An agreement approach to predict severe angiographic coronary artery disease with clinical and exercise test data

The prognostic value of estimating stroke volume before and after exercise during treadmill stress echocardiography

BACKGROUND

Stress echocardiography (SE) is an established technique for assessment of coronary artery disease (CAD) which is difficult to perform and interpret. Left ventricular stroke volume (SV) is readily estimated with Doppler echocardiography. It can be affected by myocardial ischemia, with possible adjunctive value during SE.

METHODS

Patients underwent Bruce protocol SE with SV estimated before and after maximal treadmill exertion post routine regional wall analysis. Incremental change in SV (ΔSV) with exercise was measured.

RESULTS

A derivation cohort (n = 273) was established to test the hypothesis. An optimal cutoff for detection on inducible ischemia was ΔSV ≤ +10 mL. The validation cohort of consecutive patients (n = 1093, 376 [34%] female; age 59 ± 12 years) were followed clinically after SE for 20 460 patient-months. There were 1000 patients with nonischemic SE, and 93 patients with studies suggestive of myocardial ischemia. Secondary analysis yielded 831 patients with a normal exercise response (ΔSV > +10 mL) and 192 with an abnormal ΔSV ≤ +10 mL. Time to first combined adverse cardiac event (composite of angina, acute coronary syndrome, cardiac revascularization, worsening New York Heart Association (NYHA) class, a reduction in EF, and cardiovascular death) was analyzed and adjusted using Cox proportional hazards regression. The hazard ratio for an adverse event with an abnormal ΔSV response (≤10 mL) was 10.3 (95% confidence intervals 5.6-19.1, P < .0001).

CONCLUSIONS

Stroke volume assessment during SE is feasible and readily performed. It is simple, practical, and has incremental diagnostic and prognostic value when added to exercise regional wall-motion analysis.

The Prognostic Value of the Diastolic Stress Test in Patients Undergoing Treadmill Stress Echocardiography

BACKGROUND

Exercise stress echocardiography (SE) is well validated for the evaluation of myocardial ischemia. Diastolic stress testing (DST) is recommended in the 2016 American Society of Echocardiography and European Association of Cardiovascular Imaging Guidelines for unexplained dyspnea. This study's aim was to prognostically evaluate the DST prospectively in a large stress testing population.

METHODS

Patients underwent SE with mitral E/e' measured before and after maximal treadmill exertion to estimate diastolic function. Patients were divided into four groups: group 1 (n = 201)-ischemic; group 2 (n = 1,563)-negative DST (E/e'_pre < 12, E/e'_post < 12); group 3 (n = 68)-positive DST (E/e'_pre < 12, E/e'_post ≥ 12); group 4 (n = 314)-high baseline E/e' (E/e'_pre ≥ 12).

RESULTS

Consecutive patients (n = 2,201, 770 [35%] female; 58 ± 12 years) were followed after SE for 27,964 patient-months. Time to first heart failure event (composite of heart failure admission, worsening New York Heart Association class, worsening ejection fraction, or cardiovascular death) was analyzed and adjusted using Cox proportional hazards regression. Ischemic patients hazard ratio (HR) was 28, 95% CI, 17-44, P < .0005, for subsequent heart failure compared with negative DST patients. Nonischemic, positive DSTs were highly predictive (HR = 4.2; 95% CI, 1.6-11.0; P = .001); while high E/e'_pre was not predictive (HR = 1.3; 95% CI, 0.7-2.4; P = .49) of future heart failure events.

CONCLUSIONS

DST differentiates heart failure prognosis in patients with induced diastolic dysfunction. Ischemia predictably portends the worst heart failure outcomes, and nonischemic, positive diastolic stress tests predicted more events compared with negative tests. These prognostic data support and add to the recommendations of the 2016 guidelines.

