Gadolinium-based contrast agents have expanded the diagnostic usefulness and capability of magnetic resonance imaging. Despite their highly favorable safety profile, these agents have been associated with nephrogenic systemic fibrosis in a small number of patients who have advanced kidney disease. Recently, trace amounts of gadolinium deposition in the brain and other organs have been reported after contrast exposure, even in patients with normal renal function. In this review, we provide a brief overview of recent updates and discuss typical clinical situations related to the use of gadolinium-based contrast agents.

Preventing sudden cardiac death (SCD) in athletes is a primary duty of sports cardiologists. Current recommendations for detecting high-risk cardiovascular conditions (hr-CVCs) are history and physical examination (H&P)-based. We discuss the effectiveness of H&P-based screening versus more-modern and accurate methods. In this position paper, we review current authoritative statements and suggest a novel alternative: screening MRI (s-MRI), supported by evidence from a preliminary population-based study (completed in 2018), and a prospective, controlled study in military recruits (in development).We present: 1. Literature-Based Comparisons (for diagnosing hr-CVCs): Two recent studies using traditional methods to identify hr-CVCs in >3,000 young athletes are compared with our s-MRI-based study of 5,169 adolescents. 2. Critical Review of Previous Results: The reported incidence of SCD in athletes is presently based on retrospective, observational, and incomplete studies. H&P’s screening value seems minimal for structural heart disease, versus echocardiography (which improves diagnosis for high-risk cardiomyopathies) and s-MRI (which also identifies high-risk coronary artery anomalies). Electrocardiography is valuable in screening for potentially high-risk electrophysiological anomalies. 3. Proposed Project: We propose a prospective, controlled study (2 comparable large cohorts: one historical, one prospective) to compare: (1) diagnostic accuracy and resulting mortality-prevention performance of traditional screening methods versus questionnaire/electrocardiography/s-MRI, during 2-month periods of intense, structured exercise (in military recruits, in advanced state of preparation); (2) global costs and cost/efficiency between these two methods. This study should contribute significantly toward a comprehensive understanding of the incidence and causes of exercise-related mortality (including establishing a definition of hr-CVCs) while aiming to reduce mortality.

Primary care physicians often must decide whether statin therapy would be appropriate (in addition to lifestyle modification) for managing asymptomatic individuals with borderline or intermediate risk for developing atherosclerotic cardiovascular disease (ASCVD), as assessed on the basis of traditional risk factors. In appropriate subjects, a simple, noninvasive measurement of coronary artery calcium can help clarify risk. Coronary atherosclerosis is a chronic inflammatory disease, with atherosclerotic plaque formation involving intimal inflammation and repeated cycles of erosion and fibrosis, healing and calcification. Atherosclerotic plaque formation represents the prognostic link between risk factors and future clinical events. The presence of coronary artery calcification is almost exclusively an indication of coronary artery disease, except in certain metabolic conditions. Coronary artery calcification can be detected and quantified in a matter of seconds by noncontrast electrocardiogram‐gated low‐dose X‐ray computed tomography (coronary artery calcium scoring [CACS]). Since the publication of the seminal work by Dr. Arthur Agatston in 1990, a wealth of CACS‐based prognostic data has been reported. In addition, recent guidelines from various professional societies conclude that CACS may be considered as a tool for reclassifying risk for atherosclerotic cardiovascular disease in patients otherwise assessed to have intermediate risk, so as to more accurately inform decisions about possible statin therapy in addition to lifestyle modification as primary preventive therapy. In this review, we provide an overview of CACS, from acquisition to interpretation, and summarize the scientific evidence for and the appropriate use of CACS as put forth in current clinical guidelines.

