Stress-only Myocardial Perfusion Imaging Research Articles

Stress-only versus rest-stress SPECT MPI in the detection and diagnosis of myocardial ischemia and infarction by machine learning.

Rest-stress SPECT myocardial perfusion imaging (MPI) is widely used to evaluate coronary artery disease (CAD). We aim to evaluate stress-only versus rest-stress MPI in diagnosing CAD by machine learning (ML). A total of 276 patients with suspected CAD were randomly divided into training (184 patients) and validation (92 patients) cohorts. Variables extracted from clinical, physiological, and rest-stress SPECT MPI were screened. Stress-only and rest-stress MPI using ML were established and compared using the training cohort. Then the diagnostic performance of two models in diagnosing myocardial ischemia and infarction was evaluated in the validation cohort. Six ML models based on stress-only MPI selected summed stress score, summed wall thickness score of stress%, and end-diastolic volume of stress as key variables and performed equally good as rest-stress MPI in detecting CAD [area under the curve (AUC): 0.863 versus 0.877, P = 0.519]. Furthermore, stress-only MPI showed a reasonable prediction of reversible deficit, as shown by rest-stress MPI (AUC: 0.861). Subsequently, nomogram models using the above-stated stress-only MPI variables showed a good prediction of CAD and reversible perfusion deficit in training and validation cohorts. Stress-only MPI demonstrated similar diagnostic performance compared with rest-stress MPI using 6 ML algorithms. Stress-only MPI with ML models can diagnose CAD and predict ischemia from scar.

Optimizing stress-only myocardial perfusion imaging: a clinical prediction model to improve patient selection.

Stress-only single photon emission computed tomography myocardial perfusion imaging (MPI) offers numerous advantages in terms of improved workflow, cost and radiation reduction but is currently not widely utilized due to challenges in selecting appropriate patients for this technique. Data from 5959 individuals were used to derive (N = 4018) and validate (N = 1941) a binomial logistic regression model to predict normal stress MPI studies (stress total perfusion deficit < 4%, ejection fraction ≥ 50%). Model performance was analyzed using receiver operator characteristic curves. A simplified point-scoring system was developed and its impact on imaging workflow was assessed. Significant predictors of abnormal vs. normal stress MPI included male sex, age > 65 years, cardiomyopathy, congestive heart failure, myocardial infarction, angina, and pharmacological stress. The final model and simplified scoring system were associated with areas under the curve of 0.81 (95% CI 0.79-0.83) and 0.80 (95% CI 0.79-0.82) in the validation group, respectively. Use of the scoring system was estimated to result in a decrease of 56.5% in the number of non-contributory imaging studies acquired with minimal patient rescheduling. A prediction tool derived from simple clinical information can identify candidates for stress-only MPI studies with a beneficial impact on departmental workflow.

The incremental value of coronary artery calcium score in predicting long-term prognosis and defining the warranty period of normal adenosine stress-only myocardial perfusion imaging using CZT SPECT.

Normal stress-only (SO) myocardial perfusion imaging (MPI) using SPECT reduces imaging time and radiation dose with a good prognosis. However, the long-term prognostic value of combining coronary artery calcium score (CACS) with SO MPI to determine the warranty period remains unknown. Hence, we assessed the incremental prognostic value of CACS and its impact on the warranty period of normal SO MPI using SPECT. We retrospectively included 1375 symptomatic patients without a history of coronary artery disease (CAD) and a normal SO MPI using adenosine who underwent simultaneous CAC scoring. Annual major adverse cardiac events (MACE) rates were calculated for CACS categories: 0, 1-399, 400-999, and ≥1000. The mean age was 60.0 ± 11.8 years (66.9% female) with a median follow-up of 10.3 [IQR 9.6-10.9] years. The warranty period for annual MACE rate for normal SO SPECT extended the total follow-up time in years. MACE rate categorized by CAC categories demonstrated an increase in MACE rates with increasing CACS; CACS 0 and CACS 1-399 were associated with a 10-year warranty period, CACS 400-999 had a warranty period of 4 years and no warranty period could be given for CACS≥1000 (5.9 % at 1 year). CACS as an adjunct to normal pharmacological SO MPI provides additional prognostic information and aids in determining a warranty period.

