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.

Stabilization of Rapidly Progressive Cardiac Allograft Vasculopathy Using mTOR Inhibition After Heart Transplantation

BACKGROUND

Inhibition of the mammalian target of rapamycin (mTor) pathway after heart transplantation has been associated with reduced progression of coronary allograft vasculopathy (CAV). The application of low-dose mTOR inhibition in the setting of modern immunosuppression, including tacrolimus, remains an area of limited exploration.

METHODS

This retrospective study included patients who received heart transplantation between January 2009 and January 2019 and had baseline, 1-year and 2-3-year coronary angiography with intravascular ultrasound (IVUS). Intimal thickness in 5 segments along the left anterior descending artery was compared across imaging time points in patients who were transitioned to low-dose mTOR inhibitor (sirolimus) vs standard treatment with mycophenolate on a background of tacrolimus. Long-term adverse cardiovascular outcomes (revascularization, severe CAV, retransplant, and cardiovascular death) were also assessed.

RESULTS

Among 216 patients (mean age 51.5 ± 11.9 years, 77.8% men, 80.1% white), 81 individuals (37.5%) were switched to mTOR inhibition. mTOR inhibition was associated with a reduction in intimal thickness by 0.05 mm (95% CI 0.02-0.07; P < 0.001). This reduction was driven by patients who met the criteria for rapidly progressive CAV 1-year post-transplant (0.12 mm; P = 0.016 for interaction). After a median follow-up of 8.6 (IQR 6.6-11) years, 40 patients had major adverse cardiovascular outcomes. The use of mTOR inhibitors was not significantly associated with cardiovascular outcomes (P = 0.669).

CONCLUSION

Transitioning patients after heart transplantation to an immunosuppression regimen composed of low-dose mTOR inhibition and tacrolimus was associated with a lack of progression of CAV, particularly in those with rapidly progressive CAV at 1 year, but not with long-term cardiovascular outcomes.

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.

Pre- and Post-Implant Endoscopy in Left Ventricular Assist Device Recipients: A Single-Center Experience

Background

Gastrointestinal bleeding (GIB) is common in left ventricular assist devices (LVADs) patients, but the optimal screening approach before LVAD implantation is still unclear. The aim of the study was to describe our experience with pre- and post-LVAD implantation endoscopic screening and subsequent GI bleeding in this cohort.

Methods

A retrospective review was conducted among all patients who underwent LVAD implantation at Saint Luke's Hospital, between 2010 and 2020. The data were reviewed to determine the yield and safety of endoscopic procedures performed within 1 month before LVAD placement and the incidence of GIB within 1 year after implantation.

Results

A total of 167 LVAD patients met the inclusion criteria, and 23 underwent pre-implantation endoscopic evaluation. Angiodysplasia had a significantly higher odds ratio (OR) of 9.41 (95% confidence interval (CI): 2.01 - 44.09) in post-LVAD endoscopy, while there was no significant difference in bleeding from other sources such as peptic ulcer disease or diverticular bleeding. There was no difference in the incidence of GIB in patients who underwent endoscopic evaluation pre-LVAD compared to post-LVAD GIB (32.6% vs. 39.1%, P = 0.64). Endoscopy was well-tolerated in this cohort, and argon plasma coagulation was the most commonly used intervention to achieve hemostasis.

Conclusions

According to our results, we recommend against routine pre-LVAD endoscopic screening. Instead, we suggest an individualized approach, where decisions are made on a case-by-case basis.

Accurate and efficient rapid acquisition early post-injection stress-first CZT SPECT myocardial perfusion imaging with tetrofosmin and attenuation correction

INTRODUCTION

Myocardial perfusion imaging (MPI) protocols have not changed significantly despite advances in instrumentation and software. We compared an early post-injection, stress-first SPECT protocol to standard delayed imaging.

METHODS

95 patients referred for SPECT MPI were imaged upright and supine on a Spectrum Dynamics D-SPECT CZT system with CT attenuation correction. Patients received injection of 99mTc tetrofosmin at peak of regadenoson stress and were imaged. Early post-stress (mean 17 ± 2 minutes) and Standard 1-h delay (mean 61 ± 13 min). Three blinded readers evaluated images for overall interpretation, perceived need for rest imaging, image quality, and reader confidence. Laboratory efficiency was also evaluated.

RESULTS

Blinded readers had the same response for the need for rest in 77.9% of studies. Studies also had the same interpretation in 89.5% of studies. Reader confidence was high (86.0% (Early) and 90.3% (Standard p = 0.52. Image quality was good or excellent in 87.4% Early vs 96.8% Standard (p = 0.09). Time between patient check-in and end of stress imaging was 104 ± (Standard) to 60 ± 18 minutes (Early) (p < 0.001).

CONCLUSION

Early post-injection stress-only imaging using CZT SPECT/CT appears promising with Tc-99m tetrofosmin with similar image quality, reader confidence, diagnosis, and need for a rest scan.

