The Evolving Landscape of Impella Use in the United States Among Patients Undergoing Percutaneous Coronary Intervention With Mechanical Circulatory Support.

BACKGROUND: Impella was approved for mechanical circulatory support (MCS) in 2008, but large-scale, real-world data on its use are lacking. Our objective was to describe trends and variations in Impella use, clinical outcomes, and costs across US hospitals in patients undergoing percutaneous coronary intervention (PCI) treated with MCS (Impella or intra-aortic balloon pump). METHODS: From the Premier Healthcare Database, we analyzed 48 306 patients undergoing PCI with MCS at 432 hospitals between January 2004 and December 2016. Association analyses were performed at 3 levels: time period, hospital, and patient. Hierarchical models with propensity adjustment were used for association analyses. We examined trends and variations in the proportion of Impella use, and associated clinical outcomes (in-hospital mortality, bleeding requiring transfusion, acute kidney injury, stroke, length of stay, and hospital costs). RESULTS: Among patients undergoing PCI treated with MCS, 4782 (9.9%) received Impella; its use increased over time, reaching 31.9% of MCS in 2016. There was wide variation in Impella use across hospitals (>5-fold variation). Specifically, among patients receiving Impella, there was a wide variation in outcomes of bleeding (>2.5-fold variation), and death, acute kidney injury, and stroke (all ≈1.5-fold variation). Adverse outcomes and costs were higher in the Impella era (years 2008-2016) versus the pre-Impella era (years 2004-2007). Hospitals with higher Impella use had higher rates of adverse outcomes and costs. After adjustment for the propensity score, and accounting for clustering of patients by hospitals, Impella use was associated with death: odds ratio, 1.24 (95% CI, 1.13-1.36); bleeding: odds ratio, 1.10 (95% CI, 1.00-1.21); and stroke: odds ratio, 1.34 (95% CI, 1.18-1.53), although a similar, nonsignificant result was observed for acute kidney injury: odds ratio, 1.08 (95% CI, 1.00-1.17). CONCLUSIONS: Impella use is rapidly increasing among patients undergoing PCI treated with MCS, with marked variability in its use and associated outcomes. Although unmeasured confounding cannot be ruled out, when analyzed by time periods, or at the hospital level or the patient level, Impella use was associated with higher rates of adverse events and costs. More data are needed to define the appropriate role of MCS in patients undergoing PCI.

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.

Drivers of radiation dose reduction with myocardial perfusion imaging: A large health system experience.

BACKGROUND: Despite increasing emphasis on reducing radiation exposure from myocardial perfusion imaging (MPI), the use of radiation-sparing practices (RSP) at nuclear laboratories remains limited. Defining real-world impact of RSPs on effective radiation dose (E) can potentially further motivate their adoption. METHODS: MPI studies performed between 1/2010 and 12/2016 within a single health system were included. Mean E was compared between sites with 'basic' RSP (defined as elimination of thallium-based protocols and use of stress-only (SO) imaging on conventional single photon emission computed tomography (SPECT) cameras) and those with 'advanced' capabilities (sites that additionally used solid-state detector (SSD) SPECT cameras, advanced post-processing software (APPS) or positron emission tomography (PET) imaging), after matching patients by age, gender, and weight. Contributions of individual RSP to E reduction were determined using multiple linear regression after adjusting for factors affecting tracer dose. RESULTS: Among 55,930 MPI studies performed, the use of advanced RSP was associated with significantly lower mean E compared to basic RSP (7 ± 5.6 mSv and 16 ± 5.4 mSv, respectively; P < 0.001), with a greater likelihood of achieving E < 9 mSv (65.7% vs. 10.8%, respectively; OR 15.8 [95% CI 14 to 17.8]; P < 0.0001). Main driver of E reduction was SO-SSD SPECT (mean reduction = 11.5 mSv), followed by use of SO-SPECT + APPS (mean reduction = 10.1 mSv), ;ET (mean reduction = 9.7 mSv); and elimination of thallium protocols (mean reduction = 9.1 mSv); P < 0.0001 for all comparisons. CONCLUSION: In a natural experiment with implementation of radiation-saving practices at a large health system, stress-only protocols used in conjunction with modern SPECT technologies, the use of PET and elimination of thallium-based protocols were associated with greatest reductions in radiation dose. Availability of several approaches to dose reduction within a health system can facilitate achievement of targeted radiation benchmarks in a greater number of performed studies.