Diagnostic safety of a machine learning-based automatic patient selection algorithm for stress-only myocardial perfusion SPECT

BackgroundStress-only myocardial perfusion imaging (MPI) markedly reduces radiation dose, scanning time, and cost. We developed an automated clinical algorithm to safely cancel unnecessary rest imaging with high sensitivity for obstructive coronary artery disease (CAD). Methods and ResultsPatients without known CAD undergoing both MPI and invasive coronary angiography from REFINE SPECT were studied. A machine learning score (MLS) for prediction of obstructive CAD was generated using stress-only MPI and pre-test clinical variables. An MLS threshold with a pre-defined sensitivity of 95% was applied to the automated patient selection algorithm. Obstructive CAD was present in 1309/2079 (63%) patients. MLS had higher area under the receiver operator characteristic curve (AUC) for prediction of CAD than reader diagnosis and TPD (0.84 vs 0.70 vs 0.78, P < .01). An MLS threshold of 0.29 had superior sensitivity than reader diagnosis and TPD for obstructive CAD (95% vs 87% vs 87%, P < .01) and high-risk CAD, defined as stenosis of the left main, proximal left anterior descending, or triple-vessel CAD (sensitivity 96% vs 89% vs 90%, P < .01). ConclusionsThe MLS is highly sensitive for prediction of both obstructive and high-risk CAD from stress-only MPI and can be applied to a stress-first protocol for automatic cancellation of unnecessary rest imaging.

Implications of transient ischemic dilatation and impaired left ventricular ejection fraction reserve in patients with normal stress myocardial perfusion imaging and elevated coronary artery calcium.

Guidelines recommend stress only (SO) myocardial perfusion imaging (MPI) without follow-up rest imaging if perfusion and left ventricular ejection fraction (LVEF) are normal. However additional rest imaging may show transient ischaemic dilation (TID) and/or impaired LVEF reserve (iLVEFr) suggestive of 'balanced ischemia'. Concurrent coronary artery calcium (CAC) scoring helps to identify subclinical atherosclerosis. The safety of SO MPI when CAC is elevated is unclear. We aim to assess the incidence and outcomes of TID and iLVEFr amongst stress/rest MPIs with normal SO images and elevated CAC. Retrospective analysis of normal stress/rest MPIs performed between 1 March 2016 to 31 January 2017 with concurrently measured CAC >300. Cases were stratified by presence of TID and/or iLVEFr. Major adverse cardiac events (MACE, defined as cardiac death, non-fatal myocardial infarction and revascularization) within 24 months were compared. There were 230 cases included of which 43 (18.7%) had TID and/or iLVEFr. Presence of TID and/or iLVEFr was associated with higher 24-month MACE (23.3 vs. 8.6%, p = 0.013), driven by more elective revascularizations (18.6 vs. 4.3%, p = 0.001). Cardiac death and non-fatal myocardial infarction rates were similar. TID and/or iLVEFr significantly predicted overall MACE after multivariate analysis (OR 2.933 [1.214 - 7.087], p = 0.017). TID and/or iLVEFr is seen in the minority of normal stress MPI with elevated CAC, and is associated with higher 24-month MACE, driven by higher elective revascularizations. Overall cardiac death and non-fatal myocardial infarction rates were low and not significantly different between both groups.