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.

Hot spot imaging in cardiovascular diseases: an information statement from SNMMI, ASNC, and EANM

This information statement from the Society of Nuclear Medicine and Molecular Imaging, American Society of Nuclear Cardiology, and European Association of Nuclear Medicine describes the performance, interpretation, and reporting of hot spot imaging in nuclear cardiology. The field of nuclear cardiology has historically focused on cold spot imaging for the interpretation of myocardial ischemia and infarction. Hot spot imaging has been an important part of nuclear medicine, particularly for oncology or infection indications, and the use of hot spot imaging in nuclear cardiology continues to expand. This document focuses on image acquisition and processing, methods of quantification, indications, protocols, and reporting of hot spot imaging. Indications discussed include myocardial viability, myocardial inflammation, device or valve infection, large vessel vasculitis, valve calcification and vulnerable plaques, and cardiac amyloidosis. This document contextualizes the foundations of image quantification and highlights reporting in each indication for the cardiac nuclear imager.

Association of Tafamidis With Health Status in Patients With ATTR Cardiac Amyloidosis: A Post Hoc Analysis of the ATTR-ACT Randomized Clinical Trial

Importance

Tafamidis reduced all-cause mortality and cardiovascular-related hospitalizations and minimized patient-reported health status deterioration at 30 months in patients with transthyretin (ATTR) amyloidosis. However, the clinical significance of health status changes remains unclear, particularly in patients with New York Heart Association (NYHA) class III symptoms who experienced more cardiovascular-related hospitalizations than those with NYHA class I-II symptoms.

Objective

To evaluate the health status of patients taking tafamidis with baseline NYHA class III symptoms.

Design, Setting, and Participants

This randomized clinical trial post hoc analysis evaluated data for patients with transthyretin (ATTR) cardiac amyloidosis and NYHA class I-III symptoms at baseline who were enrolled in ATTR-ACT, a placebo-controlled study of tafamidis held at 48 sites in 13 countries.

Interventions

Tafamidis meglumine, 80 mg or 20 mg (pooled cohort), vs placebo.

Main Outcomes and Measures

Established thresholds for clinical benefit on the Kansas City Cardiomyopathy Questionnaire Overall Summary (KCCQ-OS) were used to define response groups (very large decline to very large improvement); the proportion of patients in each group was calculated within each baseline NYHA class.

Results

Among 441 patients (264 tafamidis, 177 placebo), the mean (SD) age was 74.3 (7.0) years; 398 (90%) were male and 43 (10%) were female. Mean (SD) baseline KCCQ-OS scores were 67.3 (21.4) in the tafamidis group and 65.9 (21.7) in the placebo group (range: 0-100, with 100 indicating the best health). There was a significant shift toward better KCCQ-OS scores in patients receiving tafamidis (odds ratio for 10-point improvement 2.4; 95% CI, 1.6-3.4; P < .001). More patients taking tafamidis were alive and not worse at all time points (37% vs 15% at month 30). These findings were similar in patients with NYHA class III symptoms. In patients with NYHA class III symptoms alive at 30 months, improvements in health status were more common (35% vs 10%) and declines were less common (38% vs 57%) with tafamidis vs placebo.

Conclusions and Relevance

In ATTR-ACT, although patients with baseline NYHA class III symptoms had worse overall outcomes, treatment with tafamidis yielded better health status compared with placebo.

Trial Registration

ClinicalTrials.gov Identifier: NCT01994889.

Primer on the Differential Diagnosis and Workup for Transthyretin Cardiac Amyloidosis

Amyloidosis has often been referred to as a "great masquerader," mimicking other systemic and cardiac diseases. As diagnostic techniques such as echocardiography with longitudinal strain, cardiac magnetic resonance imaging, and nuclear scintigraphy have advanced, identification of cardiac amyloidosis has become less daunting. This review covers the differential diagnosis and workup of patients with transthyretin cardiac amyloidosis, with a specific focus on developing a clinical suspicion through demographic, clinical, and echocardiographic features of the disease. The most common mimics of cardiac amyloidosis, i.e., conditions that likewise cause heart failure with preserved or mildly reduced ejection fraction, are also explored with respect to differential diagnosis, both for patients with normal and increased ventricular wall thickness. Ultimately, this review aims to demystify the diagnostic process by offering an algorithmic approach to the identification of transthyretin cardiac amyloidosis.

