Age- and Sex-Specific Myocardial Blood Flow Values in Patients Without Coronary Atherosclerosis on Rb-82 PET Myocardial Perfusion Imaging.

BACKGROUND: Quantitative myocardial blood flow (MBF) on positron-emission tomography myocardial perfusion imaging is a measure of the overall health of the coronary circulation. The ability to adequately augment blood flow, measured by myocardial blood flow reserve (MBFR), is associated with lower major adverse cardiovascular events and all-cause mortality. The age-specific ranges of MBFR in patients without demonstrable coronary artery disease have not been well established. We aimed to determine the effect of age and sex on MBF in a cohort of patients without demonstrable coronary artery disease. METHODS: Patients who underwent positron-emission tomography myocardial perfusion imaging studies from 2012 to 2022 on positron-emission tomography/computed tomography cameras were included if the summed stress score was 0, the coronary calcium score was 0, and the left ventricular ejection fraction was ≥50%. Those with known coronary artery disease, prior history of coronary intervention, diabetes, heart/kidney/liver transplant, cirrhosis, or chronic kidney disease stage IV+ were excluded. MBF was calculated using a net retention model (ImagenQ, Cardiovascular Imaging Technologies, Kansas City), and quantile regression models were developed to predict MBF. RESULTS: Among 2789 patients (age 59.9±13.0 years, 76.4% females), median rest MBF was 0.73 (0.60-0.91) mL/min·g, stress MBF was 1.72 (1.41-2.10) mL/min·g, and MBFR was 2.31 (1.96-2.74). Across all ages, males augmented MBF in response to vasodilator stress to a greater degree than females but achieved lower absolute stress MBF. Younger males in particular achieved a higher MBFR than their female counterparts, and this gap narrowed with increasing age. Predicted MBFR for a 20-year-old male was 3.18 and female was 2.50, while predicted MBFR for an 80-year-old male was 2.17 and female was 2.02. CONCLUSIONS: In patients without demonstrable coronary artery disease, MBFR is higher in younger males than younger females and decreases with age in both sexes. Age- and sex-specific MBFR may be important in risk prediction and guidance for revascularization and warrant further study.

Influence of Body Mass Index on Radiation Exposure Across Imaging Modalities in the Evaluation of Chest Pain.

BACKGROUND: Essential to a patient-centered approach to imaging individuals with chest pain is knowledge of differences in radiation effective dose across imaging modalities. Body mass index (BMI) is an important and underappreciated predictor of effective dose. This study evaluated the impact of BMI on estimated radiation exposure across imaging modalities. METHODS AND RESULTS: This was a retrospective analysis of patients with concern for cardiac ischemia undergoing positron emission tomography (PET)/computed tomography (CT), cadmium zinc telluride single-photon emission CT (SPECT) myocardial perfusion imaging, or coronary CT angiography (CCTA) using state-of-the-art imaging modalities and optimal radiation-sparing protocols. Radiation exposure was calculated across BMI categories based on established cardiac imaging-specific conversion factors. Among 9046 patients (mean±SD age, 64.3±13.1 years; 55% men; mean±SD BMI, 30.6±6.9 kg/m2), 4787 were imaged with PET/CT, 3092 were imaged with SPECT/CT, and 1167 were imaged with CCTA. Median (interquartile range) radiation effective doses were 4.4 (3.9-4.9) mSv for PET/CT, 4.9 (4.0-6.3) mSv for SPECT/CT, and 6.9 (4.0-11.2) mSv for CCTA. Patients at a BMI <20 kg/m2 had similar radiation effective dose with all 3 imaging modalities, whereas those with BMI ≥20 kg/m2 had the lowest effective dose with PET/CT. Radiation effective dose and variability increased dramatically with CCTA as BMI increased, and was 10 times higher in patients with BMI >45 kg/m2 compared with <20 kg/m2 (median, 26.9 versus 2.6 mSv). After multivariable adjustment, PET/CT offered the lowest effective dose, followed by SPECT/CT, and then CCTA (P<0.001). CONCLUSIONS: Although median radiation exposure is modest across state-of-the-art PET/CT, SPECT/CT, and CCTA systems using optimal radiation-sparing protocols, there are significant variations across modalities based on BMI. These data are important for making patient-centered decisions for ischemic testing.