Stress only myocardial perfusion imaging - comparison of hospitalized and outpatient patients

Abstract Funding Acknowledgements Type of funding sources: None. Background In selected patients, stress-only myocardial perfusion imaging (MPI) has been proposed as an alternative to rest-stress MPI to reduce radiation exposure and enhance laboratory efficiency. The use of attenuation correction improves the diagnostic accuracy of stress-only imaging. However, criteria for selecting appropriate patients for stress-first imaging protocol are not uniform. There is limited data about stress-only MPI in hospitalized patients. The purpose of this study was to compare the proportion of suitable hospitalized and outpatient patients with normal MPI on a routine two-day protocol for stress-only MPI. Methods In a retrospective longitudinal cohort study, stress scintigrams (with and without attenuation correction) of consecutive hospitalized and outpatient patients who underwent MPI at our department by a routine two-day protocol and had a normal MPI were visually and semi-quantitatively re-examined. Patients with summed stress score 0 or 1 were considered as candidates for stress-only MPI. We also obtained data on the patients" clinical characteristics and their treatment. Results We studied 178 patients (mean age 68.8 ± 13.4 years, 89 hospitalized, 89 outpatient patients, 55.6 % female). Hospitalized patients were significantly older than outpatient participants (72.4 ± 13.0 vs. 65 ± 12.9 years, p &amp;lt; 0.001) with no significant differences in risk factors and clinical characteristics. Proportion of inpatients and outpatients suitable for stress-only MPI with and without attenuation correction is shown on Figure 1. There was no significant difference in stress-only MPI with and without attenuation correction between hospitalized and outpatient patients (Figure 1). 9.1% of patients in whom stress only MPI was possible had known coronary artery disease, whereas it was present in 25.0% of patients in whom stress-only MPI was not possible (p = 0.004). By using attenuation correction stress-only MPI could be performed in 54% of patients without known coronary artery disease. There was no difference between hospitalized patients and outpatients (52% vs. 56%, p = 0.700). Absence of coronary artery disease turned out as the only independent prognostic factor for application of stress-only MPI (odds ratio 3.433, 95% confidence interval 1.44-8.17, p = 0.003). There was no influence of hospitalization on the application of stress-only MPI. Conclusions When we choose the right patients (especially those without a known coronary artery disease) and use modern cameras that enable attenuation correction, we can perform stress-only MPI in 50% of patients with a normal MPI result. The same approach can be used for outpatients and inpatients.

Head-to-head comparison of diagnostic accuracy of stress-only myocardial perfusion imaging with conventional and cadmium-zinc telluride single-photon emission computed tomography in women with suspected coronary artery disease

BackgroundBreast attenuation may impact the diagnostic accuracy of stress myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT). We compared the performance of conventional (C)-SPECT and cadmium-zinc-telluride (CZT)-SPECT systems in women with low-intermediate likelihood of coronary artery disease (CAD). Methods and ResultsA total of 109 consecutive women underwent stress-optional rest MPI by both C-SPECT and CZT-SPECT. In the overall study population, a weak albeit significant correlation between total perfusion defect (TPD) measured by C-SPECT and CZT-SPECT was observed (r = 0.38, P < .001) and at Bland-Altman analysis the mean difference in TPD (C-SPECT minus CZT-SPECT) was 2.40% (P < .001). Overall concordance of semi-quantitative diagnostic performance between C-SPECT and CZT-SPECT was observed in 52 (48%) women with a κ value of 0.09. Normalcy rate was significantly higher using CZT-SPECT compared to C-SPECT (P < .001). Machine learning analysis performed through the implementation of J48 algorithm proved that CZT-SPECT has higher sensitivity, specificity, and accuracy than C-SPECT. ConclusionsIn women with low-intermediate likelihood of CAD, there is a poor concordance of diagnostic performance between C-SPECT and CZT-SPECT, and CZT-SPECT allows better normalcy rate detection compared to C-SPECT.

The prognostic significance of stress-only myocardial perfusion scan: A 5 year observational study.