Diagnosis and Prognosis of Coronary Artery Disease with SPECT and PET.

PURPOSE OF REVIEW: Radionuclide myocardial perfusion imaging (MPI) continues to be the most reliable modality for diagnosis of hemodynamically significant coronary artery disease (CAD). The application of radionuclide MPI using single photon emission computed tomography (SEPCT) and positron emission tomography (PET) for CAD is reviewed, with emphasis on diagnosis and risk stratification. RECENT FINDINGS: Contemporary studies have reported the diagnostic and prognostic value of novel imaging protocols, employing stress-first or stress-only approach. In addition, the superior diagnostic value of PET has been established with a role of assessment of myocardial blood flow to improve risk stratification. The utility of MPI in special populations, such as the elderly, women, and diabetic patients has also been recently evaluated. Furthermore, multicenter studies have reported a similar diagnostic and prognostic value of radionuclide MPI compared with other functional and anatomical techniques for CAD. Radionuclide MPI with SPECT and PET are efficacious for diagnosis and prognosis of CAD. Its universal application in varied patient populations highlights its excellent clinical effectiveness.

Assessment of myocardial blood flow and coronary flow reserve with positron emission tomography in ischemic heart disease: current state and future directions.

Positron emission tomography (PET) is a versatile imaging technology that allows assessment of myocardial perfusion, both at a spatially relative scale and also in absolute terms, thereby enabling noninvasive evaluation of myocardial blood flow (MBF) and coronary flow reserve (CFR). Assessment of MBF using FDA-approved PET isotopes, such as 82Rb and 13N-ammonia, has been well validated, and several software packages are currently available, thereby allowing for MBF evaluation to be incorporated into routine workflow in contemporary nuclear laboratories. Incremental diagnostic and prognostic information provided with the knowledge of MBF has the potential for widespread applications. Improving the ability to identify the true burden of obstructive epicardial coronary stenoses and allowing for noninvasive assessment of coronary micro circulatory function can be achieved with MBF assessment. On the other hand, attenuated CFR has been shown to predict adverse cardiovascular prognosis in a variety of clinical settings and patient subgroups. With expanding applications of MBF, this tool promises to provide unique insight into the integrity of the entire coronary vascular bed beyond what is currently available with relative perfusion assessment. This review intends to provide an in-depth discussion of technical and clinical aspects of MBF assessment with PET as it relates to patients with ischemic heart disease.

The utility of ADMIRE-HF risk score in predicting serious arrhythmic events in heart failure patients: incremental prognostic benefit of cardiac 123I-mIBG scintigraphy.

BACKGROUND: A minority of heart failure (HF) patients who undergo implantable cardioverter defibrillator (ICD) implantation for primary prevention of sudden cardiac death (SCD) receive device therapy. Whether the addition of mIBG scintigraphy to conventional markers of arrhythmic risk can provide incremental risk stratification in HF patients has not been investigated. METHODS: We identified 778 patients from the ADMIRE-HF study with LVEF < 35% and class II or III HF symptoms who did not have an ICD at the time of enrollment. Patients were followed up prospectively (median 5 17 months) for occurrence of arrhythmic events (ArE). Heart-to-mediastinum ratio (HMR) was determined as a measure of relative myocardial sympathetic nerve activity at baseline using 123I-mIBG. The primary endpoint was the first occurrence of ArE: a composite of SCD, appropriate ICD therapy, resuscitated cardiac arrest or sustained ventricular tachycardia. Multivariate regression was used to determine independent predictors of ArE and to derive a risk score for ArE prediction. The score was used to group patients according to their risk for ArE. Integrated discrimination improvement (IDI) was used to quantify improvement in risk assessment with addition of HMR. RESULTS: ArE occurred in 54 patients (6.9%). ArE predictors were:HMR < 1.6 (HR 3.5, 95%CI [1.52-8], P 5 .02), LVEF < 25% (HR 2.0, 95% CI [1.28-3.05], P 5 .04) and SBP < 120 (HR 1.2,95%CI [1.03-1.39], P 5 .02). Event rates in the low-, intermediate-, and high risk groups were 2, 10 and 16%, respectively (P 5 .001). The score significantly improved risk prediction(IDI 5 45%, P 0.03). CONCLUSION: 123I-mIBG significantly provides incremental risk stratification for ArE in HF patients.

