Sex-Specific Stress Perfusion Cardiac Magnetic Resonance Imaging in Suspected Ischemic Heart Disease: Insights From SPINS Retrospective Registry.

BACKGROUND: Cardiovascular disease (CVD) remains the leading cause of mortality in women, but current noninvasive cardiac imaging techniques have sex-specific limitations. OBJECTIVES: In this study, the authors sought to investigate the effect of sex on the prognostic utility and downstream invasive revascularization and costs of stress perfusion cardiac magnetic resonance (CMR) for suspected CVD. METHODS: Sex-specific prognostic performance was evaluated in a 2,349-patient multicenter SPINS (Stress CMR Perfusion Imaging in the United States [SPINS] Study) Registry. The primary outcome measure was a composite of cardiovascular death and nonfatal myocardial infarction; secondary outcomes were hospitalization for unstable angina or heart failure, and late unplanned coronary artery bypass grafting. RESULTS: SPINS included 1,104 women (47% of cohort); women had higher prevalence of chest pain (62% vs 50%; P < 0.0001) but lower use of medical therapies. At the 5.4-year median follow-up, women with normal stress CMR had a low annualized rate of primary composite outcome similar to men (0.54%/y vs 0.75%/y, respectively; P = NS). In contrast, women with abnormal CMR were at higher risk for both primary (3.74%/y vs 0.54%/y; P < 0.0001) and secondary (9.8%/y vs 1.6%/y; P < 0.0001) outcomes compared with women with normal CMR. Abnormal stress CMR was an independent predictor for the primary (HR: 2.64 [95% CI: 1.20-5.90]; P = 0.02) and secondary (HR: 2.09 [95% CI: 1.43-3.08]; P < 0.0001) outcome measures. There was no effect modification for sex. Women had lower rates of invasive coronary angiography (3.6% vs 7.3%; P = 0.0001) and downstream costs ($114 vs $171; P = 0.001) at 90 days following CMR. There was no effect of sex on diagnostic image quality. CONCLUSIONS: Stress CMR demonstrated excellent prognostic performance with lower rates of invasive coronary angiography referral in women. Stress CMR should be considered as a first-line noninvasive imaging tool for the evaluation of women. (Stress CMR Perfusion Imaging in the United States [SPINS] Study [SPINS]; NCT03192891).

The Evolving Trends in Infective Endocarditis and Determinants of Mortality: a 10-year Experience From a Tertiary Care Epicenter.

The epidemiology of infective endocarditis (IE) continues to evolve in areas affected by the opioid epidemic. Understanding the demographics of the disease allows us to better tailor therapy towards this at-risk population. This was an observational study of adults (age ≥ 18) admitted to the University of Kentucky hospital with IE between January 2009 and December 2018. 1,255 patients were included in the final analysis. The mean age was 42 years, 45% were female and injection drug use was seen in 66% of patients. On multivariable analysis, higher Charlson comorbidity indices, left sided, and multivalve involvement were associated with increased mortality, whereas surgical intervention demonstrated a trend towards lower mortality. Our results highlight the alarming increase in injection drug use related IE and the high mortality rates despite therapeutic advances. Patients with left sided IE, multivalve involvement and a higher Charlson comorbidity index had decreased survival.

Autologous CD133 + Cells and Laser Revascularization in patients with severe Ischemic Cardiomyopathy.

OBJECTIVE: We tested the hypothesis that targeted TMLR combined with intramyocardial injection of autologous CD 133+ progenitor cells is safe and feasible in patients with chronic ischemic cardiomyopathy (ICM) and no revascularization options. METHODS: Eight male patients (age 62 ± 2.4 years) with multivessel severe ischemic heart disease and no revascularization options were enrolled. Autologous CD 133 + endothelial progenitor cells were derived and purified from the bone marrow on the day of surgery using the clinical-grade closed CliniMACS system. Using a lateral thoracotomy approach, TMLR was performed, followed by transmyocardial transplantation of purified CD133 + cells (mean number of transplanted cells: 12.5 × 106) in the region surrounding the TMLR sites. These sites were selected based on ischemia on pre-procedure perfusion imaging. We performed clinical and myocardial perfusion imaging pre-procedure and then at 6- and 12-month follow-up. RESULTS: No major complications or death occurred during the procedure or during the peri-operative hospital stay. One patient died of cardiac cause 6 months post-procedure. There was a reported short-term improvement in anginal and heart failure symptoms and a modest reduction in the ischemic score as assessed by perfusion imaging. CONCLUSIONS: Our phase 1 clinical study examining the combination therapy of targeted transmyocardial laser revascularization therapy and autologous CD133 + endothelial progenitor cells in patients with chronic ICM and no revascularization options demonstrates the feasibility and short-term safety of this combined approach and warrants future larger phase 2 randomized clinical studies.