Prevalence and Prognostic Importance of Abnormal Positron Emission Tomography Among Asymptomatic Patients With Diabetes Mellitus.

BACKGROUND: Ischemia and reduced global myocardial blood flow reserve (MBFR) are associated with high cardiovascular risk among symptomatic patients with diabetes mellitus (DM). OBJECTIVES: This study aimed to assess the prevalence and prognostic importance of silent ischemia and reduced MBFR among asymptomatic patients with DM. METHODS: This study included 2,730 consecutive patients with DM, without known coronary artery disease (CAD) or cardiomyopathy, who underwent rubidium-82 rest/stress positron emission tomography (PET) myocardial perfusion imaging (MPI) from 2010 to 2016. These patients were followed up for all-cause mortality (n = 461) for a median follow-up of 3 years. Patients were considered asymptomatic if neither chest pain nor dyspnea was elicited. Rates of ischemia, reduced MBFR, and coronary microvascular dysfunction on PET were assessed in both groups. Cox regression was used to define the independent association of abnormal MPI markers with mortality. RESULTS: One-quarter of patients with DM (23.7%; n = 647) were asymptomatic; ischemia was present in 30.5% (n = 197), reduced MBFR in 62.3% (n = 361), and coronary microvascular dysfunction in 32.7% (n = 200). In adjusted analyses, reduced MBFR (HR per 0.1 unit decrease in MBFR: 1.08 [95% CI: 1.03-1.12]; P = 0.001) and reduced ejection fraction (HR per 5% decrease: 1.10 [95% CI: 1.01-1.18]; P = 0.02) were independently prognostic of mortality among asymptomatic patients, but ischemia was not. This was comparable to DM patients with symptoms. Insulin use and older age were significant predictors of reduced MBFR among asymptomatic patients with DM. CONCLUSIONS: In both symptomatic and asymptomatic patients with DM, impairment in MBFR is common and associated with greater mortality risk.

Impact of Positron Emission Tomographic Myocardial Perfusion Imaging on Patient Selection for Revascularization.

BACKGROUND: Positron emission tomography (PET) myocardial perfusion imaging (MPI) quantifies left ventricular ejection fraction (LVEF) at peak stress. PET LVEF reserve (LVEF-R = stress LVEF - rest LVEF) offers diagnostic and prognostic value. OBJECTIVES: The purpose of this study was to determine if PET LVEF-R identifies patients with survival benefit postrevascularization. METHODS: We followed 14,649 unique consecutive patients undergoing 82Rb rest/stress PET MPI from January 2010 to January 2016 (excluding known cardiomyopathy). Adjusted Cox models were built to predict all-cause death, and the 3-way interaction of known coronary artery disease (CAD) (prior myocardial infarction/revascularization), LVEF-R, and 90-day revascularization was tested. RESULTS: Known CAD was present in 4,982 (34.0%). Ischemia was detected in 5,396 (36.8%; ≥10% in 1,909 [13%]). Mean LVEF-R was 4.2% ± 5.7%, and was ≤0, 1 to 5, and >5 in 3,349 (22.9%), 5,266 (35.9%), and 6,034 (41.2%). Over median follow-up of 3.4 years (IQR: 1.9-5.2 years), 1,324 (8.1%) had 90-day revascularization, and there were 2,192 (15.0%) deaths. In multivariable modeling, there was a significant 3-way interaction among known CAD, LVEF-R, and 90-day revascularization (P = 0.025), such that LVEF-R ≤0 identified patients with survival benefit with 90-day revascularization in those without prior CAD (interaction P = 0.005), independently beyond percent ischemia and myocardial flow reserve. Among patients with known CAD, LVEF-R was not prognostic of death (HR: 0.99; 95% CI: 0.98-1.02; P = 0.98). CONCLUSIONS: A lack of augmentation or drop in LVEF with vasodilator stress on PET MPI independently identifies patients who have better survival with revascularization within 90 days post-MPI compared with medical therapy, in absence of prior myocardial infarction or revascularization. Multiparametric assessment of ischemia with PET can optimize post-test management.