Diagnosis and Screening of Coronary Artery Disease

Diagnostic testing for CAD is aided by the calculation of the pretest probability using either the Diamond-Forrester score or the Morise score. Patients who have a low risk of CAD should not undergo testing. Exercise ECG testing should be reserved for patients who have pretest probabilities lower than 20%, because a negative test does not adequately reduce the posttest probability of significant CAD. For patients who are at intermediate risk, either nuclear perfusion imaging or stress echocardiography is an acceptable choice depending on local availability and practice. Due to its low specificity, CAC scoring is currently limited in its usefulness for the diagnosis of CAD in symptomatic patients. Currently, screening for CAD among patients at low risk should not extend beyond screening for traditional risk factors. Physicians should use the Framingham Risk Score to stratify patients into levels of 10-year risk for cardiac events. Due to its high rate of false positive tests and low sensitivity, exercise ECG is of limited value in screening. Among patients with higher levels of risk, in whom further risk stratification would be of use in making decisions about risk factor management, measurement of CAC either with EBCT or multidetector row CT scanning is a promising option, but more research is required before its use should become widespread. Measures of endothelial function are in development but lack data to support their widespread use currently.

Prognostic value of the Duke Treadmill Score in diabetic patients

BACKGROUND

The Duke Treadmill Score (DTS) is an established clinical tool for risk stratification of coronary artery disease. We sought to assess the prognostic value of the DTS in diabetics compared with nondiabetics in this study.

METHODS

We studied 100 diabetics and 202 age- and sex-matched nondiabetic controls without known coronary artery disease risk stratified by DTS and followed for a median duration of 6.6 years. The association between DTS and primary, secondary outcomes, composite events, and rate of coronary angiography was tested.

RESULTS

Survival free from cardiac death, nonfatal myocardial infarction, congestive heart failure, or early and late revascularization was 89%, 54%, and 13%, respectively, in the low-, intermediate-, and high-risk categories of diabetic group (P < .0001), and 91%, 57%, and 17%, respectively, in the low- to high-risk groups of nondiabetics (P < .0001). During follow-up, diabetics had more secondary events (P = .011) and coronary angiography (P < .001) compared with nondiabetics. The DTS was a strong independent predictor of composite events in both diabetics (P < .001) and nondiabetics (P < .001). A significant number of diabetics were classified as intermediate risk and had a significantly higher incidence of coronary angiography (87.5% vs 70.8%, P = .032) and late revascularizations (35.4% vs 15.3%, P = .011) within this risk group compared with nondiabetics. Survival free from major adverse cardiac events differed significantly across the 3 Duke risk groups for diabetics (P = .002) but not for controls (P = .07). Survival free from composite events differed significantly across the 3 Duke risk groups for both diabetics and nondiabetics (P < .0001). Overall, diabetics had higher rates of major adverse cardiac events, composite events (P = .011), and coronary angiography (P < .001) than nondiabetics. The DTS is a strong predictor of survival free of composite events in both groups by multivariate analysis.

CONCLUSIONS

The DTS predicted survival free from MACE and composite events equally well in patients with and without diabetes.

Prognostic value of the Duke treadmill score in the elderly

OBJECTIVES

The purpose of this study was to test the hypothesis that the Duke treadmill score works less well for risk stratification in patients age 75 years or above.

BACKGROUND

Although the Duke treadmill score is generally effective for risk stratification, its prognostic value in the elderly may be limited because they have a higher prevalence of coronary artery disease (CAD), more severe CAD and a lower exercise tolerance.

METHODS

The study population consisted of 247 patients age 75 years or above, and the control population consisted of 2,304 patients below 75 years of age. All patients were symptomatic, had undergone exercise thallium testing between 1989 and 1991 and were followed for a median of >6.5 years. The Cox regression model was used to test the association of the Duke score (utilized both as a continuous variable and using previously published risk group cutoffs) with outcomes (cardiac death, nonfatal myocardial infarction [MI], late revascularization).