Recommendations for Multimodality Cardiovascular Imaging of Patients with Hypertrophic Cardiomyopathy: An Update from the American Society of Echocardiography, in Collaboration with the American Society of Nuclear Cardiology, the Society for Cardiovascular Magnetic Resonance, and the Society of Cardiovascular Computed Tomography

Hypertrophic cardiomyopathy (HCM) is defined by the presence of left ventricular hypertrophy in the absence of other potentially causative cardiac, systemic, syndromic, or metabolic diseases. Symptoms can be related to a range of pathophysiologic mechanisms including left ventricular outflow tract obstruction with or without significant mitral regurgitation, diastolic dysfunction with heart failure with preserved and heart failure with reduced ejection fraction, autonomic dysfunction, ischemia, and arrhythmias. Appropriate understanding and utilization of multimodality imaging is fundamental to accurate diagnosis as well as longitudinal care of patients with HCM. Resting and stress imaging provide comprehensive and complementary information to help clarify mechanism(s) responsible for symptoms such that appropriate and timely treatment strategies may be implemented. Advanced imaging is relied upon to guide certain treatment options including septal reduction therapy and mitral valve repair. Using both clinical and imaging parameters, enhanced algorithms for sudden cardiac death risk stratification facilitate selection of HCM patients most likely to benefit from implantable cardioverter-defibrillators.

The effect of recipient BMI on waitlist and post-transplant outcomes after the 2018 heart transplant allocation policy change

OBJECTIVE

The effects of recipient body mass index (BMI) on waitlist strategies, waitlist outcomes, and post-transplant outcomes among adult patients listed for heart transplantation under the updated 2018 allocation system have not been well characterized.

METHODS

The United Network of Organ Sharing data set between October 2015 and March 2021 was analyzed, and patients were grouped based on recipient BMI and whether listing occurred in the old (pre-October 2018) or new allocation system.

RESULTS

Listing strategies differed by BMI group, but trends of increased use of temporary mechanical support and decreased use of durable support remained among all BMI groups, except those with BMI > 35 kg/m² . Waitlist outcomes improved among all BMI cohorts in the new allocation system, including among patients with BMI 30-34.9 and >35 kg/m² , although patients with higher BMIs continued to have longer waitlist times. Post-transplant outcomes in the new allocation system are worse for patients with BMI > 30 kg/m²  (hazard ratio: 1.47; confidence interval: 1.19-1.82; p < .001).

CONCLUSIONS

The 2018 change to the heart transplant allocation system was associated with similar changes in the use of mechanical support for listing strategy across BMI ranges, except in the most obese, and improved waitlist outcomes across all BMI ranges. Post-transplant outcomes in the new allocation system are worse for patients with BMI > 30 kg/m²  compared to patients with BMI < 30 kg/m² . These findings have important clinical implications for our understanding of the ongoing influence of BMI on waitlist courses and post-transplant outcomes among patients listed for heart transplantation.

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.

Outpatient Management of Heart Failure During the COVID-19 Pandemic After Adoption of a Telehealth Model

OBJECTIVES

This study sought to determine whether the increased use of telehealth was associated with a difference in outcomes for outpatients with heart failure.

BACKGROUND

The COVID-19 pandemic led to dramatic changes in the delivery of outpatient care. It is unclear whether increased use of telehealth affected outcomes for outpatients with heart failure.

METHODS

In March 2020, a large Midwestern health care system, encompassing 16 cardiology clinics, 16 emergency departments, and 12 hospitals, initiated a telehealth-based model for outpatient care in the setting of the COVID-19 pandemic. A propensity-matched analysis was performed to compare outcomes between outpatients seen in-person in 2018 and 2019 and via telemedicine in 2020.

RESULTS

Among 8,263 unique patients with heart failure with 15,421 clinic visits seen from March 15 to June 15, telehealth was employed in 88.5% of 2020 visits but in none in 2018 or 2019. Despite the pandemic, more outpatients were seen in 2020 (n = 5,224) versus 2018 and 2019 (n = 5,099 per year). Using propensity matching, 4,541 telehealth visits in 2020 were compared with 4,541 in-person visits in 2018 and 2019, and groups were well matched. Mortality was similar for telehealth and in-person visits at both 30 days (0.8% vs 0.7%) and 90 days (2.9% vs 2.4%). Likewise, there was no excess in hospital encounters or need for intensive care with telehealth visits.

CONCLUSIONS

A telehealth model for outpatients with heart failure allowed for distanced encounters without increases in subsequent acute care or mortality. As the pressures of the COVID-19 pandemic abate, these data suggest that telehealth outpatient visits in patients with heart failure can be safely incorporated into clinical practice.

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.

Cardiac Amyloidosis Screening at Trigger Finger Release Surgery

Cardiac amyloidosis is often preceded by orthopedic manifestations such as carpal tunnel syndrome, and 10% of patients who underwent idiopathic carpal tunnel release surgery will have biopsy-confirmed amyloid deposits in the tenosynovial sheath. Trigger finger is also commonly reported in patients with amyloidosis and involves the same tendon sheath as carpal tunnel syndrome, but the prevalence of amyloid deposition is unclear. This prospective cross-sectional study enrolled 100 patients aged ≥50 years at the time of surgery for idiopathic trigger finger. Patients underwent release surgery, and a sample of the tenosynovium of the affected finger was excised, stained with Congo red, and subtyped with mass spectrometry if amyloid was demonstrated. Further cardiac evaluation was performed in patients with amyloid deposition. Of the 100 patients (mean age 65.5 ± 8.1 years) enrolled, only 2 demonstrated amyloid deposits on Congo red staining. One patient with previous proteinuric kidney disease had fibrinogen A α-chain amyloidosis, and the other patient had untyped amyloidosis. Neither patient had cardiac involvement. A total of 13 of the 100 patients underwent concomitant carpal tunnel release surgery, and 2 of these patients had amyloid deposits in the carpal tunnel with "false-negative" samples from the trigger finger tenosynovium. In conclusion, biopsy during trigger finger release surgery demonstrated a 2% yield for amyloidosis, which is significantly lower than the previously published yield of 10% during carpal tunnel release surgery. This observation has important implications for the development of diagnostic algorithms to screen patients for amyloidosis during orthopedic operations.

