Low Pre-test Probability Of Coronary Artery Disease Research Articles

Abstract 12386: The Prevalence of Coronary Microvascular Dysfunction Among Patients With Low Pretest Probability of Coronary Artery Disease

Introduction: Coronary microvascular dysfunction (CMD) is an underdiagnosed cause of chest pain. The 2021 AHA/ACC guidelines do not advocate for testing in patients with chest pain and low pretest probability (PTP <15%) of coronary artery disease (CAD). The prevalence of CMD among patients with low pretest probability is not known. We sought to estimate the prevalence of CMD among patients with chest pain and a low pretest probability of CAD. Methods: We reviewed all the patients referred to positron emission tomography myocardial perfusion imaging (PET-MPI) from May 2011 to January 2022. Patients with chest pain and low PTP of CAD who had normal PET-MPI were included in the analysis. Rest and peak myocardial blood flows (MBF) were measured. Coronary flow reserve (CFR) was calculated as a ratio of peak/rest MBF. CMD was defined as CFR of <2. Results: 1873 patients (age 53.7 ± 9.3 years, 23.6% males) with low PTP and normal PET-MPI were included in the analysis. 372 (20%) patients had MVD. Patients with CMD had lower use of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, aspirin, and statin. Diabetes, hypercholesterolemia, and hypertension did not predict CMD. However, female gender (OR: 1.7 95%CI: 1.1- 2.6, p=0.016), age (OR: 1.02 95%CI: 1.00 - 1.04, p=0.023) and BMI (OR: 1.04 95%CI: 1.02 - 1.07, p=0.001) were associated with higher likelihood of MVD. Conclusions: Coronary Microvascular Dysfunction is common among patients with chest pain, low PTP of CAD, and normal myocardial perfusion imaging. Females are more likely to have CMD. Further studies are needed to verify the prognostic value of this population.

Highly sensitive troponin I assay in the diagnosis of coronary artery disease in patients with suspected stable angina.

BACKGROUNDEvaluation of suspected stable angina patients with probable coronary artery disease (CAD) in the community is challenging. In the United Kingdom, patients with suspected stable angina are referred by community physicians to be assessed by specialists within the hospital system in rapid access chest pain clinics (RACPC). The role of a highly sensitive troponin I (uscTnI) assay in the diagnosis of suspected CAD in a RACPC in a “real-life” setting in a non-academic hospital has not been explored. AIMTo examine the diagnostic value of uscTnI (detection limit 0.12 ng/L, upper reference range 8.15 ng/L, and detected uscTnI in 96.8% of the reference population), in the evaluation of stable CAD in a non-selected patient group, with several co-morbidities, who presented to the RACPC. METHODSOne hundred and seventy two RACPC patients were assigned to either functional or anatomical testing according to the hospital protocol.RESULTSThe investigations offered to patients were exercise tolerance test 7.6%, 24 h ECG 1.2%, Echocardiogram 14.5%, stress echocardiogram 8.1%, coronary computed tomography angiography (CCTA) 12.8%, coronary angiogram 13.4%, 17.4% were diagnosed with non-cardiac chest pain, 3.5% treated as stable angina, 8.2% reviewed by cardiologists, electronic medical records were not available in 10.4%. Receiver operating characteristic curves for CAD used uscTnI values measured in patients who underwent functional testing, angiogram or CCTA. Values > 0.52 ng/L showed 100% sensitivity and at > 11.6 ng/L showed 100% specificity. In the range > 0.52-11.6 ng/L, uscTnI may not have the same diagnostic potential. In patients assigned to coronary angiogram higher concentrations of uscTnI was associated with severe CAD. Low levels of uscTnI and low pre-test probability of CAD (QRISK3) may decrease patient numbers assigned to CCTA.CONCLUSIONThe uscTnI diagnostic cut-off values in a RACPC will depend on patient population and their presenting co-morbidity. In the presence of clinical comorbidities and previous CAD the uscTnI needs to be used in conjunction with clinical assessment.