Stress-only myocardial perfusion imaging protocol has a prognostic value similar to that of a stress-rest protocol. The aim of the study was to assess stress myocardial perfusion by gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (GSMPI) in patients who had a normal stress-only study 4.9 years (mean time) before and assess the possible influence of various factors on the results. Three hundred and forty patients who had a normal stress-only study in the past, were reexamined with GSMPI after a mean period of 4.9 years. Thirty out of 340 patients (8.8%) had an ischemic result on stress and were therefore submitted to a rest study. Differences between normal and pathological results across levels of potential prognostic factors (age, gender, diabetes mellitus, dyslipidemia, arterial hypertension, smoking and family history), symptoms,left ventricular ejection fraction (LVEF) on ultrasound (U/S), coronary angiography and pre-test probability did not prove statistically significant. On multivariable analysis patients with the combination of family history, diabetes mellitus and hypertension had a 10.7 times higher risk of a pathological scan than the patients without. The information delivered by stress-only GSMPI proved to be a prognostically reliable method for follow-up of low and intermediate pretest probability coronary artery disease (CAD) patients. The 91.2% of the patients with an initial normal stress-only GSMPI had a repeat normal stress-only GSMPI after a mean period of 4.9 years. The combination of family history, diabetes mellitus and hypertension increases the risk of a pathological scan significantly.

Diagnostic accuracy of stress-only myocardial perfusion SPECT improved by deep learning.

Deep convolutional neural networks (CNN) for single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has been used to improve the diagnostic accuracy of coronary artery disease (CAD). This study was to design and evaluate a deep learning (DL) approach to automatic diagnosis of myocardial perfusion abnormalities from stress-only MPI. The new DL approach developed for this study was compared to a conventional quantitative perfusion defect size (DS) method. A total of 37,243 patients (51.5% males) undergone stress 99mTc-Tetrofosmin or 99mTc-Sestamibi MPI were selected retrospectively from Yale New Haven Hospital. Patients were dichotomized as studies with normal (75.4%) or abnormal (24.6%) myocardial perfusion based on final diagnoses of clinical nuclear cardiologists. Stress myocardial perfusion defect size was calculated using Yale quantitative analytic software. A deep CNN was trained using the circumferential count profile maps derived from SPECT MPI and was evaluated for the diagnosis of perfusion abnormality with a 5-fold cross-validation approach. In each fold, 27,933, 1862 and 7448 patients were used as training, validation and testing datasets, respectively. The area under the receiver-operating characteristic curve (AUC) was calculated and analyzed for all patients as well as for the eight sub-groups classified based on patient genders, quantitative algorithms, radioactive tracers and SPECT cameras. The AUC value resulted from the DL method was significantly higher than that from the DS method (0.872 ± 0.002 vs. 0.838 ± 0.003, p < 0.01). Across the eight sub-groups, the DL method provided more consistent AUC values in terms of smaller standard deviation and higher diagnostic accuracy and specificity, but slightly lower sensitivity than the DS method (AUC: 0.865 ± 0.010 vs. 0.838 ± 0.019, Accuracy: 82.7% ± 2.5% vs. 78.5% ± 3.6%, Specificity: 84.9% ± 3.7% vs. 77.5% ± 6.5%, Sensitivity: 74.4% ± 4.2% vs. 79.8% ± 5.8%). The incorporation of deep learning for stress-only MPI has a considerable potential to improve the diagnostic accuracy and consistency in the detection of myocardial perfusion abnormalities.

Long-term prognostic value of low-dose normal stress-only myocardial perfusion imaging by wide beam reconstruction: A competing risk analysis

BackgroundA normal stress myocardial perfusion single-photon emission computed tomography (MPS) is associated with a good clinical outcome. New iterative algorithms, such as wide beam reconstruction (WBR), which improve image interpretation with half-dose or half-time acquisition, have been proposed for cardiac MPS. The aim of this study was to assess the long-term predictive value of a low-dose normal stress-only MPS with WBR using conventional Anger camera in patients with known or suspected coronary artery disease (CAD). Methods and ResultsA total of 2106 patients with known or suspected CAD and normal perfusion at half-dose stress-only MPS protocol were followed for a mean of 6.6 ± 2.7 years. MPS data were reconstructed with WBR iterative algorithm. End-point events were cardiac death or nonfatal myocardial infarction. Noncardiac death was considered the competing event. During follow-up, 149 cardiac events occurred with an annualized event rate of 1.2%. Independent predictors of cardiac events at Cox analysis were age, male gender, diabetes mellitus, previous myocardial infarction and the need for pharmacologic stress testing. At Fine-Gray analysis the cumulative incidence of cardiac events progressively increases with age and in the presence of diabetes for any combination of gender and stress type. Survival tree analysis confirmed that long-term prognosis considerably varies according of risk factors profile. ConclusionsLow-dose normal stress-only WBR MPS has a reliable long-term prognostic value in patients with suspected or known CAD. This finding supports the introduction of such a method into clinical practice with a consistent dose optimization in the interest of patients and exposed staff.