Highlights of the Virtual Society for Cardiovascular Magnetic Resonance 2022 Scientific Conference: CMR: improving cardiovascular care around the world.

The 25th Society for Cardiovascular Magnetic Resonance (SCMR) Annual Scientific Sessions saw 1524 registered participants from more than 50 countries attending the meeting virtually. Supporting the theme "CMR: Improving Cardiovascular Care Around the World", the meeting included 179 invited talks, 52 sessions including 3 plenary sessions, 2 keynote talks, and a total of 93 cases and 416 posters. The sessions were designed so as to showcase the multifaceted role of cardiovascular magnetic resonance (CMR) in identifying and prognosticating various myocardial pathologies. Additionally, various social networking sessions as well as fun activities were organized. The major areas of focus for the future are likely to be rapid efficient and high value CMR exams, automated and quantitative acquisition and post-processing using artificial intelligence and machine learning, multi-contrast imaging and advanced vascular imaging including 4D flow.

Reproducibility of Systolic Strain in Mice Using Cardiac Magnetic Resonance Feature Tracking of Black-Blood Cine Images.

PURPOSE: Mouse models are widely utilized to enhance our understanding of cardiac disease. The goal of this study is to investigate the reproducibility of strain parameters that were measured in mice using cardiac magnetic resonance (CMR) feature-tracking (CMR42, Canada). METHODS: We retrospectively analyzed black-blood CMR datasets from thirteen C57BL/6 B6.SJL-CD45.1 mice (N = 10 female, N = 3 male) that were imaged previously. The circumferential, longitudinal, and radial (Ecc, Ell, and Err, respectively) parameters of strain were measured in the mid-ventricular region of the left ventricle. Intraobserver and interobserver reproducibility were assessed for both the end-systolic (ES) and peak strain. RESULTS: The ES strain had larger intraclass correlation coefficient (ICC) values when compared to peak strain, for both the intraobserver and interobserver reproducibility studies. Specifically, the intraobserver study showed excellent reproducibility for all three ES strain parameters, namely, Ecc (ICC 0.95, 95% CI 0.83-0.98), Ell (ICC 0.90, 95% CI 0.59-0.97), and Err (ICC 0.92, 95% CI 0.73-0.97). This was also the case for the interobserver study, namely, Ecc (ICC 0.92, 95% CI 0.60-0.98), Ell (ICC 0.76, 95% CI 0.33-0.93), and Err (ICC 0.93, 95% CI 0.68-0.98). Additionally, the coefficient of variation values were all < 10%. CONCLUSION: The results of this preliminary study showed excellent reproducibility for all ES strain parameters, with good to excellent reproducibility for the peak strain parameters. Moreover, all ES strain parameters had larger ICC values than the peak strain. In general, these results imply that feature-tracking with CMR42 software and black-blood cine images can be reliably used to assess strain patterns in mice.

Adipocyte-Derived Serum Amyloid A Promotes Angiotensin II-Induced Abdominal Aortic Aneurysms in Obese C57BL/6J Mice.

