Positron Emission Tomography Myocardial Perfusion Imaging Research Articles

The impact of diabetes on the relationship of coronary artery disease and outcome: a study using multimodality imaging

BackgroundPatients with prediabetes or diabetes are at increased risk of developing cardiovascular disease and adverse outcomes. First-line coronary computed tomography angiography (CTA) followed by selective use of positron emission tomography (PET) myocardial perfusion imaging is a feasible strategy to diagnose and risk-stratify patients with suspected coronary artery disease (CAD). The aim of the present study was to study whether diabetes changes the relationship of CAD and long-term outcome.MethodsWe retrospectively identified consecutive symptomatic patients who underwent coronary CTA for suspected CAD. In patients with suspected obstructive CAD on CTA, myocardial ischemia was evaluated by 15O-water PET myocardial perfusion imaging. The relationship of the phenotype of CAD and long-term outcome in patients with no diabetes, prediabetes, or type 2 diabetes was investigated. A composite endpoint included all-cause mortality, myocardial infarction (MI), and unstable angina pectoris (UAP).ResultsA total of 1743 patients were included: 1214 (70%) non-diabetic, 259 (15%) prediabetic, and 270 (16%) type 2 diabetic patients. During 6.43 years of median follow-up, 164 adverse events occurred (106 deaths, 41 MIs, 17 UAPs). The prevalence of normal coronary arteries on CTA was highest in the non-diabetic patients (39%). The prevalence of hemodynamically significant CAD (abnormal perfusion) increased from 14% in non-diabetic patients to 20% in prediabetic and 27% in diabetic patients. The event rate was lowest in patients with normal coronary arteries and highest in patients with concomitant type 2 diabetes and hemodynamically significant CAD (annual event rate 0.2% vs. 4.7%). However, neither prediabetes nor diabetes were independent predictors of the composite adverse outcome after adjustment for the clinical risk factors and imaging findings.ConclusionsCoronary CTA followed by selective downstream use of PET myocardial perfusion imaging predicts long-term outcome similarly in non-diabetic and diabetic patients.

Characteristics and key differences between patient populations receiving imaging modalities for coronary artery disease diagnosis in the US

BackgroundThere are limited data on the impact of imaging modality selection for the assessment of coronary artery disease (CAD) risk on downstream resource utilisation. This study sought to identify differences between patient populations in the US undergoing stress echocardiography, single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), positron emission tomography (PET) MPI, and coronary computed tomography angiography (cCTA) for the assessment of CAD risk, and associated physician referral patterns.MethodsClaims and electronic health records data for 2.5 million US patients who received stress echocardiography, cCTA, SPECT MPI or PET MPI between January 2016 and March 2018, from the Decision Resources Group Real-World Evidence US Data Repository, were analysed. Patients were stratified into suspected and existing CAD cohorts, and further stratified by pre-test risk and presence and recency of interventions or acute cardiac events (within 1–2 years pre-index test). Linear and logistic regression were used to compare numeric and categorical variables.ResultsPhysicians were more likely to refer patients to standalone SPECT MPI (77%) and stress echocardiography (18%) than PET MPI (3%) and cCTA (2%). Overall, 43% of physicians referred more than 90% of their patients to standalone SPECT MPI. Just 3%, 1% and 1% of physicians referred more than 90% of their patients to stress echocardiography, PET MPI or cCTA. At the aggregated imaging level, patients who underwent stress echocardiography or cCTA had similar comorbidity profiles. Comorbidity profiles were also similar for patients who underwent SPECT MPI and PET MPI.ConclusionMost patients underwent SPECT MPI at the index date, with very few undergoing PET MPI or cCTA. Patients who underwent cCTA at the index date were more likely to undergo additional imaging tests compared with those who underwent other imaging modalities. Further evidence is needed to understand factors influencing imaging test selection across patient populations.

Myocardial perfusion imaging by 15O-H2O positron emission tomography predicts clinical revascularization procedures in symptomatic patients with previous coronary artery bypass graft.