Coronary vascular dysfunction is associated with increased risk of death in patients with peripheral artery disease.

BACKGROUND: Peripheral artery disease (PAD) and coronary vascular dysfunction are common in patients with cardiometabolic disease. Neither the prevalence of coronary vascular dysfunction among patients with PAD nor the prognostic impact with these two conditions present together has been well studied. METHODS: Consecutive patients who underwent PET MPI were analyzed for presence of coronary vascular dysfunction [myocardial blood flow reserve (MBFR) < 2]. Cox regression was used to examine the association of reduced MBFR with mortality in patients with PAD, as well as the association of comorbid MBFR < 2 and PAD with all-cause death. RESULTS: Among 13,940 patients, 1936 (14%) had PAD, 7782 (56%) had MBFR < 2 and 1346 (10%) had both PAD and MBFR < 2. Reduced MBFR was very common (69.5%) and was associated with increased risk of all-cause death (HR 1.69, 95%CI 1.32, 2.16, p < 0.01) in patients with PAD. Patients with both PAD and MBFR < 2, and those with either PAD or reduced MBFR had increased risk of death compared to those with neither condition: PAD + MBFR < 2 [(HR 95%CI), 2.30; 1.97-2.68], PAD + MBFR ≥ 2 (1.37; (1.08-1.72), PAD - MBFR < 2 (1.98; 1.75-2.25), p < 0.001 for all). CONCLUSION: Coronary vascular dysfunction was common in patients with PAD and was associated with increased risk of death.

Association of Sex, Reduced Myocardial Flow Reserve, and Long-Term Mortality Across Spectrum of Atherosclerotic Disease.

BACKGROUND: Coronary vasomotor dysfunction (defined by reduced myocardial blood flow reserve [MBFR]) is associated with high cardiac risk in both men and women in absence of significant coexisting epicardial disease. Whether there is a sex-specific difference in prognostic value of reduced MBFR in patients with a greater burden of coexisting epicardial atherosclerotic disease is not well understood. OBJECTIVES: The purpose of this study was to examine the association of sex, MBFR, and mortality in consecutive patients with suspected or known coronary artery disease undergoing positron emission tomography myocardial perfusion imaging. METHODS: Unique consecutive patients undergoing rubidium (Rb)-82 rest/stress positron emission tomography myocardial perfusion imaging from 2010-2016 were followed for a median of 3.2 years. Multivariable Cox models were built to describe the interaction of sex and MBFR on all-cause and cardiac death for the overall population and stratified by extent of calcified atherosclerosis (none: coronary artery calcium score = 0, subclinical: coronary artery calcium >0, clinical: prior myocardial infarction/percutaneous coronary intervention) and abnormal perfusion (no significant obstructive disease: summed stress score = 0, 1%-9.9%, and ≥10%) at baseline. RESULTS: Among 12,594 patients, 52.8% were women. Compared with men, women had a lower prevalence of known coronary artery disease (16.5% vs 29.5%; P < 0.001) and were less likely to undergo revascularization after myocardial perfusion imaging (4.9% vs 9.7%; P < 0.001), but were more likely to have a reduced MBFR of <2 (56.2% vs 50.6%; P < 0.001). There were 1,699 (13.5%) all-cause and 490 (3.9%) cardiac deaths. In fully adjusted Cox models, reduced MBFR was independently associated with higher risk of death (HR per 0.1-U decrease: 1.09 [95% CI: 1.08-1.10]; P < 0.001), but female sex was not (HR: 0.95 [95% CI: 0.85-1.05]; P = 0.27). There was no significant interaction between sex and MBFR on death (P = 0.22) and cardiac death (P = 0.35) overall or in subgroups of patients with clinical, subclinical, and no atherosclerosis or across categories of perfusion abnormality at baseline. CONCLUSIONS: The association between reduced MBFR and higher risk of all-cause and cardiac death did not differ by sex, regardless of extent of coexisting atherosclerosis or perfusion abnormality.

Prognostic Relationship Between Coronary Artery Calcium Score, Perfusion Defects, and Myocardial Blood Flow Reserve in Patients With Suspected Coronary Artery Disease.