BACKGROUND: Obesity increases the risk for human abdominal aortic aneurysms (AAAs) and enhances Ang II (angiotensin II)-induced AAA formation in C57BL/6J mice. Obesity is also associated with increases in perivascular fat that expresses proinflammatory markers including SAA (serum amyloid A). We previously reported that deficiency of SAA significantly reduces Ang II-induced inflammation and AAA in hyperlipidemic apoE-deficient mice. In this study. we investigated whether adipose tissue-derived SAA plays a role in Ang II-induced AAA in obese C57BL/6J mice. METHODS: The development of AAA was compared between male C57BL/6J mice (wild type), C57BL/6J mice lacking SAA1.1, SAA2.1, and SAA3 (TKO); and TKO mice harboring a doxycycline-inducible, adipocyte-specific SAA1.1 transgene (TKO-Tgfat; SAA expressed only in fat). All mice were fed an obesogenic diet and doxycycline to induce SAA transgene expression and infused with Ang II to induce AAA. RESULTS: In response to Ang II infusion, SAA expression was significantly increased in perivascular fat of obese C57BL/6J mice. Maximal luminal diameters of the abdominal aorta were determined by ultrasound before and after Ang II infusion, which indicated a significant increase in aortic luminal diameters in wild type and TKO-TGfat mice but not in TKO mice. Adipocyte-specific SAA expression was associated with MMP (matrix metalloproteinase) activity and macrophage infiltration in abdominal aortas of Ang II-infused obese mice. CONCLUSIONS: We demonstrate for the first time that SAA deficiency protects obese C57BL/6J mice from Ang II-induced AAA. SAA expression only in adipocytes is sufficient to cause AAA in obese mice infused with Ang II.

Prognostic Value of Stress Cardiac Magnetic Resonance in Patients With Known Coronary Artery Disease.

OBJECTIVES: This study sought to determine whether stress cardiac magnetic resonance (CMR) provides clinically relevant risk reclassification in patients with known coronary artery disease (CAD) in a multicenter setting in the United States. BACKGROUND: Despite improvements in medical therapy and coronary revascularization, patients with previous CAD account for a disproportionately large portion of CV events and pose a challenge for noninvasive stress testing. METHODS: From the Stress Perfusion Imaging in the United States (SPINS) registry, we identified consecutive patients with documented CAD who were referred to stress CMR for evaluation of myocardial ischemia. The primary outcome was nonfatal myocardial infarction (MI) or cardiovascular (CV) death. Major adverse CV events (MACE) included MI/CV death, hospitalization for heart failure or unstable angina, and late unplanned coronary artery bypass graft. The prognostic association and net reclassification improvement by ischemia for MI/CV death were determined. RESULTS: Out of 755 patients (age 64 ± 11 years, 64% male), we observed 97 MI/CV deaths and 210 MACE over a median follow-up of 5.3 years. Presence of ischemia demonstrated a significant association with MI/CV death (HR: 2.30; 95% CI: 1.54-3.44; P < 0.001) and MACE (HR: 2.24 ([95% CI: 1.69-2.95; P < 0.001). In a multivariate model adjusted for CV risk factors, ischemia maintained strong association with MI/CV death (HR: 1.84; 95% CI: 1.17-2.88; P = 0.008) and MACE (HR: 1.77; 95% CI: 1.31-2.40; P < 0.001) and reclassified 95% of patients at intermediate pretest risk (62% to low risk, 33% to high risk) with corresponding changes in the observed event rates of 1.4% and 5.3% per year for low and high post-test risk, respectively. CONCLUSIONS: In a multicenter cohort of patients with known CAD, CMR-assessed ischemia was strongly associated with MI/CV death and reclassified patient risk beyond CV risk factors, especially in those considered to be at intermediate risk. Absence of ischemia was associated with a <2% annual rate of MI/CV death. (Stress CMR Perfusion Imaging in the United States [SPINS] Study; NCT03192891).

ST-Segment Elevation in a Patient With Nausea, Vomiting, and Intracerebral Hemorrhage.

A 60-year-old man who presented with nausea, vomiting, and intracerebral hemorrhage developed inferior ST-segment elevation and angina. Coronary angiography showed no coronary obstruction. The patient was found to have a small bowel obstruction causing superior translocation of the heart. Relief of obstruction caused immediate resolution of electrocardiographic changes and symptoms. (Level of Difficulty: Beginner.).

Regional end-systolic circumferential strain demonstrates compensatory segmental contractile function in patients with ST-segment elevation myocardial infarction.