We wanted to assess if 15O-H2O myocardial perfusion imaging (MPI) in a clinical setting can predict referral to coronary artery catheterization [coronary angiography (CAG)], execution of percutaneous coronary intervention (PCI), and post-PCI angina relief for patients with angina and previous coronary artery bypass graft (CABG). We analysed 172 symptomatic CABG patients referred for 15O-H2O positron emission tomography (PET) MPI at Aarhus University Hospital Department of Nuclear Medicine & PET Centre, of which five did not complete the scan. In total, 145 (87%) enrolled patients had an abnormal MPI. Of these, 86/145 (59%) underwent CAG within 3 months; however, no PET parameters predicted referral to CAG. During the CAG, 25/86 (29%) patients were revascularized by PCI. Relative flow reserve (RFR) (0.49 vs. 0.54 P = 0.03), vessel-specific myocardial blood flow (MBF) (1.53 vs. 1.88 mL/g/min, P < 0.01), and vessel-specific myocardial flow reserve (MFR) (1.73 vs. 2.13, P < 0.01) were significantly lower in patients revascularized by PCI. Receiver operating characteristic analysis of the vessel-specific parameters yielded optimal cutoffs of 1.36 mL/g/min (MBF) and 1.28 (MFR) to predict PCI. Angina relief was experienced by 18/24 (75%) of the patients who underwent PCI. Myocardial blood flow was an excellent predictor of angina relief on both a global [area under the curve (AUC) = 0.85, P < 0.01] and vessel-specific (AUC = 0.90, P < 0.01) level with optimal cutoff levels of 1.99 mL/g/min and 1.85 mL/g/min, respectively. For CABG patients, RFR, vessel-specific MBF, and vessel-specific MFR measured by 15O-H2O PET MPI predict whether subsequent CAG will result in PCI. Additionally, global and vessel-specific MBF values predict post-PCI angina relief.

Estimation of Microvascular Dysfunction by Using 13N-Ammonia Positron Emission Tomography with Quantitative Myocardial Blood Flow Analysis in Chronic Coronary Syndrome.

Although coronary artery disease (CAD) is characterized by epicardial atherosclerosis and microvascular disease, the importance of evaluating microvascular dysfunction has not been sufficiently recognized in clinical practice. We estimated microvascular disease severity by assessing hyperemic microvascular resistance (MVR), as determined by absolute quantification of myocardial blood flow (MBF) with 13N-ammonia positron emission tomography-myocardial perfusion imaging (PET-MPI). We retrospectively collected data for 23 CAD patients who underwent both stress/rest PET-MPI and invasive coronary angiography (CAG) with fractional flow reserve (FFR) measurement. Among 30 vessels for which FFR measurement was performed, 13 had a low FFR (FFR ≤0.75). For each patient, myocardial segments of a standard 17-segment model were assigned to the stenotic myocardial area perfused by the FFR-measured vessel and a reference normal-perfusion area based on PET-MPI and the coronary distribution on CAG. Hyperemic MVR was calculated by using the formula, hyperemic MVR = hyperemic mean blood pressure × FFR/hyperemic MBF of the stenotic vessel. A strong negative correlation was observed between hyperemic MVR and hyperemic MBF in the reference normal-perfusion area (R = -0.758, P<0.001). Microvascular disease severity in chronic CAD can be estimated by hyperemic MBF of the normal-perfusion area with 13N-ammonia PET-MPI.

Prognostic value of combined coronary CT angiography and myocardial perfusion imaging in women and men.

Combined anatomical and functional imaging enables detection of non-obstructive and obstructive coronary artery disease (CAD) as well as myocardial ischaemia. We evaluated sex differences in disease profile and outcomes after combined computed tomography angiography (CTA) and positron emission tomography (PET) perfusion imaging in patients with suspected obstructive CAD. We retrospectively evaluated 1948 patients (59% women) referred for coronary CTA due to suspected CAD during the years 2008-2016. Patients with a suspected obstructive lesion on coronary CTA (n = 657) underwent 15O-water PET to assess stress myocardial blood flow (MBF). During a mean follow-up of 6.8 years, 182 adverse events (all-cause death, myocardial infarction, or unstable angina) occurred. Women had more often normal coronary arteries (42% vs. 22%, P < 0.001) and less often abnormal stress MBF (9% vs. 28%, P < 0.001) than men. The annual adverse event rate was lower in women vs. men (1.2% vs. 1.7%, P = 0.02). Both in women and men, coronary calcification, non-obstructive CAD, and abnormal stress MBF were independent predictors of events. Abnormal stress MBF was associated with 5.0- and 5.6-fold adverse event rates in women and men, respectively. There was no interaction between sex and coronary calcification, non-obstructive CAD, or abnormal stress MBF in terms of predicting adverse events. Among patients evaluated for chronic chest pain, women have a lower prevalence of ischaemic CAD and a lower rate of adverse events. Combined coronary CTA and PET myocardial perfusion imaging predict outcomes equally in women and men.