Appraisal of amyloidosis imaging practices in the Middle East/North Africa (PYP-MENA).

Aims: Whereas recommendations to optimize performance and yield of cardiac scintigraphy studies with bone-seeking tracers have been published, little is known about real-world adherence to these best practices, especially outside North America and Europe. Accordingly, we described imaging practices with this modality in a sample of nuclear laboratories in the Middle East/North Africa (MENA) region. Methods and results: Laboratories performing radionuclide imaging for cardiac amyloidosis in the MENA region were invited to participate in this study to describe installed camera systems, type and dose of bone-avid tracers used, imaging protocols, and criteria used for study interpretation. Out of 19 invited sites, 10 completed the survey (70% government-run; 90% accredited), sites have been involved with amyloid imaging for a median of 49 months (interquartile range 24-60). The median injected dose was 20 mCi (range 10-25), and PYP was used by 90% of sites in this sample. Planar imaging with single photon emission computed tomography (SPECT) reconstruction was performed at all sites, including seven sites that performed SPECT/CT reconstruction. Lastly, only 50% of sites relied on evidence of myocardial uptake by SPECT to confirm the diagnosis of ATTR cardiomyopathy, while the rest relied on visual assessment and heart/contralateral ratio. Conclusion: This study is the first to describe variation in imaging practices across sites in the MENA region, especially in acquisition protocols and interpretation standards. Eliminating heterogeneities identified by this study will harmonize image interpretation and reporting and will facilitate successful conduct of regional multi-centre studies.

Initiation of statin therapy after acute myocardial infarction is not associated with worsening depressive symptoms: insights from the Prospective Registry Evaluating Outcomes After Myocardial Infarctions: Events and Recovery (PREMIER) and Translational Research Investigating Underlying Disparities in Acute Myocardial Infarction Patients' Health Status (TRIUMPH) registries.

BACKGROUND: Whereas statins are considered the cornerstone of prevention after acute myocardial infarction (AMI), concerns about worsening depression in association with their use have been raised. METHODS: Using data from 2 prospective AMI registries (PREMIER and TRIUMPH), we examined the change in depressive symptoms from baseline and at 1, 6 and 12 months among statin-naïve patients who were and were not discharged on a statin. Depressive symptoms were assessed with the 8-item Patient Health Questionnaire (PHQ-8). Within-group change in PHQ-8 scores from baseline to each follow-up period was assessed using paired t tests. A repeated-measures propensity-matched analysis examined whether changes in PHQ-8 scores from baseline were different between statin-treated and statin-untreated patients. RESULTS: Of 3,675 patients not previously treated with statins, 3,050 (83%) were discharged on a statin and 625 (17%) were not. Scores of PHQ-8 in the statin group decreased from baseline by a mean (± SD) of 0.9 (± 5.1), 1.2 (± 5), and 1.1 (± 5.1) at 1, 6, and 12 months, respectively. Corresponding changes in the nonstatin group were 0.9 (± 5.2), 1.3 (± 5.1), and 1.5 (± 5.8), respectively (P < .0001 for all comparisons). After propensity matching, 451 patients not discharged on statins with 1,240 patients discharged on statins, the mean change in PHQ-8 scores between baseline and the 3 follow-up time points was not significantly different between groups (mean between-group difference at 1 month: -0.13, 95% CI [-0.69 to 0.43], P = .65; at 6 months: -0.07, 95% CI [-0.66 to 0.52], P = .82; and at 12 months: -0.05, 95% CI [-0.67 to 0.58], P = .88). CONCLUSIONS: Initiation of statins after AMI was not associated with worsening depression.

Resting perfusion MPI-SPECT combined with cardiac 123I-mIBG sympathetic innervation imaging improves prediction of arrhythmic events in non-ischemic cardiomyopathy patients: sub-study from the ADMIRE-HF trial.