Application of stress-only myocardial perfusion imaging.

Single-photon emission computed tomography myocardial perfusion study is usually a sequence of stress and rest part. In case of a normal stress study rest part can be given up. The objective of this study was to examine factors affecting concordance of results of stress-only (SO) and stress-rest (SR) studies. SO and SR studies without and with attenuation correction (AC) of 212 selected patients (without cardiomyopathy, history of myocardial infarction or coronary artery bypass grafting) were analyzed visually. Influence of percutaneous coronary intervention (PCI) in the past, type of stress (physical/pharmacological) and application of AC (in form of combined method of non-corrected and corrected images - CM), patient body mass index (BMI) and gender on concordance rates of SO and SR studies were examined. Neither a history of PCI, nor a type of stress affected concordance rate. AC (in form of CM) improved concordance rate significantly, from 60% to 68% (p = 0.018). Patient BMI affected concordance rates - 72% in non-obese and 59% in obese patients (p = 0.05). In the whole group, risk of overlooking patients with abnormal perfusion in SO study was small (< 2%), but it grew significantly with patient BMI. Rest study was necessary in about 20% of non-obese and in about 50% of obese patients. MPS can be limited to stress part in appropriately selected, especially non-obese, patients provided that AC is applied, due to a low risk of overlooking patients with abnormal perfusion. In case of obese patients, careful analysis of exercise images for their normality is particularly important.

Comparative efficiency of exercise stress testing with and without stress-only myocardial perfusion imaging in patients with low-risk chest pain

ObjectivesTo compare major adverse cardiac event (MACE), downstream resource utilization, and direct cost of care for low-risk chest pain patients observed in the clinical decision unit (CDU) with exercise treadmill testing (ETT) and with stress-only myocardial perfusion imaging (sMPI). BackgroundCDUs are poised to increase efficiency and resource utilization. However, the optimal testing strategy that would assure favorable outcomes while decreasing cost is not defined. Methods1016 subjects from 2 locations were propensity score-matched (PSM) by age, gender, pre-test likelihood, Duke treadmill score, and test results. Outcomes were length of stay >24 hours, MACE (acute coronary syndrome, revascularization, cardiac death), downstream resource use (admission for chest pain, repeat testing, angiography), and mean direct cost per patient. ResultsPSM yielded 680 patients (340 matches). 98% of all tests were normal. 96.6% of patients were discharged from the CDU within 24 hours but twice as many exceeded 24 hours in the sMPI group. There were no cardiac deaths. MACE rate was 1.47% at 72 hours and 1% at 1 year. Downstream resource use was 4.82% at 72 hours, and 7.69% at 1 year. The sMPI group was event-free longer than the ETT group reflecting less repeat testing. The mean direct cost was 30% higher for sMPI ($3168.70) vs. ETT ($2226.96). ConclusionLow-risk chest pain patients in the observation unit had low MACE rate, not different for ETT vs. sMPI. The majority of ETT and sMPI tests were normal. The sMPI reduced additional testing, but resulted in greater expense and longer stay.

Current Practices in Myocardial Perfusion Scintigraphy in Brazil and Adherence to the IAEA Recommendations: Results of a Cross-Sectional Study.