Myocardial strain has shown tremendous promise as a potential diagnostic tool for characterizing ventricular function. With regards to myocardial infarction, global circumferential strain (CS) can be used to assess overall function, while regional CS can identify local alterations in contractility. Currently, there is a lack of data related to regional strain in patients with ST-segment elevation myocardial infarction (STEMI). Thus, the goal of this study was to quantify regional strain patterns in STEMI and normal control patients, measuring both peak CS and end-systolic (ES) CS in the mid-ventricular region. This was done by conducting cardiac magnetic resonance (CMR) imaging acutely after STEMI patients underwent primary percutaneous coronary intervention. The CMR datasets were then analyzed using feature-tracking of the cine images. The patients were broken into three groups: (1) control patients (N = 18), (2) STEMI patients with ejection fraction (EF) ≥ 50% (N = 20), and (3) STEMI patients with EF < 50% (N = 20). The key result of the analysis was that ES CS detected a significant increase in the magnitude of strain in the non-infarcted tissue of STEMI patients with EF ≥ 50% when compared to STEMI patients with EF < 50%, whereas peak CS did not detect any differences. This implies that the tissue in this region is contracting more strongly compared to non-infarcted tissue in STEMI patients with EF < 50%. Thus, regional ES CS could potentially be utilized as a diagnostic tool for assessing STEMI patients, by detecting regional changes in contractility after PCI, which could assist in treatment planning.

ACR Appropriateness Criteria® Syncope.

Syncope and presyncope lead to well over one million emergency room visits in the United States each year. Elucidating the cause of syncope or presyncope, which are grouped together given similar etiologies and outcomes, can be exceedingly difficult given the diverse etiologies. This becomes more challenging as some causes, such as vasovagal syncope, are relatively innocuous while others, such as cardiac-related syncope, carry a significant increased risk of death. While the mainstay of syncope and presyncope assessment is a detailed history and physical examination, imaging can play a role in certain situations. In patients where a cardiovascular etiology is suspected based on the appropriate history, physical examination, and ECG findings, resting transthoracic echocardiography is usually considered appropriate for the initial imaging. While no imaging studies are considered usually appropriate when there is a low probability of cardiac or neurologic pathology, chest radiography may be appropriate in certain clinical situations. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Infective endocarditis in pregnancy from 2009 to 2019: the consequences of injection drug use.

BACKGROUND: Endocarditis during pregnancy carries a maternal mortality of up to 30%, but prior publications do not reflect the current opioid epidemic. CASE PRESENTATIONS: We reviewed our institution's infective endocarditis registry from 2009 to 2019 and identified 19 females with endocarditis during pregnancy in order to compare our contemporary outcomes with historical reports. In our cohort, intravenous drug use was reported in all cases, and the most common pathogen was Staphylococcus (74%) followed by Serratia (13%). The tricuspid valve was involved in 18 (95%) patients, and contrary to prior reports, all but two patients were managed conservatively with antibiotics alone. Maternal and infant mortality (5% and 0%, respectively) were lower in our cohort compared to all previous reviews. CONCLUSION: We conclude that the better outcomes seen in this report are likely due to the younger age of the patients and the more frequent right-sided valvular involvement. SUMMARY: This review highlights contemporary outcomes in endocarditis during pregnancy. We review historical case reports in light of the opioid epidemic. We observed more Staphylococcus, more right-sided valvular involvement, and more conservative management as well as improved maternal and foetal mortality.

Donor Pulmonary Vein Anomalies: What's in Your Toolbox?

Pulmonary vein anomalies are often unrecognized during donor lung procurement. Consequently, they are at high risk for injury, and this leaves the implanting surgeon with an unpleasant surprise. An innovative approach can help resolve the situation. We wish to highlight our experience with an anomalous left upper pulmonary vein and describe a novel reconstruction technique.

Stress CMR in patients with obesity: insights from the Stress CMR Perfusion Imaging in the United States (SPINS) registry.

AIMS: Non-invasive assessment and risk stratification of coronary artery disease in patients with large body habitus is challenging. We aim to examine whether body mass index (BMI) modifies the prognostic value and diagnostic utility of stress cardiac magnetic resonance imaging (CMR) in a multicentre registry. METHODS AND RESULTS: The SPINS Registry enrolled consecutive intermediate-risk patients who presented with a clinical indication for stress CMR in the USA between 2008 and 2013. Baseline demographic data including BMI, CMR indices, and ratings of study quality were collected. Primary outcome was defined by a composite of cardiovascular death and non-fatal myocardial infarction. Of the 2345 patients with available BMI included in the SPINS cohort, 1177 (50%) met criteria for obesity (BMI ≥ 30) with 531 (23%) at or above Class 2 obesity (BMI ≥ 35). In all BMI categories, >95% of studies were of diagnostic quality for cine, perfusion, and late gadolinium enhancement (LGE) sequences. At a median follow-up of 5.4 years, those without ischaemia and LGE experienced a low annual rate of hard events (<1%), across all BMI strata. In patients with obesity, both ischaemia [hazard ratio (HR): 2.14; 95% confidence interval (CI): 1.30-3.50; P = 0.003] and LGE (HR: 3.09; 95% CI: 1.83-5.22; P < 0.001) maintained strong adjusted association with the primary outcome in a multivariable Cox regression model. Downstream referral rates to coronary angiography, revascularization, and cost of care spent on ischaemia testing did not significantly differ within the BMI categories. CONCLUSION: In this large multicentre registry, elevated BMI did not negatively impact the diagnostic quality and the effectiveness of risk stratification of patients referred for stress CMR.