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.

Spironolactone in Patients With an Echocardiographic HFpEF Phenotype Suggestive of Cardiac Amyloidosis: Results From TOPCAT

OBJECTIVES

This study investigated an enriched cohort of patients with heart failure and preserved ejection fraction (HFpEF) in TOPCAT (Treatment of Preserved Cardiac Function Heart Failure With an Aldosterone Antagonist) with an echocardiographic phenotype of cardiac amyloidosis.

BACKGROUND

There is a high prevalence of increased interventricular septal (IVS) thickness and decreased mitral annular systolic (s') velocity in cardiac amyloidosis. In addition, clinical trials of neurohormonal blockade are missing in this population.

METHODS

TOPCAT randomized patients with HFpEF to spironolactone or placebo therapy with a primary endpoint of cardiovascular death, HF hospitalization, or aborted cardiac arrest. Patients with IVS and s' velocity measurements were included, and adjusted Cox models assessed the effect of echocardiographic variables and spironolactone on the primary endpoint.

RESULTS

Among 590 patients, mean s' velocity was 6.4 ± 2.1 cm/s and IVS thickness was 1.2 ± 0.2 cm. The enriched cohort with characteristics of cardiac amyloidosis (s' velocity ≤6 cm/s and IVS thickness ≥1.2 cm) included 135 patients (23% of the cohort). After a median follow-up of 2.6 years (1.5-3.9 years), these patients had the worst prognosis (adjusted HR: 2.10; 95% CI: 1.26-3.50; P = 0.004). Both s' velocity and IVS thickness were individually associated with the primary endpoint, and abnormalities in these parameters were additive as lower s' velocity was particularly prognostic in those with greater IVS thickness (interaction: P = 0.013). Spironolactone was associated with improved outcomes in the overall cohort (P = 0.024), and patients in the enriched cohort had a benefit similar to that in other groups (interaction: P = 0.382).

CONCLUSIONS

An enriched subset of patients with structural and functional echocardiographic features of cardiac amyloidosis had the worst prognosis in the TOPCAT study, but they benefitted similarly from spironolactone therapy. Future studies of mineralocorticoid receptor antagonists in patients with cardiac amyloidosis are warranted.

Development and Piloting of a Patient-Centered Report Design for Stress Myocardial Perfusion Imaging Results

IMPORTANCE

The management of coronary disease epitomizes the call to better engage patients in shared medical decision-making. Myocardial perfusion imaging (MPI) is the foundation of diagnosis, risk stratification, and subsequent therapy; however, MPI reports are currently interpretable by specialists but not patients.

OBJECTIVE

To design and test a patient-centered report for stress MPI test results.

DESIGN, SETTING, AND PARTICIPANTS

This qualitative study of outpatients who underwent an MPI stress test and clinicians used a mixed methods approach. Phase 1 (December 2018 to July 2019) used qualitative methods to design a patient-centered reporting tool, with 5 focus groups with 36 patients and 2 focus groups with 27 clinicians. Phase 2 (June to September 2019) consisted of pilot testing the reporting tool with feedback from a structured survey given to patients who received MPI reports before and after implementing the tool.

MAIN OUTCOMES AND MEASURES

Key themes around patient experiences with the current MPI reporting and their desire for a more useful report were identified, which led to a sample reporting tool after serial iterations with feedback. Differences in patient knowledge and engagement were assessed between patients before and after implementation of the new reporting tool using χ2 tests.

RESULTS

From patient focus groups (26 patients; mean [SD] age, 66.3 [9.6] years, 9 [35%] women), 3 themes on the inadequacies of current MPI reporting were identified: (1) inconsistent delivery of results, (2) use of medical jargon, and (3) unclear posttest course. We identified 5 themes for a more patient-centered MPI report: desire for written information, discussion of the report with medical personnel, presentation of results in simple language with use of visual graphics, comparisons with normal results, and personalized risk estimates. In a pilot survey with 123 patients split into a pre-implementation group (69 patients; mean [SD] age, 68.2 [8.5] years; 27 [51%] women) and a postimplementation group (54 patients; mean [SD] age, 66.4 [8.7] years; 30 [56%] women), the patient-centered report led to more patients reading the entire report (45 [83%] vs 46 [67%]; P = .04) and improved knowledge of future risk of cardiac events (41 [76%] vs 20 [29%]; P < .001). There was also a numerically higher percentage of patients who found the report easy to read (45 [83%] vs 44 [68%]; P = .05) and understand (42 [78%] vs 43 [66%]; P = .16), although these results were not statistically significant.

