine-induced myocardial perfusion abnormalities in men but not in women. Resting ST-T wave abnormalities are powerful predictors of compromised myocardial perfusion independent of other clinical risk factors of CAD in men.

Predicting severe angiographic coronary artery disease using computerization of clinical and exercise test data

Currently the standard exercise test is shifting from being a tool for the cardiologist to utilization by the nonspecialist. This change could be facilitated by computerization similar to the interpretation programs available for the resting ECG. Therefore, we sought to determine if computerization of both exercise ECG measurements and prediction equations can substitute for visual analysis performed by cardiologists to predict which patients have severe angiographic coronary artery disease. We performed a retrospective analysis of consecutive patients referred for evaluation of possible or known coronary artery disease who underwent both exercise testing with digital recording of their exercise ECGs and coronary angiography at two university-affiliated Veteran's Affairs medical centers and a Hungarian hospital. There were 2,385 consecutive male patients with complete data who had exercise tests between 1987 and 1997. Measurements included clinical and exercise test data, and visual interpretation of the ECG paper tracings and > 100 computed measurements from the digitized ECG recordings and compilation of angiographic data from clinical reports. The computer measurements had similar diagnostic power compared with visual interpretation. Computerized ECG measurements from maximal exercise or recovery were equivalent or superior to all other measurements. Prediction equations applied by computer were only able to correctly classify two or three more patients out of 100 tested than ECG measurements alone. beta-Blockers had no effect on test characteristics while ST depression on the resting ECG decreased specificity. By setting probability limits using the scores from the equations, the population was divided into high-, intermediate-, and low-probability groups. A strategy using further testing in the intermediate group resulted in 86% sensitivity and 85% specificity for identifying patients with severe coronary disease. We conclude that computerized exercise ST measurements are comparable to visual ST measurements by a cardiologist and computerized scores only minimally improved the discriminatory power of the test. However, using these scores in a stratification algorithm allows the nonspecialist physician to improve the discriminatory characteristics of the standard exercise test even when resting ST depression is present. Computerization permitted accurate identification of patients with severe coronary disease who require referral.

Can computerization of the exercise test replace the cardiologist?

BACKGROUND

The type of practitioners who use the standard exercise test is changing. Once a tool of the cardiologist, the standard exercise test is now being performed by internists and other noncardiologists. Because this change could be facilitated by computerization similar to the computerized interpretation programs available for the resting electrocardiograph (ECG), we performed this analysis. A secondary aim was to demonstrate the effects of medication status and resting ECG abnormalities on test diagnostic characteristics because these factors affect utility of the exercise test by the generalist.

METHODS AND RESULTS

A retrospective analysis was performed of consecutive patients referred at 2 university-affiliated Veteran's Affairs Medical Centers and a Hungarian Hospital for evaluation of chest pain and possible ischemic heart disease. There were 1384 consecutive male patients without a prior myocardial infarction with complete data who had exercise tests and coronary angiography between 1987 and 1997. Measurements included clinical, exercise test data, and visual interpretation of the ECG recordings as well as more than 100 computed measurements from the digitized ECG recordings and compilation of angiographic data from clinical reports. The computer measurements had similar diagnostic power compared with visual interpretation. Computerized measurements from maximal exercise or recovery were equivalent or superior to all other measurements. Prediction equations applied by computer were superior to single ECG measurements. Beta-blockers had no effect on test characteristics, whereas resting ST depression was associated with decreased specificity and increased sensitivity.

CONCLUSIONS

Computerized exercise ST measurements are comparable to visual ST measurements by a cardiologist; computerized scores that included clinical and exercise test results exhibited the greatest diagnostic power. Applying scores with a computer allows the practicing physician to improve the diagnostic characteristics of the standard exercise test. This approach is successful even when there is resting ST depression, thus lessening the need for more expensive nuclear or imaging studies.

Ability of the exercise electrocardiogram test to detect ischemia in stable coronary artery disease patients with ST-segment depression on the resting electrocardiogram

BACKGROUND

The appearance of ST-segment depression on the exercise electrocardiogram (ETT) generally indicates myocardial ischemia. Disorders that produce ST-segment depression on the resting electrocardiogram can confound the results of the ETT. The purpose of this study was to assess the reliability of exercise ST-segment depression as an indicator of ischemia in patients with a resting electrocardiographic ST depression, presumably caused by coronary disease.