BackgroundData on the current situation of nuclear medicine practices in cardiology in Brazil are scarce. The International Atomic Energy Agency (IAEA) has recommended eight "good practices" to minimize patients' ionizing radiation exposure during myocardial perfusion scintigraphy (MPS).ObjectivesTo assess the adoption of the eight good practices in MPS in Brazil.MethodsCross-sectional study with data obtained by use of a questionnaire. All hypothesis tests performed considered a significance level of 5%.ResultsWe observed that 100% of the nuclear medicine services (NMS) assessed do not use thallium-201 as the preferred protocol. Regarding the use of technetium-99m, 57% of the NMS administer activities above the threshold recommended by the IAEA (36 mCi) or achieve an effective dose greater than 15 millisievert (mSv). The abbreviated stress-only myocardial perfusion imaging is not employed by 94% of the NMS; thus, only 19% count on strategies to reduce the radioactive doses. Approximately 52% of the NMS reported always performing dose adjustment for patient's weight, while 35% administer poorly calculated doses in the one-day protocol.ConclusionA considerable number of NMS in Brazil have not adopted at least six practices recommended by the IAEA. Despite the difficulties found in nuclear practice in some Brazilian regions, almost all obstacles observed can be overcome with no cost increase, emphasizing the importance of developing strategies for adopting "good practices" when performing MPS.

Value of attenuation correction in stress-only myocardial perfusion imaging using CZT-SPECT

BackgroundAttenuation correction (AC) improves the diagnostic outcome of stress-only myocardial perfusion imaging (MPI) using conventional SPECT. Our aim was to determine the value of AC using a cadmium zinc telluride-based (CZT)-SPECT camera. Methods and resultsWe retrospectively included 107 consecutive patients who underwent stress-optional rest MPI CZT-SPECT/CT. Next, we created three types of images for each patient; (1) only displaying reconstructed data without the CT-based AC (NC), (2) only displaying AC, and (3) with both NC and AC (NC + AC). Next, two experienced physicians visually interpreted these 321 randomized images as normal, equivocal, or abnormal. Image outcome was compared with all hard events over a mean follow-up time of 47.7 ± 9.8 months. The percentage of images interpreted as normal increased from 45% using the NC images to 72% using AC and to 67% using NC + AC images (P < .001). Hard event hazard ratios for images interpreted as normal were not different between using NC and AC (1.01, P = .99), or NC and NC + AC images (0.97, P = .97). ConclusionsAC lowers the need for additional rest imaging in stress-first MPI using CZT-SPECT, while long-term patient outcome remained identical. Use of AC reduces the need for additional rest imaging, decreasing the mean effective dose by up to 1.2 mSv.

Combining stress-only myocardial perfusion imaging with coronary calcium scanning as a new paradigm for initial patient work-up: An exploratory analysis

BackgroundWe conducted an exploratory analysis to test whether the addition of a CAC scan can increase the applicability of stress-only SPECT-MPI. MethodsWe studied 162 patients referred for rest/stress SPECT-MPI who underwent a CAC scan. Each scan was interpreted by two readers in stepwise fashion: stress-only images; addition of clinical data; and addition of CAC data. At each step, the reader was asked if rest SPECT-MPI was necessary. ResultsStress-only images were interpreted as normal in 62, probably normal in 42, equivocal in 15, probably abnormal in 5, and definitely abnormal in 38 patients. Rest SPECT-MPI imaging was considered necessary, in 0% of normal studies, but in 88% of probably normal studies, and 100% of those with equivocal/abnormal studies. Addition of the clinical data did not materially change this decision. Additional consideration of the CAC scan results did not influence the deemed lack of need for a rest SPECT-MPI with normal SPECT-MPI or the necessity of rest SPECT-MPI with abnormal SPECT-MPI. However, the CAC scan reduced the deemed need for a rest SPECT-MPI in 72% with a probably normal, 47% with an equivocal, and 40% of those with a probably abnormal SPECT-MPI. ConclusionsOur exploratory analysis indicates that addition of a CAC scan to stress SPECT-MPI tends to diminish experienced readers’ deemed need to perform rest SPECT-MPI studies among patients with probably normal or borderline stress-only SPECT-MPI studies. Thus, further study appears warranted to assess the utility of using CAC scanning as a means for increasing the percent of SPECT-MPI studies that can be performed as stress-only studies.