Improved Performance of PET Myocardial Perfusion Imaging Compared to SPECT in the Evaluation of Suspected CAD.

Myocardial perfusion imaging (MPI) with single photon emission computed tomography (SPECT) has played a central role in the non-invasive evaluation of patients with obstructive coronary artery disease (CAD) for decades. In this review, we discuss the key differences and advantages of positron emission tomography (PET) MPI over SPECT MPI as it relates to the diagnosis, prognosis, as well as clinical decision-making in patients with suspected CAD. Stress-induced perfusion abnormalities on SPECT help estimate presence, extent, and location of ischemia and flow-limiting obstructive CAD, help with risk stratification, and serve as a gatekeeper to identify patients who will benefit from downstream revascularization versus medical management. Some of the major limitations of SPECT include soft-tissue attenuation artifacts, underestimation of ischemia due to reliance on relative perfusion assessment, and longer protocols with higher radiation dose when performed with traditional equipment. PET MPI addresses most of these limitations and offers better quality images, higher diagnostic accuracy along with shorter protocols and lower radiation dose to the patient. A special advantage of PET scanning lies in the ability to quantify absolute myocardial blood flow and assess true extent of epicardial involvement along with identifying non-obstructive phenotypes of CAD such as diffuse atherosclerosis and microvascular dysfunction. In addition, stress acquisition at/near peak stress with PET allows us to measure left ventricular ejection fraction reserve and myocardial blood flow reserve, which help with identifying patients at a higher risk of future cardiac events and optimally select candidates for revascularization. The several technical advantages of PET MPI position as a superior method to diagnose obstructive and non-obstructive phenotypes of ischemic heart disease affecting the entirety of the coronary circulation offer incremental value for risk stratification and guide post-test management strategy for patients with suspected CAD.

Advances in Digital PET Technology and Its Potential Impact on Myocardial Perfusion and Blood Flow Quantification.

In this review, we explore the development of digital PET scanners and describe the mechanism by which they work. We dive into some technical details on what differentiates a digital PET from a conventional PET scanner and how such differences lead to better imaging characteristics. Additionally, we summarize the available evidence on the improvements in the images acquired by digital PET as well as the remaining pitfalls. Finally, we report the comparative studies available on how digital PET compares to conventional PET, particularly in the quantification of coronary blood flow. The advent of digital PET offers high sensitivity and time-of-flight (TOF), which allow lower activity and scan times, with much less risk of detector saturation. This allows faster patient throughput, scanning more patients per generator, and acquiring more consistent image quality across patients. The higher sensitivity captures more of the potential artifacts, particularly motion-related ones, which presents a current challenge that still needs to be tackled. The digital silicon photomultiplier (SiPM) positron emission tomography (PET) machine has been an important development in the technological advancements of non-invasive nuclear cardiovascular imaging. It has enhanced the utility for PET myocardial perfusion imaging (MPI) and myocardial blood flow (MBF) quantification.