RESULTS

Using the Duke score to risk-stratify the elderly, 26% were in the low risk group, 68% were in the intermediate risk group and 6% were in the high risk groups; seven-year cardiac survival was 86%, 85% and 69%, respectively (p = 0.45). There was also no significant association between these Duke score risk groups and all other outcome end points in the elderly. The Duke score as a continuous variable did not predict cardiac death (p = 0.43) or cardiac death or MI (p = 0.42), but did predict total cardiac events (which included late revascularization) (p = 0.0027). For the control population, more patients (55%) were in the low risk group, and the Duke score (as a continuous variable or in risk groups) was highly predictive of all end points (p = 0.0001).

CONCLUSIONS

The Duke score predicted cardiac survival in younger patients but not in patients age 75 years or above. The majority of the elderly were classified as intermediate risk by the Duke score. Only a minority of the elderly were classified as low risk, but this group still had an annual cardiac mortality of 2%/year.

A basic approach to the interpretation of the exercise test

To interpret the exercise test, the following parameters need to be evaluated: the heart rate and blood pressure response, symptoms, dysrhythmias, aerobic capacity, and evidence for myocardial ischemia. When analyzing the ST segment for ischemia, the amount and type of ST depression and the time of onset and resolution are examined. The exercise test results are best used to determine a post-test probability that the patient has significant coronary disease, predict its severity, and provide a prognosis of the patient. The test allows primary care physicians to decide which patients with coronary artery disease can be safely managed medically and which high-risk patients need further evaluation and consideration for revascularization.

Predictions of coronary artery stenosis by artificial neural network

Data from angiography patient records comprised 14 input variables of a neural network. Outcomes (coronary artery stenosis or none) formed both supervisory and output variables. The network was trained by backpropagation on 332 records, optimized on 331 subsequent records, and tested on final 100 records. If 0.40 was chosen as the output distinguishing stenosis from no stenosis, 81 patients who had stenosis would have been identified, while 9 of 19 patients who did not have stenosis might have been spared angiography. The results demonstrated that artificial neural networks could identify some patients who do not need coronary angiography.

Identification of severe coronary artery disease in patients with a single abnormal coronary territory on exercise thallium-201 imaging: the importance of clinical and exercise variables

OBJECTIVES

The aim of this study was to determine which clinical, exercise and thallium variables can aid in the identification of three-vessel or left main coronary artery disease (3VLMD) in patients with one abnormal coronary territory (either a reversible or fixed defect) on exercise thallium testing and to test the prognostic value of these variables.

BACKGROUND

Although the sensitivity of detection of coronary artery disease by thallium-201 imaging is high, the actual detection of 3VLMD by thallium tomographic images alone is not optimal.

METHODS

A multivariate model for prediction of 3VLMD was developed from several clinical, exercise and thallium-201 variables in a training population of 264 patients who had one abnormal coronary artery territory on exercise thallium testing and had undergone coronary angiography. Using this model, patients were stratified into risk groups for prediction of 3VLMD. A separate validation cohort of 474 consecutive patients who were treated initially with medical therapy and who had one abnormal coronary territory were divided into identical risk groupings by the variables derived from the training population, and they were followed for a median of 7.0 years to evaluate the prognostic value of this model.

RESULTS

The prevalence of 3VLMD was 26% in the training population despite one abnormal thallium coronary territory. Four clinical and exercise variables--diabetes, hypertension, magnitude of ST segment depression, and exercise rate-pressure product-were found to be independent predictors of 3VLMD. In the training population, the prevalence of 3VLMD in low-, intermediate- and high-risk groups was 15%, 22% and 51%, respectively. When the multivariate model was applied to the validation population, the eight-year overall survival rates in the low-, intermediate- and high-risk groups were 89%, 73% and 75%, respectively (p < 0.001).

CONCLUSIONS

A substantial proportion of patients with one abnormal thallium coronary territory have 3VLMD with subsequent divergent outcomes based upon risk stratification by clinical and exercise variables. Consequently, the finding of only a single abnormal coronary territory by thallium-201 perfusion imaging does not necessarily confer a benign prognosis in the absence of consideration of nonimaging variables.