METHODS

We studied 882 patients 1 to 6 months after a hospitalization for myocardial infarction or unstable angina as part of the Multicenter Study of Myocardial Ischemia. An ETT and thallium-201 perfusion scan were performed in all patients. For the purpose of this study, the perfusion scan was considered the "gold standard" for ischemia. We correlated the ETT ST-segment responses with the perfusion scan in a group with a normal electrocardiogram baseline ST segment (NO ST DEP group) and in a group with resting electrocardiographic ST depression > or =0.5 mm (ST DEP group).

RESULTS

Although the frequency of ischemia by perfusion scan was similar in the ST DEP group (48%) to that in the NO ST DEP group (40%), the ST DEP group had a significantly higher (p = 0.03) sensitivity (54%) in detecting ischemia than the NO ST DEP group (35%). The ST DEP group, however, had a lower (58% vs 74%) specificity than the NO ST DEP group (p = 0.056). Baseline characteristics of the two groups probably account for these differences. The overall diagnostic accuracy is similar (58% vs 56%) in the two groups.

CONCLUSION

We conclude that in a stable population with known coronary disease, the presence of ST depression on the resting electrocardiogram does not impair the detection of ischemia by the ETT, but may be associated with a higher false-positive rate.

Perioperative ischemia and cardiac complications in major vascular surgery: importance of the preoperative twelve-lead electrocardiogram

PURPOSE

To investigate the associations between specific preoperative 12-lead electrocardiogram (ECG) abnormalities, perioperative ischemia, and postoperative myocardial infarction or cardiac death in major vascular surgery.

METHODS

Two prospective studies on perioperative myocardial ischemia performed in two tertiary university hospitals were combined to include 405 patients. All preoperative ECGs were analyzed according to the Sokolow-Lyon criteria for left ventricular hypertrophy by investigators who were blinded to the patients' perioperative clinical course. Perioperative myocardial ischemia was detected by continuous ECG recording, and postoperative cardiac complications included myocardial infarction and cardiac death.

RESULTS

A total of 19 postoperative cardiac complications occurred (two cardiac deaths and 17 myocardial infarctions). Voltage criteria for left ventricular hypertrophy (78 patients, 19%) and ST segment depression greater than 0.5 mm (98 patients, 24.2%) on preoperative ECGs were both significantly associated with postoperative myocardial infarction or cardiac death (odds ratio, 4.2 and 4.7; p = 0.001 and 0.0005, respectively) and with longer intraoperative and postoperative myocardial ischemia. In each of the two study groups, a preoperative ECG abnormality that involved voltage criteria, ST segment depression, or both (134 patients, 33.1%) was more predictive of postoperative cardiac complications than any other preoperative clinical variable, including a history of myocardial infarction or angina pectoris, diabetes mellitus, pathologic Q-wave by ECG, or preoperative myocardial ischemia. The combined duration of intraoperative and postoperative ischemia and the preoperative ECG with either voltage criteria or ST segment depression were the only independent factors associated with adverse cardiac events by multivariate analysis (p < or = 0.0001 and p = 0.02, respectively).

CONCLUSION

Left ventricular hypertrophy and ST segment depression on preoperative 12-lead ECGs are important markers of increased risk for myocardial infarction or cardiac death after major vascular surgery.

Prognostic implications of exercise echocardiography in women with known or suspected coronary artery disease

OBJECTIVES

The purpose of this study was to define the value of exercise echocardiography as an independent predictor of cardiac events in women with known or suspected coronary artery disease (CAD), incremental to the data provided by clinical evaluation and exercise testing.

BACKGROUND

Exercise echocardiography is more accurate than exercise electrocardiography for the identification of CAD in women. However, the prognostic implications of exercise echocardiography, especially relative to exercise electrocardiography, are undefined.

METHODS

Symptom-limited exercise echocardiography was performed in 549 consecutive women between 1989 and 1993. Echocardiography and electrocardiography were performed before and after treadmill exercise; an abnormal result on exercise electrocardiography was defined by ST segment depression > 0.1 mV, ischemia by exercise echocardiography as a new or worse wall motion abnormality after exercise and scar by akinesia or dyskinesia at rest. After exclusion of six patients with uninterpretable studies (1%) and 35 (6%) lost to follow-up, 508 women (mean [+/-SD] age 55 +/- 11 years) were followed up for 41 +/- 10 months for cardiac-related death, infarction or late revascularization.