BACKGROUND: Delayed Iodine-123 meta-iodobenzylguanidine heart/mediastinum (H/M) uptake ratio predicted arrhythmic events in patients with heart failure (HF) and significant left ventricular dysfunction in ADMIRE-HF. We tested the hypothesis that resting perfusion defects on MPI-SPECT, representing scar, would further risk stratify patients beyond H/M ratio in the prediction of ventricular arrhythmic events in both ischemic (ICM) and non-ischemic cardiomyopathy (NICM) patients. METHODS: Patients from the ADMIRE-HF database were classified as ICM and NICM and were stratified by delayed H/M ratio (<1.6/≥1.6) and by summed rest score (SRS) (≤8/>8) on MPI-SPECT. The entire cohort was also classified as high risk (H/M <1.6, SRS >8) and low risk (H/M ≥1.6, SRS ≤8). Scores were from visual interpretation of individual and derived consensus (average) reads per ASNC guidelines. RESULTS: There were 612 (66%) ICM and 317 (34%) NICM patients. ICM patients had higher mean SRS than NICM patients (25 ± 13 vs 12 ± 10). Sixty-three arrhythmic events occurred over a median follow-up of 17 months. SRS had incremental predictive value among NICM patients with low H/M ratio (<1.6). There was no risk stratification in patients with ICM. Multivariable analysis for NICM with H/M ratio <1.6 demonstrated SRS score >8 as the only independent predictor of arrhythmic events (hazard ratio 3.3, 95% CI 1.1-9.8, P = .03). Patients classified in high-risk subgroup had statistically significant increased risk of arrhythmic events (hazard ratio 2.080, 95% CI 1.112-3.894, P = .022). There was only one event in low-risk subgroup with a trend towards lower risk of arrhythmic events (P = .07). CONCLUSION: Resting perfusion defects provide independent risk stratification in addition to Iodine-123 meta-iodobenzylguanidine sympathetic innervation imaging in predicting arrhythmic events in patients with NICM and HF. High and potentially low-risk groups for arrhythmic events can be identified based on the severity of resting perfusion defect score and H/M ratio.

Red yeast rice for dysipidemia.

Red yeast rice is an ancient Chinese food product that contains monacolins, chemical substances that are similar to statins in their mechanisms of action and lipid lowering properties. Several studies have found red yeast rice to be moderately effective at improving the lipid profile, particularly for lowering the low-density lipoprotein cholesterol levels. One large randomized controlled study from China found that red yeast rice significantly improved risk of major adverse cardiovascular events and overall survival in patients following myocardial infarction. Thus, red yeast rice is a potentially useful over-the-counter cholesterol-lowering agent. However, many red yeast rice formulations are non-standardized and unregulated food supplements, and there is a need for further research and regulation of production.

Management of Patients With Tricuspid Valve Endocarditis and Ongoing Intravenous Drug Abuse: Less Is More.

Right-sided infective endocarditis in patients with intravenous drug abuse portends a worse prognosis. Data on optimal management strategy in this situation are scarce. We describe outcomes of 2 different treatment strategies, including a patient treated conservatively with favorable intermediate-term results and another who was treated surgically and developed recurrent endocarditis. (Level of Difficulty: Intermediate.).

Outcomes of Transcatheter Aortic Valve Replacement in the United Arab Emirates: Real-world, Single-centre Experience from an Emerging Programme.