CONCLUSIONS AND RELEVANCE

This study identified key elements of a patient-centered report design for stress MPI test results, which improved patient engagement and knowledge. These preliminary data support further implementation and study of a more patient-centered MPI report.

Current Updates on the Management of AL Amyloidosis

Systemic immunoglobulin light chain (AL) amyloidosis is a rare but fatal disease. It results from clonal proliferation of plasma cells with excessive production of insoluble misfolded proteins that aggregate in the extracellular matrix, causing damage to the normal architecture and function of various organs. For decades, treatment for AL amyloidosis was based mainly on therapeutic agents previously studied for its more common counterpart, multiple myeloma. As the prevalence and incidence of AL amyloidosis have increased, ongoing research has been conducted with treatments typically used in myeloma with varying success. In this review, we focus on current treatment strategies and updates to clinical guidelines and therapeutics for AL amyloidosis.

Relationship between coronary artery calcium score and myocardial blood flow reserve in patients with suspected coronary artery disease

Funding Acknowledgements

Type of funding sources: None.

Background

Both the Coronary Artery Calcium Score (CACS), a non-invasive surrogate for atherosclerotic burden, and reduced myocardial blood flow reserve (MBFR) with normal perfusion, a non-invasive surrogate for coronary vasomotor dysfunction, independently predict future cardiovascular events. The relationship between CACS and MBFR, and potential clinical factors affecting it, is not well understood.

Methods

Among 9467 consecutive patients without known history of CAD who had normal perfusion on 82Rb PET-CT and a concomitantly measured CACS between 01/2010 - 06/2020 within our health system, we assessed the relationship between CACS and MBFR. Multiple linear regression was used to predict MBFR using CACS, adjusted for age, sex, BMI, risk factors, symptoms, resting LVEF and vital signs. Interactions of age, sex, diabetes, and symptoms with CACS were assessed to evaluate if they modified the relationship of CACS with MBFR.

Results

Mean age (SD) of the study cohort was 66.4 (12.6) years, 64% were women, 64% had chest pain and 47% had dyspnea. Reduced MBFR (&lt;2) was present in 44% and CAC &gt;0 in 74% of patients.  There was a modest inverse correlation between MBFR and CACS, r= - 0.18, p = &lt; 0.0001 (Figure). In adjusted analyses, CACS (β for CAC per 100 = -0.013 [95% CI: -0.015, -0.010]) was weakly associated with MBFR, and age, sex, diabetes, or symptoms did not modify this relationship (all interaction p-values &gt;0.1). Older age, female sex, presence of hypertension, diabetes, dyspnea, lower LVEF, higher baseline HR and higher CACS independently predicted reduced MBFR, but explained only 20% of the variance in MBFR (R2 =0.20).

Conclusion

There is a weak relationship between CACS and MBFR, which is not modified by age, sex, symptoms, or other CV risk factors. Coronary calcium burden does not completely reflect the overall disease activity within the coronary circulation, and measures of coronary vasomotor function such as MBFR may offer complementary information on CAD risk to that provided by the total burden of calcified atherosclerosis.

Pilot Study of F18-Florbetapir in the Early Evaluation of Cardiac Amyloidosis

Background: Cardiac amyloidosis is an increasingly recognized etiology of heart failure, in part due to the rise of non-invasive nuclear bone scintigraphy. Molecular imaging using positron emission tomography (PET) has promised the direct visualization of cardiac amyloid fibrils. We sought to assess the performance of F18-florbetapir PET in patients with a potential for cardiac amyloidosis in order to identify early disease.

Methods: We performed a pilot study of 12 patients: one with asymptomatic transthyretin cardiac amyloidosis, seven with a potential for developing cardiac amyloidosis (two smoldering myeloma and five with extracardiac biopsy demonstrating transthyretin amyloid deposits and negative technetium pyrophosphate scans), and four controls. Patients were imaged with PET/CT in listmode 10–20 min after receiving F18-florbetapir. Static images were created from this acquisition, and mean standardized uptake values (SUVs) of the left ventricular myocardium, blood pool, paraspinal muscles, and liver were calculated.

Results: All 12 patients demonstrated radiotracer uptake in the myocardium with mean SUV of 2.3 ± 0.4 and blood pool SUV of 0.8 ± 0.1. The patient with cardiac amyloidosis had SUV of 3.3, while mean SUV for patients at risk was 2.3 ± 0.4 and for controls was 2.2 ± 0.3. After 3 years of follow-up, one patient with SUV below the mean was subsequently diagnosed with ATTR cardiac amyloidosis.