Prognostic Value of Stress CMR Perfusion Imaging in Patients With Reduced Left Ventricular Function.

OBJECTIVES: The aim of this study was to investigate the prognostic value of stress cardiac magnetic resonance imaging (CMR) in patients with reduced left ventricular (LV) systolic function. BACKGROUND: Patients with ischemic cardiomyopathy are at risk from both myocardial ischemia and heart failure. Invasive testing is often used as the first-line investigation, and there is limited evidence as to whether stress testing can effectively provide risk stratification. METHODS: In this substudy of a multicenter registry from 13 U.S. centers, patients with reduced LV ejection fraction (<50%), referred for stress CMR for suspected myocardial ischemia, were included. The primary outcome was cardiovascular death or nonfatal myocardial infarction. The secondary outcome was a composite of cardiovascular death, nonfatal myocardial infarction, hospitalization for unstable angina or congestive heart failure, and unplanned late coronary artery bypass graft surgery. RESULTS: Among 582 patients (mean age 62 ± 12 years, 34% women), 40% had a history of congestive heart failure, and the median LV ejection fraction was 39% (interquartile range: 28% to 45%). At median follow-up of 5.0 years, 97 patients had experienced the primary outcome, and 182 patients had experienced the secondary outcome. Patients with no CMR evidence of ischemia or late gadolinium enhancement (LGE) experienced an annual primary outcome event rate of 1.1%. The presence of ischemia, LGE, or both was associated with higher event rates. In a multivariate model adjusted for clinical covariates, ischemia and LGE were independent predictors of the primary (hazard ratio [HR]: 2.63; 95% confidence interval [CI]: 1.68 to 4.14; p < 0.001; and HR: 1.86; 95% CI: 1.05 to 3.29; p = 0.03) and secondary (HR: 2.14; 95% CI: 1.55 to 2.95; p < 0.001; and HR 1.70; 95% CI: 1.16 to 2.49; p = 0.007) outcomes. The addition of ischemia and LGE led to improved model discrimination for the primary outcome (change in C statistic from 0.715 to 0.765; p = 0.02). The presence and extent of ischemia were associated with higher rates of use of downstream coronary angiography, revascularization, and cost of care spent on ischemia testing. CONCLUSIONS: Stress CMR was effective in risk-stratifying patients with reduced LV ejection fractions. (Stress CMR Perfusion Imaging in the United States [SPINS] Study; NCT03192891).

Imaging of Clinically Unrecognized Myocardial Fibrosis in Patients With Suspected Coronary Artery Disease.