Incorporating coronary artery calcium scoring in the prediction of obstructive coronary artery disease with myocardial ischemia: a study with sequential use of coronary computed tomography angiography and positron emission tomography imaging

BackgroundAdditional strategies are needed to refine the referral for diagnostic testing of symptomatic patients with suspected coronary artery disease (CAD). We aimed to compare various models to predict hemodynamically obstructive CAD. Methods and resultsSymptomatic patients with suspected CAD who underwent coronary artery calcium scoring (CACS) and sequential coronary computed tomography angiography (CCTA) and [15O]H2O positron emission tomography (PET) myocardial perfusion imaging were analyzed. Obstructive CAD was defined as a suspected coronary artery stenosis on CCTA with myocardial ischemia on PET (absolute stress myocardial perfusion ≤ 2.4 mL/g/min in ≥ 1 segment). Three models were developed to predict obstructive CAD-induced myocardial ischemia using logistic regression analysis: (1) basic model: including age, sex and cardiac symptoms, (2) risk factor model: adding number of risk factors to the basic model, and (3) CACS model: adding CACS to the risk factor model. Model performance was evaluated using discriminatory ability with area under the receiver-operating characteristic curves (AUC). A total of 647 patients (mean age 62 ± 9 years, 45% men) underwent CACS and sequential CCTA and PET myocardial perfusion imaging. Obstructive CAD with myocardial ischemia on PET was present in 151 (23%) patients. CACS was independently associated with myocardial ischemia (P < .001). AUC for the discrimination of ischemia for the CACS model was superior over the basic model and risk factor model (P < .001). ConclusionsAdding CACS to the model including age, sex, cardiac symptoms and number of risk factors increases the accuracy to predict obstructive CAD with myocardial ischemia on PET in symptomatic patients with suspected CAD.

Abstract 11488: Comparative Effectiveness of PET and SPECT Myocardial Perfusion Imaging for Identification of Low-Risk Patients With Cardiometabolic Disease

Introduction: The epidemiology of coronary artery disease (CAD) has shifted, with increasing cardiometabolic (CM) disease and decreasing obstructive CAD in patients referred for myocardial perfusion imaging (MPI). Coronary microvascular dysfunction, defined as impaired coronary flow reserve (CFR) by positron emission tomography (PET), has emerged as a key mediator of risk. Our objective was to assess whether CFR provides additive value to identify low-risk CM disease patients compared with single-photon emission computed tomography (SPECT) MPI. Methods: We retrospectively studied patients with CM disease (obesity, diabetes, or chronic kidney disease (CKD) stage ≥3) and without known CAD referred for PET or SPECT MPI at our center from 2006 to 2020. Annualized all-cause and cardiac mortality was determined from death certificates, and propensity-matched low-risk PET and SPECT patients were compared using Poisson and Cox regression. Results: CM disease was prevalent in consecutive MPI referrals without CAD including obesity (N=8869), diabetes (N=4896) and CKD (N=3555), and higher among PET MPI (p &lt;0.001). Prevalence of summed stress score (SSS) &gt;3 reflecting obstructive CAD was low (12%, 15% and 16%). Conversely, prevalence of CFR &lt;2 was high (52%, 61% and 69%), reflecting impaired myocardial perfusion. In adjusted hazard analysis, normal MPI was associated with lower risk of all-cause and cardiac death (p &lt;0.001). Normal PET (SSS ≤3 and CFR &gt;2) was associated with lower all-cause death compared to normal SPECT (Figure, A). Normal PET and SPECT identified low-risk (&lt;1%/year cardiac death) patients with obesity and diabetes, however those with CKD remained moderate-risk (1-3%/year) (Figure, B). Conclusion: CM disease is common among patients without CAD referred for MPI. Normal PET and SPECT MPI identify a low-risk group for obesity and diabetes, but not CKD. PET with CFR has additive prognostic utility to identify low-risk individuals compared to SPECT.

Abstract 9874: Correlation of Left Ventricular Strain Derived From Rb-82 ECG-Gated PET Myocardial Perfusion Imaging vs 2D Echocardiography