RESULTS

The group attained 92 +/- 10% of age-predicted maximal heart rate, with an exercise capacity of 7 +/- 2 metabolic equivalents. Of 420 women with an interpretable electrocardiogram, significant ST segment changes were present in 68 (16%). Results of exercise echocardiography were normal in 413 (81%) women, positive for ischemia in 66 (13%) and scar only in 29 (6%). No events occurred in 444 patients (89%), and 19 underwent primary revascularization (within 3 months of exercise test). Cardiac events occurred in 36 women (7%), including 17 who died of cardia causes and 19 who had a myocardial infarction or required late revascularization for progressive symptoms. On univariate analysis, the variables associated with cardiac mortality and total cardiac events were a history of CAD, diabetes, left ventricular hypertrophy, exercise capacity and echocardiographic evidence of myocardial ischemia and infarction. A Cox proportional hazards model showed the independent predictors of outcome to be known CAD (odds ratio [OR] 6.6, 95% confidence interval [CI] 3.2 to 13.7, p < 0.00001) and echocardiographic ischemia (OR 4.3, 95% CI 2.1 to 8.7, p < 0.0001). The prognostic value of exercise echocardiography incremental to clinical and exercise variables was demonstrated using sequential Cox models.

CONCLUSIONS

In this large cohort of women, exercise echocardiography provided key prognostic information incremental to clinical and exercise testing data.

Cardiac catheter complications related to left main stem disease

OBJECTIVE

To examine the incidence and outcome of cardiac catheter complications related to left main coronary artery disease or damage using the CECCC (Confidential Enquiry into Cardiac Catheter Complications) database.

SETTING

Coordinating centre for national database.

DESIGN

Retrospective analysis of reports to a national multicentre database for cardiac catheter complications. Complications involving the left main coronary artery were flagged at entry. Where necessary additional information was sought from participating centres. 112,921 procedures were registered, 12,849 of which were coronary angioplasties and the remainder diagnostic studies.

RESULTS

The total number of cases for which complications were recorded was 993 (0.88%). In 61 (6.14%) of the 993 cases complications were associated with left main coronary disease or damage. In 57 (93%) of these 61 cases complications were major, necessitating resuscitation or immediate coronary bypass grafting. Ten patients (16%) died in the catheter laboratory, a further 9 (15%) within 24 hours, and a total of 23 patients (38%) died within one month of the procedure. Left main stem related complications account for 17% of total mortality in the CECCC database. Urgent coronary bypass grafting was attempted in 42 patients, of whom 31 were alive at one month. In all of the six reported PTCA-related complications the cause was traumatic damage to the left main coronary artery. Operators of all grades of seniority experienced complications in similar proportions.

CONCLUSIONS

The risk of a complication relating to the left main stem is relatively low, but when such complications occur they tend to be life-threatening and contribute a fifth of total catheter-related mortality. In the absence of a widely available non-invasive investigation with good predictive value for left main stem disease, the best safeguard is careful technique. Patients who do develop complications should have emergency coronary bypass grafting.

Asymptomatic Cardiac Ischemia Pilot (ACIP) study: impact of anti-ischemia therapy on 12-week rest electrocardiogram and exercise test outcomes. The ACIP Investigators

OBJECTIVES

This report from the Asymptomatic Cardiac Ischemia Pilot (ACIP) study examines differences in the magnitude of reduction of myocardial ischemia as determined by exercise treadmill testing in patients randomized to three different treatment strategies: angina-guided medical therapy, ischemia-guided medical therapy and coronary revascularization.

BACKGROUND

No prospective randomized clinical trials in patients with exercise electrocardiographic (ECG) abnormalities and asymptomatic cardiac ischemia on ambulatory ECG monitoring have compared the impact of different treatment strategies, including coronary revascularization, in terms of reducing myocardial ischemia.

METHODS

The ACIP exercise protocol was used. Exercise variables measured included final exercise stage; presence of exercise-induced angina or ischemia; time to angina; time to 1-mm ST segment depression; number of exercise ECG leads with abnormalities; maximal depth of ST segment depression in any lead; sum of ST segment depression; ST/HR index; and rate-pressure product at time to angina, at time to 1-mm ST segment depression and at peak exertion.

RESULTS

Peak exercise time was increased by 0.5, 0.7 and 1.6 min in patients assigned to the angina-guided, ischemia-guided and coronary revascularization strategies, respectively, from the qualifying visit to the 12-week visit (p < 0.001). At the qualifying visit, the sum of exercise-induced ST segment depression was 9.4 +/- 5.0 (mean +/- SD), 9.6 +/- 4.7 and 9.9 +/- 5.5 mm (p = NS) in the three treatment strategies, respectively. At the 12-week visit, the sum of exercise-induced ST segment depression was 7.4 +/- 5.7, 6.8 +/- 5.3 and 5.6 +/- 5.6 mm (p = 0.02) in the three treatment strategies, respectively. Each treatment strategy resulted in a significant reduction in all exercise-induced variables of myocardial ischemia measured at 12 weeks.