Cardiac magnetic resonance enables comprehensive cardiac evaluation; however, intense time and labor requirements for data acquisition and processing have discouraged many clinicians from using it. We have developed an alternative image-processing algorithm that requires minimal user interaction: an ultrafast algorithm that computes left ventricular ejection fraction (LVEF) by using temporal intensity variation in cine balanced steady-state free precession (bSSFP) short-axis images, with or without contrast medium. We evaluated the algorithm's performance against an expert observer's analysis for segmenting the LV cavity in 65 study participants (LVEF range, 12%-70%). In 12 instances, contrast medium was administered before cine imaging. Bland-Altman analysis revealed quantitative effects of LV basal, midcavity, and apical morphologic variation on the algorithm's accuracy. Total computation time for the LV stack was <2.5 seconds. The algorithm accurately delineated endocardial boundaries in 1,132 of 1,216 slices (93%). When contours in the extreme basal and apical slices were not adequate, they were replaced with manually drawn contours. The Bland-Altman mean differences were <1.2 mL (0.8%) for end-diastolic volume, <5 mL (6%) for end-systolic volume, and <3% for LVEF. Standard deviation of the difference was ≤4.1% of LV volume for all sections except the midcavity in end-systole (8.3% of end-systolic volume). We conclude that temporal intensity variation-based ultrafast LVEF computation is clinically accurate across a range of LV shapes and wall motions and is suitable for postcontrast cine SSFP imaging. Our algorithm enables real-time processing of cine bSSFP images on a commercial scanner console within 3 seconds in an unobtrusive automated process.

Unroofed coronary sinus defects are rare anomalies that result from abnormal embryologic development, leading to a partial or complete absence of the wall between the coronary sinus and the left atrium. This accounts for less than 1% of all atrial septal defects (ASD). Delayed diagnosis may lead to

Purpose To develop a dual-echo phase-contrast (DEPC) MRI approach with which each echo is acquired by using a different velocity sensitivity within one repetition time (TR) and demonstrate the feasibility of this approach to measure transmitral blood flow (E) and myocardial tissue (E m) velocities. Materials and Methods The flow across tubes of known diameter was measured by using the proposed DEPC method and compared with flowmeter measurements and theoretic predictions. Then, with both the DEPC MRI sequence and the conventional single-echo phase-contrast (SEPC) MRI sequence, E, E m, and E/E m were measured in six healthy volunteers (mean age, 49 years ± 13 [standard deviation]) and eight patients (mean age, 54 years ± 15) being evaluated for cardiac disease. Differences between the DEPC and conventional SEPC MRI methods were assessed by percent error, Pearson correlation, and Bland-Altman analyses. Results Velocities measured in vitro and in vivo by using the SEPC and DEPC MRI approaches were well correlated (r 2 > 0.97), with negligible bias (<0.5 cm/sec) and comparable velocity-to-noise ratios. Imaging times were approximately 19% shorter with the DEPC method (TR, 5.7 msec) than with the SEPC method (TR, 2.8 msec ± 4.2) (P < .05). Conclusion The proposed DEPC method was sensitive to two velocity regimes within a single TR, resulting in a shorter imaging time compared with the imaging time in conventional SEPC MRI. Preliminary human study results suggest the feasibility of using this approach to estimate E/E m.Supplemental material is available for this article.© RSNA, 2020.

In a previous cross-sectional screening study of 5,169 middle and high school students (mean age, 13.1 ± 1.78 yr) in which we estimated the prevalence of high-risk cardiovascular conditions associated with sudden cardiac death, we incidentally detected by cardiac magnetic resonance (CMR) 959 cases (18.6%) of left ventricular noncompaction (LVNC) that met the Petersen diagnostic criterion (noncompaction:compaction ratio >2.3). Short-axis CMR images were available for 511 of these cases (the Short-Axis Study Set). To determine how many of those cases were truly abnormal, we analyzed the short-axis images in terms of LV structural and functional variables and applied 3 published diagnostic criteria besides the Petersen criterion to our findings. The estimated prevalences were 17.5% based on trabeculated LV mass (Jacquier criterion), 7.4% based on trabeculated LV volume (Choi criterion), and 1.3% based on trabeculated LV mass and distribution (Grothoff criterion). Absent longitudinal clinical outcomes data or accepted diagnostic standards, our analysis of the screening data from the Short-Axis Study Set did not definitively differentiate normal from pathologic cases. However, it does suggest that many of the cases might be normal anatomic variants. It also suggests that cases marked by pathologically excessive LV trabeculation, even if asymptomatic, might involve unsustainable physiologic disadvantages that increase the risk of LV dysfunction, pathologic remodeling, arrhythmias, or mural thrombi. These disadvantages may escape detection, particularly in children developing from prepubescence through adolescence. Longitudinal follow-up of suspected LVNC cases to ascertain their natural history and clinical outcome is warranted.