Introduction: Global longitudinal strain (GLS) by two-dimensional (2D) transthoracic echocardiography (TTE) is a robust index for identifying early left ventricular (LV) myocardial dysfunction. Positron emission tomography (PET) myocardial perfusion imaging (MPI) is widely used in the assessment of ischemic heart disease (IHD) but has not been used for strain analysis. Hypothesis: Longitudinal, radial, and circumferential myocardial strain measures at rest and at pharmacologic stress by Rb-82 ECG-gated PET MPI are correlated to those measured by resting 2D TTE. Methods: We developed a novel PET MPI method to track the LV myocardium throughout the cardiac cycle processed in the Emory Cardiac Toolbox, to measure LV strain from longitudinal, radial, and circumferential direction at regadenoson-stress and at rest. We retrospectively identified 80 patients who underwent Rb-82 PET MPI and also had TTE with strain analysis within 3 months. The agreement between LV strain and LVEF derived from PET MPI and resting TTE was assessed with Bland-Altman analysis, Pearson’s correlation, and the concordance correlation coefficient (CCC). Results: PET MPI derived measurements of longitudinal (Figure 1A-1B: Bland-Altman analysis; 1C-1D: Pearson’s correlations), circumferential (Figure 1E-1F: Pearson’s correlations) and radial (Figure 1G-1H: Pearson’s correlations) strain measures at rest and stress were strongly correlated to resting TTE derived GLS (p&lt;.001). LVEF showed strong correlations at stress (0.83, p&lt;.001) and rest (0.80, p&lt;.001). Inter-observer agreements of PET MPI strain measures showed high correlation between 2 independent observers for all 3 directions (p&lt;.001). Conclusions: LV strain measures by PET MPI using a novel automated technique correlated strongly with GLS by TTE. PET MPI measures are highly reproducible. Strain by PET MPI should be investigated further to establish its value in routine clinical practice.

Improving Detection of CAD and Prognosis with PET/CT Quantitative Absolute Myocardial Blood Flow Measurements.

The purpose of this review is to provide an overview of the role of PET MPI in the detection of CAD, focussing on the added value of MBF for diagnosis and prognostication. Positron emission tomography (PET) myocardial perfusion imaging (MPI) is increasingly used for the risk stratification of patients with suspected or established coronary artery disease (CAD). PET MPI provides accurate and reproducible non-invasive quantification of myocardial blood flow (MBF) at rest and during hyperemia, providing incremental information over conventional myocardial perfusion alone. Inclusion of MBF in PET MPI interpretation improves both its sensitivity and specificity. Moreover, quantitative MBF measurements have repeatedly been shown to offer incremental and independent prognostic information over conventional clinical markers in a broad range of conditions, including in CAD. Quantitative MBF measurement is now an established and powerful tool enabling accurate risk stratification and guiding patients' management. The role of PET MPI and flow quantification in cardiac allograft vasculopathy (CAV), which represents a particular form of CAD, will also be reviewed.

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 &lt;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 &lt;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.

PET Myocardial Blood Flow for Post-transplant Surveillance and Cardiac Allograft Vasculopathy in Heart Transplant Recipients.

Cardiac allograft vasculopathy (CAV) is a late-occurring complication of heart transplantation significantly limiting overall graft survival. In the last few years, evidence has been growing about the use of positron emission tomography (PET) myocardial perfusion imaging with integrated myocardial blood flow (MBF) quantification in heart transplant recipients. Multiple studies have demonstrated that PET MBF assessment can be utilized to establish the diagnosis of CAV noninvasively and can be employed for prognostication. PET MBF quantification has also helped to define the link between transplant rejection and CAV. In addition, limited data suggests that PET MBF quantification can be used in heart transplant patients for serial monitoring of CAV. PET myocardial perfusion imaging integrating MBF quantification shows great promise for the evaluation of CAV with good diagnostic and prognostic performance.

Long-standing persistent atrial fibrillation with low coronary flow reserve is associated with unnecessary coronary angiography