Conclusion: In this cohort, PET with F18-florbetapir demonstrated non-specific radiotracer uptake in the myocardium in all patients using a static image protocol; though, the highest values were noted in a patient with ATTR cardiac amyloidosis. There was no difference in the intensity of F18-florbetapir uptake in at-risk patients and controls. Future studies should continue to investigate metabolic PET tracers and protocols in cardiac amyloidosis, including in early disease.

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.

Comparison of Outcomes Among Patients With Cardiogenic Shock Admitted on Weekends Versus Weekdays

Cardiogenic shock (CS) is associated with high mortality and often requires involvement of a multidisciplinary provider team to deliver timely care. Care coordination is more difficult on weekends, which may lead to a delay in care. We sought to assess the effect of weekend admissions on outcomes in patients admitted with CS. Patients admitted with CS were identified from 2005 to 2014 in the National Inpatient Sample using ICD9 code 785.51. Baseline demographics, in-hospital procedures, and outcomes were obtained and compared by day of admission. A multivariable model was used to assess the impact of weekend admission on in-hospital mortality. A total of 875,054 CS admissions were identified (age 67.4 ± 15.1 years, 40.2% female, 72.1% Caucasian), with 23% of patients being admitted on weekends. Baseline co-morbidities were similar between groups. Weekend admissions were associated with higher in-hospital mortality (40.6% vs 37.5%) and cardiac arrest (20.3% vs 18.1%, p < 0.001 for both) consistently over the study period. Use of temporary and permanent mechanical support devices and heart transplantation were slightly less common for weekend admissions. In a multivariable model adjusting for relevant confounders, weekend admission was associated with a 10% increased mortality in patients with CS. In conclusion, patients with CS admitted on weekends had higher in-hospital mortality and were slightly less likely to receive mechanical support and advanced therapies compared with those admitted on weekdays. Future studies and health system initiatives should focus on rectifying these disparities with around-the-clock multidisciplinary coordinated care for CS.

Effects of GLP-1 receptor agonists and SGLT-2 inhibitors in heart transplant patients with type 2 diabetes: Initial report from a cardiometabolic center of excellence

Type 2 diabetes mellitus (T2D) is a common comorbidity among patients who have undergone heart transplantation. Recently two classes of glucose-lowering medications (sodium-glucose cotransporter type-2 inhibitors [SGLT-2Is] and glucagon-like-peptide-1 receptor agonists [GLP-1RAs]), have been shown to significantly improve cardiovascular outcomes. There is a paucity of data regarding their use in immunosuppressed patients, with many studies specifically excluding this population. We retrospectively evaluated the safety and efficacy of GLP-1RAs and SGLT-2Is in patients who had undergone orthotopic heart transplant at a high-volume center. Among 21 patients, we found significant weight loss, reductions in insulin use, hemoglobin A1c, and low-density lipoprotein-cholesterol. Moreover, both SGLT-2Is and GLP-1RAs were well tolerated with no adverse events leading to discontinuation of either therapy. While larger studies of patients after solid organ transplant are needed, this small hypothesis-generating study demonstrates that SGLT-2Is and GLP-1RAs appear safe and effective therapies among patients with T2D after heart transplant.

PCSK9 Inhibitors in Heart Transplant Patients: Safety, Efficacy, and Angiographic Correlates

BACKGROUND

Statins are recommended in heart transplant patients, but are sometimes poorly tolerated. Alternative agents are often considered including proprotein convertase subtilisin/kexin type-9 inhibitors (PCSK9i). We sought to investigate the use of PCSK9i after heart transplantation.

METHODS AND RESULTS

We identified patients who received a heart transplant from 1999 to 2019 and were started on PCSK9i at our institution. Clinical, laboratory, and coronary angiography with intravascular ultrasound results were compared. Among 65 patients initiated on PCSK9i (48 for statin intolerance and 17 for refractory hyperlipidemia), the median time from transplant was 5.5 years (interquartile range [IQR], 2.8-9.9 years) with a median PCSK9 treatment duration of 1.6 years (IQR, 0.8-3.2 years) and 80% still on treatment. Evolocumab was used in 73.8%, alirocumab in 12.3%, and both in 13.8% owing to insurance coverage. All patients required prior authorization; initial denial occurred in 18.5% and 32.3% had denials in subsequent years. The median low-density lipoprotein cholesterol decreased from 130 mg/dL (IQR, 102-148 mg/dL) to 55 mg/dL (IQR, 35-74 mg/dL) after starting PCSK9i (P < .001), with 72% of patients achieving a low-density lipoprotein cholesterol of <70 mg/dL after treatment. There were also significant reductions of total cholesterol, non-high-density lipoprotein cholesterol, total/high-density lipoprotein cholesterol ratio, and triglycerides, with a modest increase in high-density lipoprotein cholesterol. These changes were durable at latest follow-up. In 33 patients with serial coronary angiography and intravascular ultrasound, PCSK9i were associated with stable coronary plaque thickness and lumen area.