We read with interest the recent article by Williams et al1 and the accompanying editorial comment by Maron et al2 on the current status of the discussion on preventing sudden cardiac death (SCD) in young athletes. SCD in the young is devastating to all involved— families, healthcare providers, the community—and attracts considerable attention from the public and media.3 As our esteemed teacher (Dr. Barry Maron) stated in foundational 2007 guidelines, preventing SCD in athletes is a basic constitutional duty in sports cardiology.4 Nonetheless, >10 years later, reports of SCD episodes in athletes continue unabated. These are often promptly followed by announcements of forthcoming autopsy, which offends the sensitivity of many families and exposes a failure to recognize conditions that we regularly detect in daily clinical experience. These observations belie the view put forth by Maron et al2 that there is no reason to adopt electrocardiography or any other diagnostic method in place of the medical history and physical examination (H&P) initially recommended by the American Heart Association/American College of Cardiology for detecting cardiovascular diseases in the young. This assumes that we should be satisfied with the supposed preventive achievements of H&P, but this notion has never been proven valid for diagnosing highrisk cardiovascular conditions (hrCVCs) or saving lives—not in adequately sized populations, and not in welldesigned, controlled studies. Athletes and military personnel are at essentially the same risk for SCD during strenuous activities, yet only trivial advances have been made toward reducing the regular occurrence of SCD in these populations. This is particularly disappointing, because most cardiologists agree with Maron et al’s claim that SCD during strenuous exertion is primarily caused by preexisting structural heart disease,4 such as cardiomyopathy and coronary artery anomalies (CAAs)—conditions that today’s technological advances have rendered clinically and confidently identifiable. Even so, the true incidence and causes of SCD are unclear: In athletes, estimates vary from almost 1:1 million to 1:23 000 annually, and as high as 1:3000 in some subpopulations (basketball players).5 As for the US military, Eckart et al’s6 2004 study of 6.3 million candidates suggests an annualized shortterm medical mortality rate of ≈13:100 000 recruits/year during 2month boot camp training; interestingly, 87% of fatalities were exertionrelated, and 33% of cardiac causes were CAArelated. Our aim in this Viewpoints article is to reopen the discussion on what is easily within our capacity to do

Transcatheter aortic valve replacement (TAVR) initially emerged as an alternative option to surgical aortic valve replacement (SAVR) for patients with severe aortic stenosis who were considered either inoperable or high-risk for surgery. However, since its advent the role of TAVR has been continuously evolving on the basis of clinical trials which showed that TAVR is non-inferior to SAVR in patients with moderate as well as low-risk for surgery. Because of recent technological advances, multidetector computer tomography (MDCT) is inherently suitable for the pre-procedural assessment of patients being considered for TAVR within a very short imaging time, MDCT can measure the diameter of the aortic annulus, provide detailed information regarding the status of the entire thoracoabdominal aorta, and assess the caliber of the peripheral vasculature used for transcatheter heart valve delivery. This information helps interventionists make optimal pre-procedural decisions and avoid complications. To familiarize non-imaging specialists with the role of MDCT in TAVR, we provide a concise overview of our approach to using this modality for the pre-procedural assessment of TAVR candidates.

The poor retention and survival of cells after transplantation to solid tissue represent a major obstacle for the effectiveness of stem cell-based therapies. The ability to track stem cells in vivo can lead to a better understanding of the biodistribution of transplanted cells, in addition to improving the analysis of stem cell therapies’ outcomes. Here, we described the use of a carbon nanotube-based contrast agent (CA) for X-ray computed tomography (CT) imaging as an intracellular CA to label bone marrow-derived mesenchymal stem cells (MSCs). Porcine MSCs were labeled without observed cytotoxicity. The CA consists of a hybrid material containing ultra-short single-walled carbon nanotubes (20–80 nm in length, US-tubes) and Bi(III) oxo-salicylate clusters which contain four Bi 3+ ions per cluster (Bi 4 C). The CA is thus abbreviated as Bi 4 C@US-tubes.