Abstract Background/Introduction Atrial fibrillation (AF) is associated with an increased risk of myocardial infarction. Myocardial perfusion imaging (MPI) is well-established for the diagnosis of coronary artery disease (CAD) and risk-stratification in sinus rhythm (SR) patients. Purpose The aim of this study was to determine the impact of AF and coronary flow reserve (CFR) on revascularization in patients undergoing positron emission tomography (PET) MPI. Methods 680 patients without a known history of CAD were included. 226 paroxysmal AF (PAF) and 114 long-standing persistent AF (LSPAF) patients were identified from a single-center prospective PET MPI registry and propensity matched in a 1:1 ratio to SR patients. The main indications for PET MPI were chest pain and dyspnea. Follow-up was obtained for downstream referral for invasive coronary angiography (CAG) and the occurrence of myocardial infarction (MI) or coronary revascularization. Results Compared with PAF, LSPAF patients were older (p=0.011) and more frequently male (p=0.031), with no significant differences in prior medical history and cardiac risk factors. The number of abnormal scans (infarction or ischemia) did not differ significantly between SR and AF, respectively 22.1% and 18.5% (p=0.253). The frequency of downstream CAG was comparable between the groups (p=0.298), with a significantly higher yield of obstructive CAD in the SR group as compared to PAF and LSPAF groups (63% vs 42% vs 36%, p=0.007). A low CFR (defined as CFR below the median of 2.4) in patients with SR showed significantly more revascularization compared with PAF and LSPAF (p&amp;lt;0.001), although more patients with LSPAF and low CFR underwent CAG (p&amp;lt;0.001). In patients with low CFR referred for CAG, the overall prevalence of obstructive coronary artery disease on CAG was 62%, with 30% for LSPAF, 52% for PAF and 78% for SR. There were no significant differences between SR, PAF and LSPAF in the occurrence of MI during a mean follow-up of 36 months (p=0.256). Conclusion A low CFR was only associated with a higher incidence of revascularization in patients with SR. Among patients with low CFR, LSPAF patients have the highest number of unnecessary CAGs as compared with SR and PAF. Funding Acknowledgement Type of funding sources: None.

Exercise capacity as a predictor of coronary microvascular dysfunction

Abstract Introduction Exercise capacity (EC) is an important prognostic test in patients with coronary artery disease (CAD). Positron-emission tomography (PET) is an important risk-stratifying tool to tailor management of patients with coronary artery disease. Purpose We aimed to assess EC in predicting positron emission tomography (PET) myocardial perfusion imaging (MPI) derived coronary flow reserve (CFR). Methods Consecutive patients who had clinically indicated PET MPI and EC were included. EC was defined based on peak metabolic equivalents (METS) achieved during exercise stress test. Myocardial blood flow (MBF) in ml/gm/min was obtained from dynamic PET MPI images at rest and peak hyperemia. The coronary flow reserve (CFR) was calculated as the ratio of stress to rest MBF of the left ventricle. Results The study population consisted of 511 patients who underwent PET MPI and EC testing (mean age 56 (±11), 71% male). Cardiovascular risk factors were prevalent (75% hypertensive, 82% dyslipidemic, 43% diabetics, 27% known CAD). Peak METS &amp;gt;6 was achieved in 81% of patients, and the CFR &amp;lt;2 was present in 27%. In multivariable logistic regression models adjusted for age, sex, cardiovascular risk factors (hypertension, diabetes, dyslipidemia) and medication use (angiotensin converting enzyme inhibitor/angiotensin receptor blocker, statins, beta-blockers), patients with peak METS &amp;gt;6 had a statistically significant lower odds of microvascular dysfunction (CFR &amp;lt;2: OR 0.43, 95% CI 0.26–0.71, p=0.001). Assessment of discrimination showed the model with CFR &amp;lt;2 had an incremental improvement of Harrell's C statistic over clinical variables (0.65 vs 0.69, p=0.02). Conclusion Our findings showed exercise capacity was a good predictor of CFR and microvascular coronary health over and above clinical variables. Further studies are needed to assess the prognostic interplay between EC and CFR. Funding Acknowledgement Type of funding sources: None.

Prognostic value of coronary flow reserve and coronary calcification in patients with suspected coronary artery disease