CONCLUSIONS

Among heart transplant recipients, PCSK9i are effective in lowering cholesterol levels and stabilizing coronary intimal hyperplasia with minimal side effects. Despite favorable effects, access and affordability remain a challenge.

Single-center utilization of donor-derived cell-free DNA testing in the management of heart transplant patients

BACKGROUND

Gene expression profiling (GEP) and donor-derived cell-free DNA (dd-cfDNA) are useful in acute rejection (AR) surveillance in orthotopic heart transplant (OHT) patients. We report a single-center experience of combined GEP and dd-cfDNA testing for AR surveillance.

METHODS

GEP and dd-cfDNA are tested together starting at 2 months post-OHT. After 6 months, combined testing was obtained before scheduled endomyocardial biopsy (EMB), and EMB was canceled with a negative dd-cfDNA. This approach was compared to using a GEP-only approach, where EMB was canceled with a negative GEP. We evaluated for frequency of EMB cancellation with dd-cfDNA usage.

RESULTS

A total of 153 OHT patients over a 13-month period underwent 495 combined GEP/dd-cfDNA tests. 82.2% of dd-cfDNA tests were below threshold. Above threshold results identified high-risk patients who developed AR. 378 combined tests ≥6 months post-OHT resulted in cancellation of 83.9% EMBs as opposed to 71.2% with GEP surveillance alone. There were 2 acute cellular and 2 antibody-mediated rejection episodes, and no significant AR ≥6 months.

CONCLUSION

Routine dd-cfDNA testing alongside GEP testing yielded a significant reduction in EMB volume by re-classifying GEP (+) patients into a lower risk group, without reduction in AR detection. The addition of dd-cfDNA identified patients at higher risk for AR.

Influence of Donor Transmitted and Rapidly Progressive Coronary Vascular Disease on Long-Term Outcomes After Heart Transplantation: A Contemporary Intravascular Ultrasound Analysis

BACKGROUND

Donor-transmitted atherosclerosis (DTA) and rapidly progressive cardiac allograft vasculopathy (CAV) at 1 year are intravascular ultrasound (IVUS)-derived measures shown to predict adverse cardiovascular outcomes in the setting of early generation immunosuppressive agents. Given the paucity of data on the prognostic value of IVUS-derived measurements in the current era, we sought to explore their association with adverse outcomes after heart transplantation.

METHODS AND RESULTS

This is a retrospective cohort analysis of patients who underwent heart transplantation at our center between January 2009 and June 2016 with baseline and 1-year IVUS. Five IVUS sections were prospectively analyzed for intimal thickness and lumen area. DTA was defined as maximum intimal thickness of 0.5 mm or greater at baseline, and rapidly progressive CAV as an increase in maximum intimal thickness by 0.5 mm or more at 1 year. Our primary analysis assessed the relationship of IVUS and other clinical data on a composite outcome: coronary intervention, CAV stage 2 or 3 (defined by the International Society for Heart and Lung Transplantation 2010 nomenclature), or cardiovascular death. Among 249 patients (mean age 51.0 ± 12.2 years and 74.3% male) included in the analysis, DTA was detected in 118 patients (51.4%). Over a median follow-up of 6.1 years (interquartile range 4.2-8.0 years), 45 patients met the primary end point (23 percutaneous coronary intervention, 11 CAV 2 or 3, and 11 cardiovascular deaths as first event). DTA and rapidly progressive CAV were not associated with the primary end point, all-cause mortality, or retransplantation. In an additional analysis including post-transplant events, incident rejection was strongly associated with poor outcomes, although cytomegalovirus infection was not.

CONCLUSIONS

In this contemporary cohort, IVUS-derived DTA and rapidly progressive CAV were not associated with medium- to long-term adverse events after heart transplantation.

Digoxin Use in Cardiac Amyloidosis

Despite limited options for rate control of atrial fibrillation and for low-output heart failure seen in cardiac amyloidosis (CA), digoxin use is discouraged due to a reported increased risk of sensitivity and toxicity. We present our experience with digoxin use in patients with CA and report the event rate of suspected digoxin-related arrhythmias and toxicity. This is a retrospective study of patients with CA seen at our institution between November 1995 and October 2018. Patients were screened for a history of ≥7 days of continuous digoxin use and stratified based on amyloid precursor protein-transthyretin (ATTR) and immunoglobulin light chain (AL). Medical records were used to identify suspected digoxin-related arrhythmias and toxicity events. Digoxin was used in 69 patients (42 ATTR, 27 AL) for a median duration of 6 months (IQR, 1 to 16). Indication for use was rate control in 64% of patients and symptomatic heart failure management in 36%. Suspected digoxin-related arrhythmias and toxicity events occurred in 12% of patients. No deaths were attributed to digoxin use or toxicity, but 11 patients died while on digoxin-most due to progressive heart failure in the setting of CA. In conclusion, digoxin may be a therapeutic option for rate and symptom control for some patients with AL-CA and ATTR-CA. Rigorous patient selection is recommended, and patients should be closely monitored during digoxin administration.