CONCLUSIONS

Coronary revascularization significantly reduced the extent and frequency of exercise-induced myocardial ischemia compared with either medical strategy. The prognostic impact of these observations should be evaluated in a large-scale multicenter clinical trial.

Correlation of resting electrocardiographic ST-T wave abnormalities with exercise thallium-201 stress testing in patients with known or suspected coronary artery disease

Resting ST-T wave abnormalities have been associated with an increased risk of adverse cardiac events. Because increased myocardial ischemia represents a possible mechanism for these abnormalities, this study sought to determine whether patients with resting ST-T have greater myocardium in jeopardy as evidenced by stress-induced thallium-201 perfusion abnormalities. One hundred thirty-two consecutive patients not taking digitalis were prospectively studied with combined symptom-limited exercise testing and quantitative thallium-201 imaging. Patients with (n = 43) versus without (n = 89) resting ST-T were older and more frequently had diabetes mellitus. No difference between the 2 groups was seen with respect to gender, cardiac medications, systemic hypertension, prior myocardial infarction, or coronary artery bypass surgery. The results of stress testing were similar for the 2 groups with respect to maximal heart rate, maximal blood pressure, and METs achieved. The mean depth of ST depression was similar in the 2 groups, although patients without resting ST-T were more likely to have upsloping ST depression, and had a shorter duration of ST depression after exercise. With use of an 11 segment model analysis of stress and rest planar thallium-201 scintigrams, patients with versus without resting ST-T had significantly more scan segments showing redistribution defects (1.1 +/- 1.7 vs 0.5 +/- 1.1; p = 0.03) and total (both redistribution and persistent) defects (2.5 +/- 2.5 vs 1.3 +/- 1.9; p = 0.002). The lung-heart ratios (normal < 0.51) were similar in the 2 groups (0.44 +/- 0.07 vs 0.43 +/- 0.10; p = 0.44).(ABSTRACT TRUNCATED AT 250 WORDS)

Prediction of severe coronary artery disease using computerized ECG measurements and discriminant function analysis

This study tested the hypothesis that discriminant function analysis of clinical and exercise-test variables including computerized ST measurements could improve the prediction of severe coronary artery disease. Secondary objectives were to demonstrate the effect of digoxin and/or resting electrocardiographic (ECG) abnormalities, and to evaluate the relative importance of ST measurements made during the recovery phase and in the three lead group areas. The design was a retrospective analysis of data collected during exercise testing and coronary angiography. The ECG data were gathered and stored in digital format on optical discs and all ST measurements were made off-line using the authors' own software. Univariate and multivariate analytic methods were used to analyze all pretest characteristics as well as hemodynamic and computerized ECG responses to exercise. A 1,000-bed Veterans Affairs Medical Center served as the setting. The study included 446 male veterans who underwent a sign or symptom limited treadmill exercise test and coronary angiography. Analysis was also performed on a subset of this population formed by excluding patients receiving digoxin or with resting ECGs exhibiting left ventricular hypertrophy or ST depression (n = 328). In the total study population, the authors derived a treadmill score using discriminant function analysis. This score included: (1) the time-slope area in lead V5 during recovery; (2) delta heart rate; (3) angina pectoris during the exercise test; and (4) presence of diagnostic Q waves on the resting ECG. This score was effective in predicting triple vessel/left main disease and outperformed exercise-induced ST depression for predicting severe coronary artery disease. After exclusion of patients with ECGs exhibiting left ventricular hypertrophy or resting ST depression and patients receiving digoxin, discriminant function analysis chose: (1) the time-slope area in lead V5 during recovery and (2) delta heart rate. Exclusion of these patients resulted in a nonsignificant decrease in specificity of all ST criteria. ST-segment amplitude or slope in lead V5 at 3.5 minutes in recovery clearly outperformed the maximal exercise measurements in both groups. Summing the depressions or selecting the most depression in the three areas (ie, lateral-V5, inferior-II, anterior-V2) did not improve test performance. Leads other than V5 did not contain significant diagnostic information. A quantitative approach to exercise testing using discriminant function analysis enhanced the tests' performance for predicting severe coronary disease. The inclusion of patients taking digoxin or with resting ECG abnormalities nonsignificantly decreases the specificity of all ST criteria.(ABSTRACT TRUNCATED AT 400 WORDS)