Stress-only SPECT myocardial perfusion imaging: A review

Myocardial perfusion imaging (MPI) has enjoyed considerable success for decades due to its diagnostic accuracy and wealth of prognostic data. Despite this success several limitations such as lengthy protocols and radiation exposure remain. Advancements to address these shortcomings include abbreviated stress-only MPI (SO MPI) protocols, PET and both hardware and software methods to reduce radiation exposure and time. SO MPI has advantages in protocol time and radiation reduction with a wealth of supporting data in terms of diagnostic validity and prognostic value. Newer technologies such as attenuation correction, and advanced camera technologies have enabled SO MPI to be more efficient in reducing the time of acquisition and radiation dose and improving accuracy. This review examines the literature available, regarding accuracy, patient outcomes, implementation strategies, and newer developments associated with SO MPI.

Abstract 159: Evaluation of Downstream Utilization Following Stress-only versus Rest-Stress Myocardial Perfusion Imaging

Background: Current evidence and guidelines in nuclear cardiology support the use of stress-only myocardial perfusion imaging (SO-MPI), without rest imaging, to decrease radiation dose to the patient. We sought to determine the downstream utilization of cardiac procedures in patients undergoing SO-MPI in comparison to those undergoing rest-stress myocardial perfusion imaging (RS-MPI). Demonstration of the decreased need for cardiac procedures following SO-MPI would increase the confidence of interpreting nuclear cardiologists and referring physicians. Methods: We retrospectively analyzed the nuclear cardiology database at Allegheny General Hospital for patients undergoing stress testing with MPI from Jan 2010 to June 2011. Selection criteria for SO-MPI in our laboratory, includes no prior history of revascularization and low pre-test probability of coronary artery disease (CAD) based on symptoms and risk factors. We analyzed the rate of follow-up cardiac catherizations and repeat stress testing upto12 months after the index stress MPI. We compared the rate of procedure utilization following SO-MPI and RS-MPI. Results: A total of 5269 stress tests were performed during the enrollment period, of which 829 (16%) underwent SO-MPI, and the remainder (n=4440, 84%) had RS-MPI. Abnormal MPI was more likely in patients undergoing RS-MPI vs SO-MPI (525 vs 5; p&lt;0.05). Patients undergoing RS-MPI were more likely to have a follow-up procedure compared to those undergoing SO-MPI (odds ratio 2.5; p&lt;0.0001). Specifically the rate of cardiac catherization (565/4440; 13% in RS-MPI vs 27/829; 3%in SO-MPI p&lt;0.05) and the rate of repeat stress testing (177/4440; 4% in RS-MPI vs 15/829; 1.8% in SO-MPI, p&lt;0.05) were significantly higher in the RS-MPI group. Among patients undergoing SO-MPI, rate of cardiac catherization was significantly higher in patients having follow-up rest images compared to those that did not (odds ratio: 12.5, p&lt;0.001). There were 6 revascularizations in the SO-MPI group in the follow-up period of which 5 occurred in those with abnormal MPI and 1 occurred in a patient with normal SO-MPI but in the setting of an acute infarct. Conclusions: Downstream procedure utilization following a SO-MPI strategy is low. This complements the low mortality rate noted in this population by prior studies. It further confirms that the current selection criteria for SO-MPI is appropriate as most patients require only one image and do not need additional testing. In patients with low-intermediate pretest probability for CAD that are referred for MPI, SO-MPI with limited use of rest imaging can facilitate throughput, reduce patient radiation dose and is associated with appropriately low downstream utilization.