BACKGROUND: Stress cardiac magnetic resonance (CMR) provides accurate assessment of both myocardial infarction (MI) and ischemia. OBJECTIVES: This study aimed to evaluate the incremental prognostic value of unrecognized myocardial infarction (UMI), detected during assessment of coronary artery disease (CAD) by stress CMR, beyond cardiac function and ischemia. METHODS: In the multicenter SPINS (Stress CMR Perfusion Imaging in the United States) study, 2,349 consecutive patients (63 ± 11 years of age, 53% were male) with suspected CAD were assessed by stress CMR and followed over a median of 5.4 years. UMI was defined as the presence of late gadolinium enhancement consistent with MI in the absence of medical history of MI. This study investigated the association of UMI with all-cause mortality and nonfatal MI (death and/or MI), and major adverse cardiac events (MACE). RESULTS: UMI was detected in 347 patients (14.8%) and clinically recognized myocardial infarction (RMI) in 358 patients (15.2%). Compared with patients with RMI, patients with UMI had a similar burden of cardiovascular risk factors, but significantly lower left ventricular ejection fraction (p < 0.001) and lower rates of guideline-directed medical therapies, including aspirin (p < 0.001), statin (p < 0.001), and beta-blockers (p = 0.002). During follow-up, 328 deaths and/or MIs and 528 MACE occurred. In univariate analysis, UMI and RMI were strongly associated with death and/or MI (UMI: hazard ratio [HR]: 2.15; 95% confidence interval [CI]: 1.63 to 2.83; p < 0.001; RMI: HR: 2.45; 95% CI: 1.89 to 3.18) and MACE. Compared with patients with RMI, patients with UMI presented an increased risk for heart failure hospitalization (UMI vs. RMI: HR: 2.60; 95% CI: 1.48 to 4.58; p < 0.001). In a multivariate model including ischemia and left ventricular ejection fraction, UMI and RMI maintained robust prognostic association with death and/or MI (UMI: HR: 1.82; 95% CI: 1.37 to 2.42; p < 0.001; RMI: HR: 1.54; 95% CI: 1.14 to 2.09) and MACE. CONCLUSIONS: In a multicenter cohort of patients with suspected CAD, presence of UMI or RMI portended an equally significant risk for death and/or MI, independently of the presence of ischemia. Compared with RMI patients, those with UMI were less likely to receive guideline-directed medical therapies and presented an increased risk for heart failure hospitalization that warrants further study. (Stress CMR Perfusion Imaging in the United States [SPINS]; NCT03192891).

Evaluation of Stress Cardiac Magnetic Resonance Imaging in Risk Reclassification of Patients With Suspected Coronary Artery Disease.

Importance: The role of stress cardiac magnetic resonance (CMR) imaging in clinical decision-making by reclassification of risk across American College of Cardiology/American Heart Association guideline-recommended categories has not been established. Objective: To examine the utility of stress CMR imaging for risk reclassification in patients without a history of coronary artery disease (CAD) who presented with suspected myocardial ischemia. Design, Setting, and Participants: A retrospective, multicenter cohort study with median follow-up of 5.4 years (interquartile range, 4.6-6.9) was conducted at 13 centers across 11 US states. Participants included 1698 consecutive patients aged 35 to 85 years with 2 or more coronary risk factors but no history of CAD who presented with suspected myocardial ischemia to undergo stress CMR imaging. The study was conducted from February 18, 2019, to March 1, 2020. Main Outcomes and Measures: Cardiovascular (CV) death and nonfatal myocardial infarction (MI). Major adverse CV events (MACE) including CV death, nonfatal MI, hospitalization for heart failure or unstable angina, and late, unplanned coronary artery bypass graft surgery. Results: Of the 1698 patients, 873 were men (51.4%); mean (SD) age was 62 (11) years, accounting for 67 CV death/nonfatal MIs and 190 MACE. Clinical models of pretest risk were constructed and patients were categorized using guideline-based categories of low (<1% per year), intermediate (1%-3% per year), and high (>3% year) risk. Stress CMR imaging provided risk reclassification across all baseline models. For CV death/nonfatal MI, adding stress CMR-assessed left ventricular ejection fraction, presence of ischemia, and late gadolinium enhancement to a model incorporating the validated CAD Consortium score, hypertension, smoking, and diabetes provided significant net reclassification improvement of 0.266 (95% CI, 0.091-0.441) and C statistic improvement of 0.086 (95% CI, 0.022-0.149). Stress CMR imaging reclassified 60.3% of patients in the intermediate pretest risk category (52.4% reclassified as low risk and 7.9% as high risk) with corresponding changes in the observed event rates of 0.6% per year for low posttest risk and 4.9% per year for high posttest risk. For MACE, stress CMR imaging further provided significant net reclassification improvement (0.361; 95% CI, 0.255-0.468) and C statistic improvement (0.092; 95% CI, 0.054-0.131), and reclassified 59.9% of patients in the intermediate pretest risk group (48.7% reclassified as low risk and 11.2% as high risk). Conclusions and Relevance: In this multicenter cohort of patients with no history of CAD presenting with suspected myocardial ischemia, stress CMR imaging reclassified patient risk across guideline-based risk categories, beyond clinical risk factors. The findings of this study support the value of stress CMR imaging for clinical decision-making, especially in patients at intermediate risk for CV death and nonfatal MI.