BACKGROUND: Coronary artery calcium score (CACS) is an anatomic measure of calcified atherosclerosis. Myocardial perfusion defects and reduced myocardial blood flow reserve (MBFR) are physiological measures of ischemia and coronary circulatory health. We aimed to assess the relative prognostic importance of MBFR, perfusion defects, and CACS in patients with suspected coronary artery disease. METHODS: A total of 5983 consecutive patients without known history of coronary artery disease or cardiomyopathy, who underwent a CACS and 82Rb positron emission tomography myocardial perfusion imaging between 2010 and 2016, were followed for all-cause death (n=785) over median of 3 years. Prognostic value was assessed using multivariable Cox regression models, and incremental risk discrimination for imaging variables was evaluated by comparing model c-indices after adjusting for clinical risk factors (RF). RESULTS: Mean age was 67.1 years, 60% were female, and 83% were symptomatic. CACS was 0 in 22%, abnormal perfusion in 19%, and MBFR <2 in 53.3%. When added to RF, the model with MBFR had the best fit (c=0.78, P<0.0001). Addition of CACS to model with RF and perfusion (c=0.77) offered modest improvement in discrimination over the model with RF and perfusion (c=0.76, P=0.02). Adding CACS to a model with RF, perfusion, and MBFR did not provide incremental prognostic value (c=0.785 for both, P=0.16). CACS and MBFR both had independent prognostic value in patients with normal and abnormal myocardial perfusion imaging. Even among patients with CACS of 0, MBFR <2 was present in 37.8%, being associated with higher risk of death (hazard ratio per 0.1↓, 1.10 [1.04-1.15]; P<0.001), but perfusion defects were not. CONCLUSIONS: Use of anatomic testing such as CACS of 0 to avoid myocardial perfusion imaging in symptomatic patients could lead to missing microvascular dysfunction in 4 out of 10 patients, a finding associated with a high mortality risk. Higher CACS was independently associated with the risk of death but did not provide incremental prognostic value over positron emission tomography with MBFR.

Relationship Between Myocardial Perfusion Imaging Abnormalities on Positron Emission Tomography and Anginal Symptoms, Functional Status, and Quality of Life.

BACKGROUND: Myocardial perfusion imaging (MPI) identifies abnormalities that occur early in the ischemic cascade leading to angina. Our aim was to study the association between ischemic measures on positron emission tomography MPI and patients' health status; their symptoms, function, and quality of life. METHODS: Health status was collected using the Seattle Angina Questionnaire (SAQ-7, 0-100, higher=better) and Rose Dyspnea Score (RDS) on 1515 outpatients with known or suspected coronary artery disease presenting for clinically indicated pharmacological 82Rb positron emission tomography MPI from July 2018 to July 2019. Adjusted multivariable ordinal regression models were used to assess the association between MPI findings of ischemia and the SAQ physical limitation, angina frequency, quality of life, summary score, and the RDS. RESULTS: The mean SAQ and RDS scores of the cohort (mean age 71.7 years, 55% male, 37.6% prior myocardial infarction or revascularization) were 73.8±28.6 (physical limitation), 87.4±21.7 (angina frequency), 79.0±26.1 (quality of life), 81.3±19.0 (summary score), and 2±2 (RDS). No perfusion, flow or function abnormalities were significantly associated with SAQ angina frequency scores. Low left ventricular ejection fraction reserve (≤0%), low global and regional myocardial blood flow reserve (<2) were independently associated with worse SAQ Physical Limitation score, SAQ summary score, and RDS (30% to 57% greater odds; all P≤0.01), but reversible perfusion defects were not. CONCLUSIONS: Impaired augmentation of left ventricular ejection fraction and myocardial blood flow with stress is associated with significant angina-associated functional limitation, health status, and dyspnea in patients who underwent positron emission tomography MPI, but not the frequency of their angina. Future studies should evaluate whether therapies that improve stress-induced abnormalities in systolic function and myocardial flow may improve patients' health status.

Relative Prognostic Significance of Positron Emission Tomography Myocardial Perfusion Imaging Markers in Cardiomyopathy.