Background: Data on outcomes of transcatheter aortic valve replacement (TAVR) in the Middle East, particularly in the United Arab Emirates (UAE), are limited. Whether centres with a low volume of patients requiring the procedure can achieve similar outcomes as those reported in pivotal clinical trials remains unclear. This study evaluates procedural outcomes of patients undergoing TAVR in a newly established programme in the UAE. Methods: Procedural outcomes of consecutive patients who underwent transfemoral TAVR at a single centre in the UAE between January 2016 and November 2021 were compared with those at centres in the lowest quartile (Q1) of procedural volume in the Transcatheter Valve Therapy Registry, which covers centres in the US. Results: Among the 183 patients included in the study, the median age was 76 years (interquartile range [IQR] 71-82), and 42.1% of patients were women, with a median Society of Thoracic Surgeons predicted risk of mortality score of 4.6 (IQR 2.9-7.5). Most of the patients (93.3%) received a balloon-expandable valve. All-cause death within 30 days, stroke and major vascular complications occurred in 0.6%, 0.6% and 2.2% of patients, respectively, compared with 3.1%, 2.2% and 4% in patients treated at Q1 hospitals. Conclusion: Patients undergoing transfemoral TAVR at an emerging centre in the Middle East had favourable outcomes compared with those performed at Q1 hospitals in the US. These findings suggest that careful patient selection for TAVR is critical and may help optimise patient outcomes, especially when procedural volumes are low.

Early Identification and Management of Heart Failure in Patients with Diabetes Mellitus in the United Arab Emirates: A Call to Action.

Heart failure (HF) is a common and serious complication of diabetes mellitus (DM) that remains widely under-recognized. Multidisciplinary management protocols for patients with concurrent DM and HF are not widely utilized in the Middle East/Gulf region, particularly in the United Arab Emirates. Since early identification of patients with DM and HF will likely lead to initiation of therapies known to prevent adverse cardiovascular events and subsequently improve patient prognosis, we aim to highlight the importance of early recognition of HF in diabetic patients. We will also describe existing management challenges in the region, especially the lack of multidisciplinary care and emphasize the role of newer anti-diabetic therapies in preventing and treating HF. Most importantly, this call-to-action proposes a collaborative approach to the care of diabetic patients with HF involving primary care physicians, endocrinologists, and cardiologists.

Management of acute aortic services during the COVID-19 pandemic: a retrospective cohort study from the Middle East.

COVID-19 created a challenging situation for cardiac surgery and associated acute care programs around the world. While non-urgent cases might be postponed, operating on life-threatening conditions, including type A aortic dissection (TAAD), must be sustained despite the ongoing pandemic. Therefore, the authors investigated the impact of the COVID-19 pandemic on their urgent aortic program. Methods: The authors included consecutive patients presenting with TAAD (n=36) in the years 2019 and 2020 [pre-pandemic period (2019; n=16) and the pandemic era (2020; n=20)] at a tertiary care centre. Patient characteristics, TAAD presenting symptoms, operative techniques, postoperative outcomes, and length of stay were determined retrospectively using chart review and were compared between both years. Results: An increase occurred in the absolute number of TAAD referrals during the pandemic era. Patients were featured by younger age of presentation (pre-pandemic group: 47.6±18.7, and the pandemic group: 50.6±16.2 years, P=0.6) in contrast to Western data but showed similar male predominance (4:1) in both groups. There was no statistical difference in baseline comorbidities between the groups. Length of hospital stay [20 (10.8-56) vs. 14.5 (8.5-53.3) days, P=0.5] and intensive care unit stay [5 (2.3-14.5) vs. 5 (3.3-9.3) days, P=0.4] were comparable between both groups. Low rates of postoperative complications were registered in both groups with no significant between-group difference. There was no significant difference in the rates of in-hospital mortality between both groups [12.5% (2) vs. 10% (2), P=0.93]. Conclusions: Compared with the pre-pandemic era (2019), there was no difference in resource utilisation and clinical outcomes of patients presenting with TAAD during the first year of COVID-19 pandemic (2020). Structural departmental re-configuration and optimal personal protective equipment utilisation warrant maintained satisfactory outcomes in critical healthcare scenarios. Future studies are required to further investigate aortic care delivery during such challenging pandemics.

From Clinical Clues to Final Diagnosis: The Return of Detective Work to Clinical Medicine in Cardiac Amyloidosis.