Imaging functional stress test for stable chest pain symptoms in patients at low pretest probability of coronary artery disease: Current practice and long-term outcome.

Stress testing in patients with low pretest probability (PTP) of coronary artery disease (CAD) has become an increasing practice, potentially leading to underestimation of its true clinical value. Our aim was to describe the current use of most employed imaging functional tests and their prognostic value. We selected patients with low PTP of CAD (CAD consortium clinical score<15%) who underwent exercise or dipyridamole stress echocardiography or single photon emission computed tomography for suspected angina. Main exclusions were age<45, known CAD, and abnormal rest wall motion. Of the 2279 subjects undergoing stress test, 883 (39%) had low PTP, and 91 (10.3%) had a positive test for ischemia. After a median follow-up of 5.8years, 36 patients had events (21 died, 14 had nonfatal myocardial infarction). The percentage of events in the abnormal and normal stress test groups were similar (5 [5.5%] vs 31 [3.9%], P=ns), as the annualized event rate (0.87% vs 0.62%, P=ns). Age was the only variable associated with outcome in the regression analysis (hazard ratio 1.072, 95% CI 1.034-1.113, P<0.001). An abnormal result was not associated with worse outcome in each of the subgroups of functional tests. In our geographical area, a considerable proportion of patients undergoing imaging functional tests for stable chest pain have a low estimated PTP of CAD. Of these, 1 in 10 resulted positive for inducible ischemia. However, none of the most common imaging functional tests, single photon emission computed tomography (SPECT), and stress echocardiography offer prognostic information in these patients.

Value of the coronary artery disease consortium rule in patients with acute chest pain and negative troponins referred for exercise stress testing.

To assess the value of the pretest probability (PTP) of coronary artery disease (CAD) for predicting stress testing results and coronary events in patients with acute chest pain and negative troponins. A total of 3527 patients without a history of CAD referred to our chest pain unit with suspected acute coronary syndromes, nondiagnostic ECGs, and negative troponin levels underwent exercise stress testing. PTP was estimated with the CAD consortium prediction rule, and was categorized as low (<15%), low-intermediate (15-65%), intermediate-high (66-85%), and high (>85%). The endpoints were the presence of signs of inducible myocardial ischemia on stress testing and the occurrence of coronary events within 6 months. The probability of exercise-induced myocardial ischemia was 2.6, 12.6, 42.9, and 82.1% in patients with low, low-intermediate, intermediate-high, and high PTP, respectively (Ptrend<0.001). The cumulative rate of coronary events within 6 months was also significantly lower in patients with low PTP of CAD (0.8%) than in those with low-intermediate (6.9%), intermediate-high (32.5%), or high PTP (66.7%) (Ptrend<0.001). Per 10% increment in PTP of CAD, the adjusted odds ratios for inducible myocardial ischemia and coronary events within 6 months were, respectively, 1.71 (95% confidence interval: 1.61-1.85) and 1.87 (95% confidence interval: 1.74-2.01). PTP was associated strongly with the likelihood of exercise-induced myocardial ischemia and coronary events in patients with suspected acute coronary syndromes and negative troponins. The yield of stress testing in the subset of patients with low PTP was very low.

Frequency and Determinants of Inappropriate Use of Treadmill Stress Test for Coronary Artery Disease.