BACKGROUND: Rubidium-82 positron emission tomography myocardial perfusion imaging provides measurements of perfusion, myocardial blood flow and reserve (MBFR), and changes in left ventricular ejection fraction (LVEF) at rest and peak stress. Although all of these variables are known to provide prognostic information, they have not been well studied in patients with heart failure due to reduced LVEF. METHODS: Between 2010 and 2016, 1255 consecutive unique patients with LVEF≤40% were included in this study who underwent rubidium-82 positron emission tomography myocardial perfusion imaging and did not have subsequent revascularization within 90 days. Perfusion assessment was scored semiquantitatively, and LVEF reserve (stress-rest LVEF) and global MBFR (stress/rest MBF) were quantified using automated software. Cox proportional hazards models adjusted for 14 clinical and 7 test characteristics were used to define the independent prognostic significance of MBFR on all-cause mortality. RESULTS: Of 1255 patients followed for a mean of 3.2 years, 454 (36.2%) died. After adjusting for clinical variables, the magnitude of fixed and reversible perfusion defects was prognostic of death (P=0.02 and 0.01, respectively), while the rest LVEF was not (P=0.18). The addition of LVEF reserve did not add any incremental value, while the addition of MBFR revealed incremental prognostic value (hazard ratio per 0.1 unit decrease in MBFR=1.08 [95% CI, 1.05-1.11], P<0.001) with fixed and reversible defects becoming nonsignificant (P=0.07 and 0.29, respectively). There was no interaction between MBFR and cause of cardiomyopathy (ischemic versus nonischemic). CONCLUSIONS: In patients with a known cardiomyopathy who did not require early revascularization, reduced MBFR as obtained by positron emission tomography myocardial perfusion imaging is associated with all-cause mortality while other positron emission tomography myocardial perfusion imaging measures were not.

Stress myocardial perfusion imaging in patients presenting with syncope: Comparison of PET vs. SPECT.

BACKGROUND: The role of myocardial perfusion imaging (MPI) in patients with suspected coronary artery disease (CAD) presenting with syncope is controversial. We aimed to determine diagnostic yield of MPI for evaluation of syncope in patients without known CAD, as a function of pre-test patient risk and test modality (PET vs SPECT). METHODS: Between 1/2010 and 12/2016, 1324 consecutive patients presenting with syncope without known CAD underwent MPI with PET (n = 640) or SPECT (n = 684). Rates of abnormal MPI (summed difference score (SDS) > 2 or left ventricular ejection fraction (LVEF) reserve ≤ 0 for PET and SDS > 2 or post-stress LVEF ≤ 45% for SPECT) were determined among patients stratified by pre-test risk. In patients who were referred for coronary angiography, diagnostic yield of obstructive CAD was calculated in the overall cohort as well as in a propensity-matched cohort compared to patients without syncope. RESULTS: Abnormal MPI was noted in 36.5% (201/551) of patients who had PET compared with 13.0% (87/671) who had SPECT (P < 0.001), which is largely related to higher comorbidity burden and greater pre-test CAD risk in the PET population. Among patients who had an abnormal MPI, 8.5% (47/551) with PET and 0.7% (5/671) with SPECT were found to have obstructive CAD if referred for coronary angiography. Patients at intermediate-high pre-test risk had a higher proportion of abnormal MPIs and obstructive CAD as compared to those at low risk in both the PET and SPECT cohorts. The rate of abnormal testing and diagnostic yield of PET MPI was similar and proportionate to pre-test likelihood among matched patients with and without syncope. CONCLUSIONS: Among patients referred for PET MPI with syncope at an intermediate-high pre-test CAD risk, 1 in 3 had an abnormal MPI and 1 in 10 had obstructive CAD. The value of MPI was related to pre-test risk as opposed to the presence of syncope, and MPI testing with PET or SPECT in the low-risk population was low value.

Technetium pyrophosphate nuclear scintigraphy for cardiac amyloidosis: Imaging at 1 vs 3 hours and planar vs SPECT/CT.