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.

Cost-Effectiveness of Tafamidis Therapy for Transthyretin Amyloid Cardiomyopathy

BACKGROUND

In patients with transthyretin amyloid cardiomyopathy, tafamidis reduces all-cause mortality and cardiovascular hospitalizations and slows decline in quality of life compared with placebo. In May 2019, tafamidis received expedited approval from the US Food and Drug Administration as a breakthrough drug for a rare disease. However, at $225 000 per year, it is the most expensive cardiovascular drug ever launched in the United States, and its long-term cost-effectiveness and budget impact are uncertain. We therefore aimed to estimate the cost-effectiveness of tafamidis and its potential effect on US health care spending.

METHODS

We developed a Markov model of patients with wild-type or variant transthyretin amyloid cardiomyopathy and heart failure (mean age, 74.5 years) using inputs from the ATTR-ACT trial (Transthyretin Amyloidosis Cardiomyopathy Clinical Trial), published literature, US Food and Drug Administration review documents, healthcare claims, and national survey data. We compared no disease-specific treatment ("usual care") with tafamidis therapy. The model reproduced 30-month survival, quality of life, and cardiovascular hospitalization rates observed in ATTR-ACT; future projections used a parametric survival model in the control arm, with constant hazards reduction in the tafamidis arm. We discounted future costs and quality-adjusted life-years by 3% annually and examined key parameter uncertainty using deterministic and probabilistic sensitivity analyses. The main outcomes were lifetime incremental cost-effectiveness ratio and annual budget impact, assessed from the US healthcare sector perspective. This study was independent of the ATTR-ACT trial sponsor.

RESULTS

Compared with usual care, tafamidis was projected to add 1.29 (95% uncertainty interval, 0.47-1.75) quality-adjusted life-years at an incremental cost of $1 135 000 (872 000-1 377 000), resulting in an incremental cost-effectiveness ratio of $880 000 (697 000-1 564 000) per quality-adjusted life-year gained. Assuming a threshold of $100 000 per quality-adjusted life-year gained and current drug price, tafamidis was cost-effective in 0% of 10 000 probabilistic simulations. A 92.6% price reduction from $225 000 to $16 563 would be necessary to make tafamidis cost-effective at $100 000/quality-adjusted life-year. Results were sensitive to assumptions related to long-term effectiveness of tafamidis. Treating all eligible patients with transthyretin amyloid cardiomyopathy in the United States with tafamidis (n=120 000) was estimated to increase annual healthcare spending by $32.3 billion.

CONCLUSIONS

Treatment with tafamidis is projected to produce substantial clinical benefit but would greatly exceed conventional cost-effectiveness thresholds at the current US list price. On the basis of recent US experience with high-cost cardiovascular medications, access to and uptake of this effective therapy may be limited unless there is a large reduction in drug costs.

Non-cardiac uptake of technetium-99m pyrophosphate in transthyretin cardiac amyloidosis

BACKGROUND

Technetium-based bone scintigraphy is rapidly becoming the most common non-invasive imaging tool in the diagnosis of Transthyretin cardiac amyloidosis (ATTR). Skeletal muscle uptake has been described with technetium-99m-3,3-diphosphono-1,2-propanodicarboxylic acid (TcDPD), and may account for masking of bony uptake. We sought to investigate skeletal muscle uptake of technetium-99m-pyrophosphate (TcPYP) in patients with ATTR.

METHODS AND RESULTS

This was a retrospective analysis of 57 patients diagnosed with ATTR who underwent TcPYP scintigraphy. Cardiac uptake was assessed on whole-body planar imaging using a semiquantitative scale (grades 0 to 3) and on single-photon emission computed tomography (SPECT) with CT attenuation correction using total myocardial counts per voxel after a 3-hour incubation. Skeletal muscle (psoas and biceps), vertebral body, LV myocardium, and blood pool mean counts were calculated. In the cohort (age 78 ± 9 years, 77% male, and 30% hereditary ATTR), there was no visualized tracer uptake in skeletal muscle or soft tissue on qualitative SPECT assessment. Total and blood pool-corrected uptake in the muscle groups were significantly less than myocardium and bone (P < 0.001). Blood pool-corrected muscle uptake was not associated with semiquantitative grade 3 vs 2 uptake (psoas P = 0.66, biceps P = 0.13) or presence of hereditary ATTR (psoas P = 0.43, biceps P = 0.69). As bony uptake decreased, there was no corresponding increase in skeletal muscle uptake.

CONCLUSIONS

In patients with ATTR cardiac amyloidosis, skeletal muscle uptake of TcPYP is minimal when assessed by qualitative and quantitative metrics, and is not significantly different in patients with grade 2 vs 3 semiquantitative uptake. The properties of this tracer may be different than TcDPD with respect to non-cardiac uptake.

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.