Abstract Introduction Current cardiac PET and computed tomography imaging allows the simultaneous acquisition of anatomic and physiological data for patients suspected of CAD. Purpose We aimed to evaluate the incremental prognostic value of coronary artery calcium (CAC) score and coronary flow reserve (CFR) in patients with suspected coronary artery disease (CAD) undergoing positron emission tomography (PET) myocardial perfusion imaging (MPI). Methods We included consecutive patients who underwent PET MPI and CAC score calculation at Houston Methodist Hospital between August 2019 and January 2022. MPI and CAC scores were obtained in the same setting. The primary endpoint of the study was MACE. Cox proportional hazard regression was used to assess the incremental prognostic value of CAC and CFR by sequentially adding the variables to a model that included clinical and PET variables. Results A total of 2,072 patients (mean age 65.7±11.6 years, 54.7% women) were included in the analysis. Risk factors were prevalent (86.1% hypertension, 75.2% dyslipidemia, 45.5% diabetes). In total, 25.3% of the cohort had a CAC score of 0, 38.1% had CAC ≥400, and 39.9% had CFR &amp;lt;2. Over a median follow up of 6.26 (IQR 1.7–12.4) months, 66 (3.2%) patients had cardiac death/nonfatal myocardial infarction. CFR score added incremental prognostic value over clinical and perfusion variables alone (base model: c-index 0.75; Akaike information criterion [AIC]: 1,860.6; p&amp;lt;0.001; CFR model: c-index 0.78; AIC: 1,842.4; p=0.041). However, CAC score did not show an increased prognostic utility (CAC model: c-index 0.76; AIC: 1,854.8; p=0.087 vs. base model), and neither did the combined model of CAC and CFR scores (c-index 0.79; AIC: 1,839.4; p=0.366 vs. CFR model). Conclusions Among patients referred for PET MPI, CFR score added an increased prognostic value over clinical and MPI variables. However, when evaluating the prognostic utility of CAC alone, or of CAC and CFR combined, the multivariable model did not show any increased prognostic potential. Funding Acknowledgement Type of funding sources: None.

The use of lipid-lowering medication after diagnostic imaging procedures in patients with chest pain

Abstract Background Coronary CT angiography (CTA) combined with myocardial perfusion imaging accurately detects both non-obstructive and obstructive coronary artery disease (CAD). Lipid-lowering therapy is known to effectively reduce cardiovascular events, but the impact of non-invasive imaging findings on the usage of lipid-lowering therapy remains largely unknown. Purpose To assess the use of lipid-lowering medication in patients referred to coronary CTA and subsequent positron emission tomography (PET) myocardial perfusion imaging due to suspected obstructive CAD. Methods We retrospectively analyzed data on purchases of lipid-lowering drugs obtained from the Finnish national registry for a time period starting 1 year before and ending 2 years after the date of diagnostic imaging. This time period was divided into six 6-month intervals, for each of which the presence of any statin and/or ezetimibe purchase was recorded. According to the local routine, patients with suspected obstructive (≥50%) stenosis on coronary CTA entered downstream 15O-water PET myocardial perfusion imaging during adenosine stress to assess the hemodynamic significance of the coronary stenosis. The use of medication was compared among patients with normal coronary arteries, non-obstructive CAD, and obstructive CAD. Results During 2008–2016, a total of 1973 patients (41% male, median age 63 years) underwent coronary CTA and 33% of these had PET perfusion imaging. There were 9081 purchases of lipid-lowering drugs during the 3-year observation period. There were 676 (34%) patients with normal coronary arteries, 640 (32%) patients with non-obstructive atherosclerosis on CTA, 325 (16%) patients with suspected obstructive stenosis on CTA but normal PET perfusion, and 332 (17%) patients with obstructive stenosis and abnormal hyperemic PET perfusion. The proportion of patients buying lipid-lowering drugs was 24%, 51%, 72%, and 91%, respectively, as assessed within the 6-month interval following the CTA/PET imaging. After diagnostic testing, proportion of patients purchasing lipid-lowering medications increased in all groups except those with normal coronary arteries (Figure 1). However, there was a marked decrease in all patient groups in proportion of patients using lipid-lowering medication towards the end of the 2-year follow-up period. Conclusions In a real-world cohort of symptomatic patients with chest pain undergoing diagnostic imaging for suspected CAD, subsequent purchases of lipid-lowering drugs increase in relation to the severity of imaging findings. Although majority of patients with obstructive CAD initially purchased lipid-lowering medication, our results indicate a marked decrease in the use of these preventive medications towards the end of 2-year follow-up period. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): State Research Funding of Turku University Hospital; the Academy of Finland; Finnish Foundation for Cardiovascular Research.