BackgroundIn developing countries like Pakistan, treatment is mediated by private and public healthcare setups with a limited budget for health facilities. Moreover, the inappropriate use of treadmill tests imposes a burden on healthcare resources and leads to unwarranted interventions. Our aim is to assess the prevalence and predictors of inappropriate referrals for the exercise tolerance test (ETT) to diagnose coronary artery disease (CAD) while taking public and private healthcare settings into consideration.MethodsA cross-sectional study was conducted to find the prevalence of the inappropriate use of ETT to diagnose obstructive CAD and to determine the factors responsible for it. A total of 264 patients were enrolled from outpatient departments in Karachi. The inclusion criterion was the referral of treadmill testing for the diagnosis of CAT. The analysis was performed by logistic regression models to ascertain independent predictors of inappropriate use.ResultsExercise stress tests were found to be inappropriate in 209 (79%) patients. The study indicated that the majority of patients had a low or very low pre-test probability of CAD. Diabetes, hypertension, and dyslipidemia were less frequent in the inappropriate as compared to the appropriate referrals (10%, 45%, and 16% versus 20%, 69%, and 32%). Both public and private sectors showed a high prevalence of inappropriate testing, but it was much higher in the latter (27% versus 73%, P < 0.001). In all regression models, the private healthcare system was the major independent predictor for inappropriate indications of ETT with an average odds ratio of 4.9 (P < 0.001).ConclusionThe high prevalence of ETT referrals was found for the diagnosis of CAD. This result was consistent with both public and private healthcare systems, but it was considerably higher in private setups. Comorbidities, number of risk factors, and cardiovascular risk were not associated with the inappropriate use of ETT.

Prevalence and factors associated with inappropriate use of treadmill exercise stress test for coronary artery disease: a cross-sectional study.

BackgroundIn some countries, the public health system has less availability when compared to the population covered by health insurance. In addition, inappropriate referrals for treadmill exercise stress test increase spending and lead to unnecessary interventions. We aim to determine the prevalence and characteristics of inappropriate referrals for treadmill exercise stress tests in the assessment of coronary artery disease (CAD), considering public and private health systems scenarios.MethodsA cross-sectional design was used to describe the frequency of inappropriate use of exercise testing in the diagnosis of CAD and to determine its predictors. We consecutively enrolled 191 patients from two outpatient facilities in Northeast Brazil. For inclusion, the exercise testing should be referred for the assessment of CAD. We performed logistic regression models to identify independent predictors of inappropriate use.ResultsTreadmill exercise stress tests were rated as inappropriate in 150 (78 %) patients. The majority of patients had low or very low pre-test probability of CAD. Presence of hypertension, diabetes and dyslipidemia were more frequent in the appropriate than inappropriate indications (71 %, 19 % and 29 % versus 43 %, 8 % and 16 %, respectively). Tests performed both at the public and private system showed high prevalence of inappropriate examinations, higher in the latter (57 % versus 87 %, P < 0.001). The private health system was the major independent predictor of inappropriate referral, consistent in all regression models (when adjusting for clinical variables, OR = 4.3; P < 0.001).ConclusionThe vast majority of treadmill exercise stress test referrals in the assessment of CAD were inappropriate. The availability of the method and not the estimate probability of CAD appear to be the underlying condition for a treadmill test referral.

Diagnostic role of coronary calcium scoring in the rapid access chest pain clinic: prospective evaluation of NICE guidance

Coronary artery calcium (CAC) imaging by unenhanced computed X-ray tomography (CT) is recommended as an initial diagnostic test for patients with stable chest pain symptoms but a low likelihood (10-29%) of underlying obstructive coronary artery disease (CAD) after clinical assessment. The recommendation has not previously been tested prospectively in a rapid access chest pain clinic (RACPC). We recruited 300 consecutive patients presenting with stable chest pain to the RACPC of three hospitals. All patients underwent CAC imaging, followed by invasive coronary angiography (ICA) in patients with CAC ≥ 1000 Agatston units (Au) and CT coronary angiography (CTCA) in those with CAC <1000. Patients with 50-70% stenosis on CTCA underwent myocardial perfusion scintigraphy (MPS) while those with ≥ 70% stenosis underwent ICA. Obstructive CAD was defined as ≥ 70% stenosis on ICA or the presence of inducible ischaemia on MPS. Patients were followed up clinically for a mean of 17 (SD 6) months. The mean patient age was 60.6 (SD 9.6) years and 48% were males. Obstructive CAD was found in 56 (19%) patients, of whom 42 (14%) underwent revascularization. CAC was zero in 131 (44%) patients, of whom two (1.5%) had obstructive CAD and one (0.8%) underwent revascularization. The sensitivity, specificity, negative predictive value, and positive predictive value of CAC ≥ 1 for detection of obstructive CAD were 96, 53, 32, and 98%, respectively. None of the 57 patients with low pre-test probability of CAD and zero CAC had obstructive CAD or suffered a cardiovascular event during the follow-up. Patients with stable chest pain symptoms but a low likelihood of CAD can safely be diagnosed as not having obstructive CAD in the absence of detectable coronary calcification by unenhanced CT. Patients with CAC >400 Au have a high prevalence of obstructive CAD and further investigation with ICA or functional imaging may be warranted rather than CTCA. These findings support NICE guidance for the investigation of stable chest pain. ClinicalTrials gov identifier: NCT01464203.