OBJECTIVE:We determined the effect of antegrade stent delivery in the descending thoracic aorta on short- and mid-term clinical and imaging outcomes for patients who underwent repair of acute DeBakey type I aortic dissection. METHODS:Outcomes were evaluated for 178 patients who underwent acute type I aortic dissection between 2005 and 2016 (standard repair, n = 115 [64.6%]; antegrade stent delivery, n = 63 [35.4%]). Propensity score match and multivariable analyses were performed to assess outcomes. RESULTS:The stent and standard repair groups had similar rates of operative mortality (30-day or in-hospital) (12.7% vs 17.4%, P = .41), persistent stroke (6.3% vs 5.3%, P = .75), and persistent paraplegia/paraparesis (1.6% vs 0.9%, P = 1.0). Propensity score match analysis indicated that the operative mortality rate was higher in the standard repair group (P = .059), which the multivariable analysis confirmed. The persistent stroke rate was nonsignificantly higher in the stent group (P = .66). Persistent paraplegia/paraparesis rates were similar in both groups (P = 1.0), and the overall rates of spinal cord ischemia were nonsignificantly higher in the stent group (P = .18). During follow-up (mean duration, 4.6 ± 3.6 y), computed tomography showed that stented patients more often had remodeling of the descending thoracic aorta (P = .0002) and somewhat more often had remodeling of the thoracoabdominal aorta (P = .13). Stented patients also had fewer subsequent procedures (P = .25). The 3- and 5-year survivals were 73.3% ± 6.9% and 49.9% ± 7.6% in the matched stented group and 66.3% ± 9.4% and 41.6% ± 7.7% in the matched standard group, respectively (P = .015 for overall survival). CONCLUSIONS:In the short term, antegrade stent delivery was associated with less operative mortality. In the mid-term, promising remodeling of the false lumen was seen in stented patients, as were (nonsignificantly) lower rates of subsequent procedures in the thoracoabdominal aorta. Mid-term survival was also greater in the stented patients.

BACKGROUND:Breath-hold cine MR is the method of choice for evaluating left ventricular (LV) systolic function; however, the evaluation of diastolic function remains in the domain of high frame rate echocardiography. Thus, a cine MR technique for simultaneously evaluating LV systolic and diastolic function would be clinically valuable. PURPOSE:To test the feasibility of extracting indices that characterize LV diastolic function from high frame rate cine MR. STUDY TYPE:Single center, prospective. POPULATION:Asymptomatic volunteers (N = 24; age 45.8 ± 12.3 years). FIELD STRENGTH/SEQUENCE:High frame rate (70 fps) cine MR and phase-contrast MR during free breathing were acquired at 1.5T. ASSESSMENT:The following MR-based LV filling metrics were extracted from LV volume changes during the cardiac cycle: 1) the volume-rate ratio, REFP /RLFP (ratio of the peak LV filling rate during the early filling period [EFP] to that during the late filling period [LFP]); and 2) the volume ratio, VEFP /VLFP (the ratio of cumulative LV volume change between the EFP and LFP). These metrics were then compared with traditional transmitral blood flow-based MR and echocardiographic indices. The effect of temporal resolution on these metrics was also evaluated. STATISTICAL TESTS:Bland-Altman and linear regression analyses were used to evaluate the performance of the proposed metrics against traditional indices of diastolic function. RESULTS:The REFP /RLFP and VEFP /VLFP correlated well with E/AQ-flow (r 2 = 0.66 and 0.54, respectively) and E/Aecho (r 2 = 0.58 and 0.49, respectively). Systolic indices remained robust (<3% error) for frame rates ≥20 fps. Although the proposed VEFP /VLFP was robust (<5% error) up to 25 fps, the proposed volume-rate diastolic function metrics were less reliable (>8% error) for frame rates below 35 fps. DATA CONCLUSION:In asymptomatic volunteers, cardiac cine MR images acquired at frame rates >35 fps can be used to extract LV diastolic function indices from the temporal changes in LV volume. LEVEL OF EVIDENCE:1 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019;50:1571-1582.

Dextro-transposition of the great arteries (D-TGA) is one of the most common cyanotic heart lesions. The arterial switch operation (ASO) is the preferred surgical palliation for D-TGA. One of the primary concerns following the ASO is complications arising from the coronary artery transfer. There is a need for myocardial perfusion assessment within ASO patients. There is no report on the utility of regadenoson as a stress agent in children following ASO. Our objective was to observe the safety and feasibility of regadenoson as a pharmacologic stressor for perfusion cardiac MR in a pilot cohort of pediatric and young-adult patients who have undergone ASO. We reviewed our initial experience with regadenoson stress cardiac MR in 36 pediatric and young-adult patients 15.1 ± 4.5 years (range 0.2–22 years) with history of ASO. The weight was 61.6 ± 21.5 kg (range 3.8–93 kg). All patients underwent cardiac MR because of concern for ischemia. Subjects’ heart rate and blood pressure were monitored and pharmacologic stress was induced by injection of regadenoson. We evaluated their hemodynamic response and adverse effects using changes in vital signs and onset of symptoms. A pediatric cardiologist and radiologist qualitatively assessed myocardial perfusion and viability images. All stress cardiac MR examinations were completed without adverse events. Resting heart rate was 72 ± 13 beats per minute (bpm) and rose to peak of 120 ± 17 bpm (95 ± 50% increase, p < 0.005) with regadenoson. Image quality was considered good or diagnostic in all cases. A total of 11/36 (31%) patients had a perfusion defect on the stress FPP images. 14 of the 36 patients (39%) underwent cardiac catheterization within 6 months of the CMR and the findings showed excellent agreement. Regadenoson may be a useful coronary hyperemia agent to utilize for pediatric patients following arterial switch procedure when there is concern for ischemia. The ability to administer as a single bolus with one IV makes it advantageous in pediatrics. In a limited number of cases, regadenoson stress perfusion showed excellent agreement with cardiac catheterization.