BACKGROUND: Multi-societal consensus recommendations endorse both planar and single photon emission tomographic (SPECT) image acquisitions for the evaluation of cardiac amyloidosis. However, the correlation between planar and SPECT findings and the optimal timing of image acquisitions remain uncertain. METHODS: This is an analysis of 109 consecutive patients who underwent technetium pyrophosphate nuclear scintigraphy for the evaluation of cardiac amyloidosis. Patients were imaged at 1 and 3 hours after radiotracer injection using both planar and SPECT/CT, and the correlations between imaging protocols were compared. RESULTS: In the overall cohort (median age 77 years, 75% male), 33 patients had radiotracer localized to the myocardium on SPECT/CT images. There was strong correlation between 1- and 3-hour planar heart-to-contralateral lung ratios (mean difference 0.07, r = 0.94). However, there was discordance between planar image interpretation (based upon semiquantitative score and H/CL ratio) and myocardial localization of radiotracer on SPECT/CT in 17 patients (16%). The pattern of SPECT/CT uptake was identical at 1 and 3 hours in all cases (32 diffuse, 1 focal). CONCLUSION: These data support the recommendation that SPECT/CT should be obtained in addition to planar images when performing nuclear scintigraphy for the detection of cardiac amyloidosis. A 1-hour planar and SPECT/CT protocol appears optimal.

Myocardial blood flow reserve assessed by positron emission tomography myocardial perfusion imaging identifies patients with a survival benefit from early revascularization.

AIMS: Positron emission tomography (PET) myocardial perfusion imaging (MPI) can non-invasively measure myocardial blood flow reserve (MBFR). We aimed to examine whether MBFR identifies patients with a survival benefit after revascularization, helping to guide post-test management. METHODS AND RESULTS: We examined all-cause mortality in 12 594 consecutive patients undergoing Rb82 rest/stress PET MPI from January 2010 to December 2016, after excluding those with cardiomyopathy, prior coronary artery bypass surgery (CABG), and missing MBFR. Myocardial blood flow reserve was calculated as the ratio of stress to rest absolute myocardial blood flow. A Cox model adjusted for patient and test characteristics, early revascularization (percutaneous coronary intervention or CABG ≤90 days of MPI), and the interaction between MBFR and early revascularization was developed to identify predictors of all-cause mortality. After a median follow-up of 3.2 years, 897 patients (7.1%) underwent early revascularization and 1699 patients (13.5%) died. Ischaemia was present in 4051 (32.3%) patients, with 1413 (11.2%) having ≥10% ischaemia. Mean MBFR was 2.0 ± 1.3, with MBFR <1.8 in 4836 (38.5%). After multivariable adjustment, every 0.1 unit decrease in MBFR was associated with 9% greater hazard of all-cause death (hazard ratio 1.09, 95% confidence interval 1.08-1.10; P < 0.001). There was a significant interaction between MBFR and early revascularization (P < 0.001); such that patients with MBFR ≤1.8 had a survival benefit with early revascularization, regardless of type of revascularization or level of ischaemia. CONCLUSION: Myocardial blood flow reserve on PET MPI is associated with all-cause mortality and can identify patients who receive a survival benefit with early revascularization compared to medical therapy. This may be used to guide revascularization, and prospective validation is needed.

Extent of Myocardial Ischemia on Positron Emission Tomography and Survival Benefit With Early Revascularization.

BACKGROUND: Prior studies with single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) have shown a survival benefit with early revascularization in patients with >10% to 12.5% ischemic myocardium. The relationship among positron emission tomography (PET)-derived extent of ischemia, early revascularization, and survival is unknown. OBJECTIVES: The purpose of this study was to evaluate the association among percent ischemia on PET MPI, revascularization, and survival. METHODS: A total of 16,029 unique consecutive patients who were undergoing Rubidium-82 rest-stress PET MPI from 2010 to 2016 were included. Patients with known cardiomyopathy and nondiagnostic perfusion results were excluded. Percent ischemic myocardium was estimated from a 17-segment model. Propensity scoring was used to account for nonrandomized referral to early revascularization (90 days of PET). A Cox model was developed, adjusting for propensity scores for early revascularization and percent ischemia, and an interaction between ischemia and early revascularization was tested. RESULTS: Median follow-up was 3.7 years. Overall, 1,277 (8%) patients underwent early revascularization and 2,493 (15.6%) died (738 cardiac). Nearly 37% of patients (n = 5,902) had ischemia, with 13.5% (n = 2,160) having ≥10%. In propensity-adjusted analyses, there was a significant interaction between ischemia and early revascularization (p < 0.001 for all-cause and cardiac death), such that patients with greater ischemia had improved survival with early revascularization, with a potential ischemia threshold at 5% (upper limit 95% confidence interval at 10%). There was no differential association between ischemia and early revascularization on death based on history of known coronary artery disease (interaction p = 0.72). CONCLUSIONS: In a contemporary cohort of patients undergoing PET MPI, patients with greater ischemia had a survival benefit from early revascularization. On exploratory analyses, this threshold was lower than that previously reported for SPECT. These findings require future validation in prospective cohorts or trials.