Accuracy of dual-source CT to identify significant coronary artery disease in patients with uncontrolled hypertension presenting with chest pain: comparison with coronary angiography

It has been previously reported that the sensitivity and specificity of multislice CT for detecting significant CAD (coronary artery disease) is high. Chest pain is a common presentation in patients with uncontrolled hypertension. We investigated the sensitivity and specificity of dual-source CT to detect and rule out significant CAD in patients presenting with uncontrolled hypertension accompanied by chest pain. 260 consecutive patients presenting with acute chest pain in the context of stage 2 hypertension (systolic pressure ≥160 and/or diastolic pressure ≥100) were enrolled in the study. After admission, control of blood pressure and risk stratification, 82 patients were excluded due to renal insufficiency, prior coronary revascularisation or refused participation in the study. 90 further patients with low pre-test probability of CAD were also excluded. 88 remaining patients were subjected to CT coronary angiography using dual-source CT (Definition, Siemens Medical Solutions, Forchheim, Germany) within 24 h before invasive coronary angiography. A contrast-enhanced volume dataset was acquired (120 kV, 400 mAs/rot, collimation 2 × 64 × 0.6 mm, retrospective ECG gating). Data sets were evaluated concerning the presence or absence of significant coronary stenoses and validated against invasive coronary angiography. A significant stenosis was assumed if the diameter reduction was ≥50%. 88 patients (mean age 66 ± 11 years, mean heart rate 61 ± 9 bpm) were evaluated regarding the presence or absence of significant CAD (at least one stenosis ≥50% diameter reduction). Mean systolic blood pressure on presentation was 203 ± 20 mmHg and mean diastolic blood pressure was 103 ± 13 mmHg. On a per patient basis, the sensitivity and specificity for dual-source CT to detect significant CAD in vessels >1.5 mm diameter was 100% (36/36, 95% CI 90-100) and 90% (47/52, 95% CI 79-97), respectively with a negative predictive value (NPV) of 100% (47/47, 95% CI 92-100) and a positive predictive value (PPV) of 88% (36/41, 95% CI 74-96). On a per artery basis, 352 vessels were evaluated (left main, left anterior descending, left circumflex and right coronary artery in 88 patients, 12 vessels could not be assessed due to either motion artefacts or heavy calcification and were considered positive for stenoses) with a sensitivity of 84% (54/64, 95% CI 72-95) and specificity of 94% (272/288, 95% CI 88-100); NPV was 96% (272/282, 95% CI 90-100) and PPV was 77% (54/70, 95% CI 62-91). Our study demonstrates high sensitivity, specificity and negative predictive value of dual-source CT to detect significant CAD in patients presenting with uncontrolled hypertension accompanied by chest pain. Dual-source CT angiography may be useful to safely rule out coronary artery stenoses and avoid invasive angiograms in these patients.