COMPARATIVE EFFICIENCY OF CORONARY CT ANGIOGRAPHY, MYOCARDIAL PERFUSION IMAGING AND EXERCISE TREADMILL TESTING IN OBSERVATION CARE OF PATIENTS WITH CHEST PAIN

The purpose of this study was to compare downstream resource use in patients with chest pain receiving observation care after an index exercise treadmill test (ETT), stress-only myocardial perfusion imaging (sMPI), and computer tomography angiography (CTA). Observation care for low-risk patients is

Reclassification of Cardiovascular Risk in Patients With Normal Myocardial Perfusion Imaging Using Heart Rate Response to Vasodilator Stress

Previous studies have shown that patients with normal vasodilator myocardial perfusion imaging (MPI) findings remain at a greater risk of future cardiac events than patients with normal exercise MPI findings. The aim was to assess improvement in risk classification provided by the heart rate response (HRR) in patients with normal vasodilator MPI findings when added to traditional risk stratification. We retrospectively studied 2,000 patients with normal regadenoson or adenosine MPI findings. Risk stratification was performed using Adult Treatment Panel III framework. Patients were stratified by HRR (percentage of increase from baseline) into tertiles specific to each vasodilator. All-cause mortality and cardiac death/nonfatal myocardial infarction (MI) ≤2 years from the index MPI were recorded. During follow-up, 11.8% patients died and 2.7% patients experienced cardiac death/nonfatal MI in the adenosine and regadenoson groups, respectively. The patients who died had a greater Framingham risk score (12 ± 4 vs 11 ± 4, p= 0.009) and lower HRR (22± 16 vs 32 ± 21, p <0.0001). In an adjusted Cox model, the lowest tertile HRR was associated with an increased risk of mortality (hazard ratio 2.1) and cardiac death/nonfatal MI (hazard ratio 2.9; p <0.01). Patients in the highest HRR tertile, irrespective of the Adult Treatment Panel III category, were at low risk. When added to the Adult Treatment Panel III categories, the HRR resulted in net reclassification improvement in mortality of 18% and cardiac death/nonfatal MI of 22%. In conclusion, a blunted HRR to vasodilator stress was independently associated with an increased risk of cardiac events and overall mortality in patients with normal vasodilator MPI findings. The HRR correctly reclassified a substantial proportion of these patients in addition to the traditional risk classification models and identified patients with normal vasodilator MPI findings, who had a truly low risk of events.

Stress-Only Tc-99m Myocardial Perfusion Imaging in an Emergency Department Chest Pain Unit

BackgroundStress-only myocardial perfusion imaging (MPI) saves time by eliminating rest imaging, which is important for emergency department (ED) throughput but has not been studied in an ED population. Study ObjectiveTo determine the prognosis of a normal stress-only MPI study compared to a normal rest-stress MPI and establish its effectiveness in an ED setting. MethodsAll patients evaluated in the ED over 6.5 years who underwent a stress-only technetium-99m gated MPI were compared to those who had a rest-stress study. All-cause mortality was determined using the Social Security Death Index. Survival was analyzed in patients with normal and abnormal MPI results. ResultsA total of 4145 studies (2340 stress-only, 1805 rest-stress) were performed. Patients’ average age was 57.9 years, 38.5% were male, and most had an intermediate or low pretest risk of coronary artery disease (87.7%). Average follow-up was 35.9 ± 20.9 months. In patients with normal perfusion, at 1 year of follow-up there were 11 deaths in the stress-only group (0.5% 1-year mortality), and 13 deaths in the rest-stress cohort (1.1% 1-year mortality). At the end of follow-up, the stress-only group had a lower all-cause mortality (p < 0.0001) and similar risk adjusted all-cause mortality (p = 0.10) than the rest-stress cohort. Patients with abnormal perfusion demonstrated the expected differential prognosis based on total perfusion deficits in both groups. ConclusionsA normal stress-only MPI study has a benign 1-year prognosis similar to a rest-stress study when performed in the ED. The ability to triage patients more rapidly and reduce radiation exposure represents an attractive alternative for low-risk patients.