Randomized Comparison of Clinical Effectiveness of Pharmacologic SPECT and PET MPI in Symptomatic CAD Patients.

OBJECTIVES: This study compared the clinical effectiveness of pharmacologic stress myocardial perfusion imaging (MPI) plus positron emission tomography (PET) with single-photon emission computed tomography (SPECT) in patients with known coronary artery disease (CAD) presenting with symptoms suggestive of ischemia. BACKGROUND: Although PET MPI has been shown to have higher diagnostic accuracy in detecting hemodynamically significant CAD than SPECT MPI, whether this impacts downstream management has not been formally evaluated in randomized trials. METHODS: This study consisted of a single-center trial in which patients with known CAD and suspected ischemia were randomized to undergo PET or attenuation-corrected SPECT MPI between June 2009 and September 2013. Post-test management was at the discretion of the referring physician, and patients were followed for 12 months. The primary endpoint was diagnostic failure, defined as unnecessary angiography (absence of ≥50% stenosis in ≥1 vessel) or additional noninvasive testing within 60 days of the MPI. Secondary endpoints were post-test escalation of antianginal therapy, referral for angiography, coronary revascularization, and health status at 3, 6, and 12 months. RESULTS: A total of 322 patients with an evaluable MPI were randomized (n = 161 in each group). At baseline, 88.8% of patients were receiving aspirin therapy, 76.7% were taking beta-blockers, and 77.3% were taking statin therapy. Diagnostic failure within 60 days occurred in only 7 patients (2.2%) (3 [1.9%] in the PET group and 4 [2.5%] in the SPECT group; p = 0.70). There were no significant differences between the 2 groups in subsequent rates of coronary angiography, coronary revascularization, or health status at 3, 6, and 12 months of follow-up (all p values ≥0.20); however, when subjects were stratified by findings on MPI in a post hoc analysis, those with high-risk MPI on PET testing had higher rates of angiography and revascularization on follow-up than those who had SPECT MPI, whereas those undergoing low-risk PET studies had lower rates of both procedures than those undergoing SPECT (interaction between randomized modality ∗high-risk MPI for 12-month catheterization [p = 0.001] and 12-month revascularization [p = 0.09]). CONCLUSIONS: In this contemporary cohort of symptomatic CAD patients who were optimally medically managed, there were no discernible differences in rates of diagnostic failure at 60 days, subsequent coronary angiography, revascularization, or patient health status at 1 year between patients evaluated by pharmacologic PET compared with those evaluated by SPECT MPI. Downstream invasive testing rates with PET MPI were more consistent with high-risk features than those with SPECT MPI. (Effectiveness Study of Single Photon Emission Computed Tomography [SPECT] Versus Positron Emission Tomography [PET] Myocardial Perfusion Imaging; NCT00976053).

Nonbacterial thrombotic endocarditis involving both the tricuspid and aortic valves.

A 71-year-old male presented after sudden onset of confusion and expressive aphasia. MRI head revealed multiple ischemic lesions consistent with cardio-embolic pathophysiology. A computed tomography angiography of lung showed peripheral pulmonary emboli. He underwent a transesophageal echocardiogram as a part of the stroke workup and was found to have vegetations on both aortic and tricuspid valves. The blood cultures did not show any growth, and the patient remained afebrile during the course of hospitalization. A diagnosis of nonbacterial thrombotic embolism was made, and he was discharged on anticoagulation therapy with subcutaneous low molecular heparin.