Importance of plaque volume and composition for the prediction of myocardial ischaemia using sequential coronary computed tomography angiography/positron emission tomography imaging.

Coronary atherosclerosis with a large necrotic core has been postulated to reduce the vasodilatory capacity of vascular tissue. In the present analysis, we explored whether total plaque volume and necrotic core volume on coronary computed tomography angiography (CCTA) are independently associated with myocardial ischaemia on positron emission tomography (PET). From a registry of symptomatic patients with suspected coronary artery disease and clinically indicated CCTA with sequential [15O]H2O PET myocardial perfusion imaging, we quantitatively measured diameter stenosis, total and compositional plaque volumes on CCTA. Primary endpoint was myocardial ischaemia on PET, defined as an absolute stress myocardial blood flow ≤2.4 mL/g/min in ≥1 segment. Multivariable prediction models for myocardial ischaemia were consecutively created using logistic regression analysis (stenosis model: diameter stenosis ≥50%; plaque volume model: +total plaque volume; plaque composition model: +necrotic core volume). A total of 493 patients (mean age 63 ± 8 years, 54% men) underwent sequential CCTA/PET imaging. In 153 (31%) patients, myocardial ischaemia was detected on PET. Diameter stenosis ≥50% (P < 0.001) and necrotic core volume (P = 0.029) were independently associated with myocardial ischaemia, while total plaque volume showed borderline significance (P = 0.052). The plaque composition model (χ2 = 169) provided incremental value for the prediction of ischaemia when compared with the stenosis model (χ2 = 138, P < 0.001) and plaque volume model (χ2 = 164, P = 0.021). The volume of necrotic core on CCTA independently and incrementally predicts myocardial ischaemia on PET, beyond diameter stenosis alone.

Incremental prognostic value of positron emission tomography derived left ventricular mass

BackgroundLeft ventricular hypertrophy has been shown to be an independent predictor of outcomes in patients with coronary artery disease (CAD). We aimed to determine the incremental prognostic value of positron emission tomography (PET) derived left ventricular mass (LVM) to clinical variables and myocardial flow reserve (MFR). MethodsWe included consecutive patients who had clinically indicated PET myocardial perfusion imaging for suspected or established CAD. Patients were followed from the date of PET imaging for major adverse cardiovascular events (MACE, inclusive of all-cause death, non-fatal myocardial infarction, and percutaneous coronary intervention/coronary artery bypass grafting 90 days after imaging). ResultsA total of 2357 patients underwent PET MPI during the study period (47% female, mean age 66 ± 12 years, 87% hypertensive, 47% diabetic, 79% dyslipidemia). After a mean follow-up of 11.6 ± 6.6 months, 141 patients (6.0%, 5.1 per 1000 person-year) experienced MACE (86 D/24 MI/39 PCI/9 CABG). In nested multivariable Cox models, LVM was not independently associated with outcomes (HR 1.00, P = .157) and had no incremental prognostic value (C index: 0.75, P = .571) over MFR and clinical variables. ConclusionOur analysis shows that LVM provides no independent and incremental prognostic value over MFR and clinical variables.

The Potential of F-18 Flurpiridaz PET/CT Myocardial Perfusion Imaging for Precision Imaging.

Myocardial perfusion imaging (MPI) with single photon emission computed tomography (SPECT) has been the main method for assessing patients with known or suspected coronary artery disease (CAD) for decades. Based on a strong and growing evidence base, positron emission tomography (PET) MPI is increasingly favored when it is available. However, currently available PET perfusion tracers have limitations that have hampered broad utilization. F-18 flurpiridaz is a novel PET MPI agent that is nearing completion of studies necessary to obtain regulatory approval. It has unique capabilities that will facilitate further expansion of PET MPI utilization. In addition, it has characteristics that may define it as the best MPI agent to date, in terms of the potential to equalize accuracy independent of patient size, gender, complexity, or ability to perform exercise stress. The combination of excellent image quality and accurate absolute blood flow quantification hold the potential of its being an ideal precision tool for non-invasive assessment of myocardial blood flow and entire spectrum of ischemic heart disease.