Reference Ranges for LVEF and LV Volumes from Electrocardiographically Gated 82Rb Cardiac PET/CT Using Commercially Available Software

Electrocardiographic gating is increasingly used for (82)Rb cardiac PET/CT, but reference ranges for global functional parameters are not well defined. We sought to establish reference values for left ventricular ejection fraction (LVEF), end systolic volume (ESV), and end diastolic volume (EDV) using 4 different commercial software packages. Additionally, we compared 2 different approaches for the definition of a healthy individual. Sixty-two subjects (mean age +/- SD, 49 +/- 9 y; 85% women; mean body mass index +/- SD, 34 +/- 10 kg/m(2)) who underwent (82)Rb-gated myocardial perfusion PET/CT were evaluated. All subjects had normal myocardial perfusion and no history of coronary artery disease (CAD) or cardiomyopathy. Subgroup 1 consisted of 34 individuals with low pretest probability of CAD (<10%), and subgroup 2 comprised 28 subjects who had no atherosclerosis on a coronary CT angiogram obtained concurrently during the PET/CT session. LVEF, ESV, and EDV were calculated at rest and during dipyridamole-induced stress, using CardIQ Physio (a dedicated PET software) and the 3 major SPECT software packages (Emory Cardiac Toolbox, Quantitative Gated SPECT, and 4DM-SPECT). Mean LVEF was significantly different among all 4 software packages. LVEF was most comparable between CardIQ Physio (62% +/- 6% and 54% +/- 7% at stress and rest, respectively) and 4DM-SPECT (64% +/- 7% and 56% +/- 8%, respectively), whereas Emory Cardiac Toolbox yielded higher values (71% +/- 6% and 65% +/- 6%, respectively, P < 0.001) and Quantitated Gated SPECT lower values (56% +/- 8% and 50% +/- 8%, respectively, P < 0.001). Subgroup 1 (low likelihood) demonstrated higher LVEF values than did subgroup 2 (normal CT angiography findings), using all software packages (P < 0.05). However, mean ESV and EDV at stress and rest were comparable between both subgroups (p = NS). Intra- and interobserver agreement were excellent for all methods. The reference range of LVEF and LV volumes from gated (82)Rb PET/CT varies significantly among available software programs and therefore cannot be used interchangeably. LVEF results were higher when healthy subjects were defined by a low pretest probability of CAD than by normal CT angiography results.

962-62 The Use of Exercise-Rest Same Day SPECT Sestamibi Imaging Protocol in Coronary Artery Disease Detection

There are several sestamibi imaging protocols, each with certain perceived advantages and limitations. Most published reports are on patients (pts) in clinical trials which may have a hidden bias in pt selection. This study examined our clinical experience using the exercise (10 mCi)/rest (30 mCi) same day SPECT protocol with sestamibi in 132 pts with coronary artery disease (CAD) by angiography and 61 pts with low pre-test probability of CAD. There were 670 pts studied during the same time period but not included because they did not meet the above two criteria. The rest study was combined with first-pass RNA using the Sim-minus;400 gamma camera in 72 pts. There were 112 men and 20 women aged 60 ± 11 years. The pts weight was 179 ± 27 Ibs and height was 68 ± 3 inches. The exercise was adequate (≥ 85% of maximum predicted heart rate or positive S-T response) in 85 pts and submaximal in 47 pts. The overall sensitivity of SPECT was 88% (compared to 27% for S-T depression, P = 0.0001); it was 76% in one-vessel, 84% in two- and 98% in three-vessel disease (P = 0,006). The normalcy rate in 61 pts with low probability of CAD was 95%. The perfusion defects in 116 pts with abnormal images were reversible (complete or partial) in 80 pts and fixed in 36 pts. The left ventricular ejection fraction was 50 ± 12% in pts with reversible and 39 ± 9% in pts with fixed defects (P = 0.0003). In the 72 pts with RNA, there were 15 segments with fixed defects. The wall motion was normal in 2 segments, and abnormal in 13. In 129 segments with no fixed defects, the wall motion was normal in 97 (75%). Thus, the exercise-rest same day sestamibi protocol provides a high diagnostic accuracy for CAD detection and high quality functional studies. The protocol may also eliminate the need for rest studies in pts whose exercise studies are normal.