Cardiac amyloidosis is frequently misdiagnosed, denying patients the opportunity for timely and appropriate management of the disease. The purpose of this review and case studies is to raise awareness of the diagnostic "red flags" associated with cardiac amyloidosis and the currently available non-invasive strategies for diagnosis. The review focuses on the identification of one of the two main types of cardiac amyloidosis, transthyretin amyloid cardiomyopathy, and non-invasive tools to distinguish this from light-chain amyloidosis. A diagnostic algorithm centered around the use of non-invasive imaging and laboratory analysis is presented. The algorithm generates four differential diagnoses for patients presenting with signs and symptoms consistent with cardiac amyloidosis. Case examples are presented, representing the four potential outcomes of diagnosis using the algorithm. The review provides a guide on how to recognize the often-overlooked presentations of this disease in clinical practice. Non-invasive imaging techniques and diagnostic tools that do not require the involvement of a specialty center have allowed for the improved diagnosis of cardiac amyloidosis. Timely diagnosis of this life-threatening disease is essential for optimal management and it is imperative that clinicians have a high index of suspicion for patients presenting with "red flag" symptoms.

Comparison of the Effect of Catheter Ablation for Atrial Fibrillation on All-Cause Hospitalization in Patients With Versus Without Heart Failure (from the Nationwide Readmission Database).

Catheter ablation (CA) is associated with reduced arrhythmia recurrence and improved quality of life in patients with atrial fibrillation (AF). Heart failure (HF) is common in patients with AF and is associated with a high hospitalization burden. The real-world association between CA and rates of subsequent hospitalization in patients with AF and HF has not been well studied. Patients who underwent CA for AF during the middle 4 months of each year 2010 to 2015 were identified using the Nationwide Readmission Database. Patients were grouped according to the HF status and HF patients were stratified to reduced versus preserved ejection fraction (EF) using ICD-9 codes. Rates of all-cause hospitalization 120 days before and after index admission were compared using the McNemar's test, before and after matching for baseline characteristics. A total of 10,966 patients met inclusion criteria, including 1,950 with HF. In the HF group, all-cause hospitalization rates changed from 45.8% before CA to 33.2% after (p <0.001). Corresponding rates for non-HF patients were 23.8% and 19.7% (p< 0.001) with a greater relative reduction in hospitalizations seen in the HF group (27.5% vs 17.2%; p value <0.001). The difference in relative reduction persisted after adjustment by propensity score matching. The relative reduction in hospitalization rates was similar in HF patients with reduced and preserved EF with 25.2% and 28.5%, respectively. In conclusion, CA for AF was followed by a significant reduction in all-cause hospitalization rates. Patients with HF, regardless of EF, showed a greater reduction in admissions.

Temporal trends in test utilization and prevalence of ischaemia with positron emission tomography myocardial perfusion imaging.

AIMS: To examine whether test utilization and prevalence of ischemia with positron emission tomography (PET) myocardial perfusion imaging (MPI) follow the previously described trends with single photon computed tomography (SPECT). METHODS AND RESULTS: MPI studies performed between January 2003 and December 2017 were identified. Number of PET and SPECT MPI studies performed per year was determined. Trends in the proportion of studies showing any ischaemia (>0%) with both modalities were compared before and after adjusting for baseline differences in patient characteristics using propensity scores. Interaction between imaging modality and year of testing was examined using modified Poisson regression. A total of 156 244 MPI studies were performed (30% PET and 70% SPECT). Between 2003 and 2017, the number of PET studies increased from 18 to 61 studies/1000 patient encounters, while SPECT volumes declined from 169 to 34/1000 patient encounters (P < 0.001 for within-group comparisons). The prevalence of any ischaemia in SPECT-tested patients declined from 53.9% to 28.3% between 2003 and 2017, whereas ischaemia prevalence in PET-tested patients declined from 57.2% to 38.2% (P < 0.001 for within-modality comparisons), with more PET studies showing ischaemia compared to SPECT [relative risk (RR) 1.44, 95% confidence interval (CI) 1.42-1.47; P < 0.001]. After propensity score matching of 26 066 patients tested with SPECT with 26 066 patients tested with PET, the between-modality difference in ischaemia prevalence was significantly attenuated, with a slightly higher overall likelihood of detecting ischaemia with PET compared to SPECT (RR 1.08, 95% CI 1.05-1.11; P < 0.001). CONCLUSIONS: Utilization of PET MPI at a large-volume referral centre increased significantly between 2003 and 2017. Despite a significant decrease in the prevalence of ischaemia with SPECT and PET during the same period, the decline was less with PET, perhaps related to baseline risk of tested patients.