Improving screening of candidates for participation in sports requires accurate methods of identifying high-risk cardiovascular conditions (hr-CVCs) that predispose young people to sudden cardiac death (SCD). Most sports-related SCDs are potentially preventable if recognized before an adverse

A 70-year-old woman, told that her pacemaker lead was lying over her aorta, presented for a second opinion. Four years earlier, after a syncopal spell, she had undergone dual-chamber pacemaker placement. Transthoracic echocardiograms revealed that her ventricular pacemaker lead was in her left ventricle (LV). To determine the course of the ventricular lead, transesophageal echocardiography and computed tomographic angiography of the chest were performed (Fig. 1). The lead originated in the subclavian vein but then entered the left common carotid artery, approximately 3.3 cm from its ostium. The lead then coursed through the transverse aortic arch, proximal ascending aorta, and aortic valve, terminating in the distal lateral wall of the LV. The right atrial lead followed the usual venous course into the right atrium. After hearing the risks and benefits of surgically removing the lead from the left common carotid artery, the patient chose lifelong anticoagulation for stroke prophylaxis.Malposition of a ventricular lead in the LV occurs infrequently,1,2 and its prevalence has not been reported. Although the lead in our patient traversed the aortic valve, inadvertent crossing of the interatrial septum has been reported more often.3 Potential complications of lead malposition in the LV include systemic thromboembolism, perforation of the aortic or mitral valve leaflets, arterial thrombosis, and loss of capture.4 If malposition is diagnosed immediately after pacemaker implantation, lead removal may be considered.5 Otherwise, the lead should be left in place and lifelong anticoagulation prescribed to reduce the risk of systemic embolization.4

Breath-hold (BH) requirement remains the limiting factor on the spatio-temporal resolution and coverage of the cine balanced steady-state free precession (bSSFP) cardiovascular magnetic resonance (CMR) imaging. In this prospective two-center clinical trial, we validated the performance of a respiratory triggered (RT) bSSFP cine sequence for evaluation of biventricular function.

Rationale: Hypertrophic cardiomyopathy (HCM) is a genetic paradigm of cardiac hypertrophy. Cardiac hypertrophy and interstitial fibrosis are important risk factors for sudden death and morbidity in HCM. Oxidative stress is implicated in the pathogenesis of cardiac hypertrophy and fibrosis. Treatment with antioxidant N-acetylcysteine (NAC) reverses cardiac hypertrophy and fibrosis in animal models of HCM. Objective: To determine effect sizes of NAC on indices of cardiac hypertrophy and fibrosis in patients with established HCM. Methods and Results: HALT-HCM (Hypertrophy Regression With N-Acetylcysteine in Hypertrophic Cardiomyopathy) is a double-blind, randomized, sex-matched, placebo-controlled single-center pilot study in patients with HCM. Patients with HCM, who had a left ventricular wall thickness of >= 15 mm, were randomized either to a placebo or to NAC (1: 2 ratio, respectively). NAC was titrated <= 2.4 g per day. Clinical evaluation, blood chemistry, and 6-minute walk test were performed every 3 months, and electrocardiography, echocardiography, and cardiac magnetic resonance imaging, the latter whenever not contraindicated, before and after 12 months of treatment. Eighty-five of 232 screened patients met the eligibility criteria, 42 agreed to participate; 29 were randomized to NAC and 13 to placebo groups. Demographic, echocardiographic, and cardiac magnetic resonance imaging phenotypes at the baseline between the 2 groups were similar. WSE in 38 patients identified a spectrum of 42 pathogenic variants in genes implicated in HCM in 26 participants. Twenty-four patients in the NAC group and 11 in the placebo group completed the study. Six severe adverse events occurred in the NAC group but were considered unrelated to NAC. The effect sizes of NAC on the clinical phenotype, echocardiographic, and cardiac magnetic resonance imaging indices of cardiac hypertrophy, function, and extent of late gadolinium enhancement-a surrogate for fibrosis-were small. Conclusions: Treatment with NAC for 12 months had small effect sizes on indices of cardiac hypertrophy or fibrosis. The small sample size of the HALT-HCM study hinders from making firm conclusions about efficacy of NAC in HCM.

Rationale: Hypertrophic cardiomyopathy (HCM) is a genetic paradigm of cardiac hypertrophy. Cardiac hypertrophy and interstitial fibrosis are important risk factors for sudden death and morbidity in HCM. Oxidative stress is implicated in the pathogenesis of cardiac hypertrophy and fibrosis. Treatment with antioxidant N-acetylcysteine (NAC) reverses cardiac hypertrophy and fibrosis in animal models of HCM. Objective: To determine effect sizes of NAC on indices of cardiac hypertrophy and fibrosis in patients with established HCM. Methods and Results: HALT-HCM (Hypertrophy Regression With N-Acetylcysteine in Hypertrophic Cardiomyopathy) is a double-blind, randomized, sex-matched, placebo-controlled single-center pilot study in patients with HCM. Patients with HCM, who had a left ventricular wall thickness of ≥15 mm, were randomized either to a placebo or to NAC (1:2 ratio, respectively). NAC was titrated ≤2.4 g per day. Clinical evaluation, blood chemistry, and 6-minute walk test were performed every 3 months, and electrocardiography, echocardiography, and cardiac magnetic resonance imaging, the latter whenever not contraindicated, before and after 12 months of treatment. Eighty-five of 232 screened patients met the eligibility criteria, 42 agreed to participate; 29 were randomized to NAC and 13 to placebo groups. Demographic, echocardiographic, and cardiac magnetic resonance imaging phenotypes at the baseline between the 2 groups were similar. WSE in 38 patients identified a spectrum of 42 pathogenic variants in genes implicated in HCM in 26 participants. Twenty-four patients in the NAC group and 11 in the placebo group completed the study. Six severe adverse events occurred in the NAC group but were considered unrelated to NAC. The effect sizes of NAC on the clinical phenotype, echocardiographic, and cardiac magnetic resonance imaging indices of cardiac hypertrophy, function, and extent of late gadolinium enhancement—a surrogate for fibrosis—were small. Conclusions: Treatment with NAC for 12 months had small effect sizes on indices of cardiac hypertrophy or fibrosis. The small sample size of the HALT-HCM study hinders from making firm conclusions about efficacy of NAC in HCM. Clinical Trial Registration: URL: http://www.clinicaltrials.gov . Unique identifier: NCT01537926.

Improving preparticipation screening of candidates for sports necessitates establishing the prevalence of high-risk cardiovascular conditions (hr-CVC) that predispose young people to sudden cardiac death (SCD). Our accurate, novel protocol chiefly involved the use of cardiac magnetic resonance (CMR) to estimate this prevalence. Middle and high school students from a general United States population were screened by means of questionnaires, resting electrocardiograms, and CMR to determine the prevalence of 3 types of hr-CVC: electrocardiographic abnormalities, cardiomyopathies, and anomalous coronary artery origin from the opposite sinus with intramural coronary course (ACAOS-IM). We examined the range of normal left ventricular size and function in the main study cohort (schoolchildren 11-14 yr old). We defined diagnostic criteria for hr-CVC and compared the cardiac measurements of these younger participants with those of older children whom we examined (age, 15-18 yr). From 5,169 completed diagnostic studies (mean participant age, 13.06 ± 1.78 yr), CMR results revealed 76 previously undiagnosed cases of hr-CVC (1.47% of the total cohort): 11 of dilated cardiomyopathy (14.5%), 3 of nonobstructive hypertrophic cardiomyopathy (3.9%), 23 ACAOS-IM cases (30.3%; 6 left-ACAOS and 17 right-ACAOS), 4 Wolff-Parkinson-White patterns (5.3%), 34 prolonged QT intervals (44.7%), and 1 Brugada pattern (1.3%). Cardiomyopathies were significantly more prevalent in the older children. Of note, we identified 959 cases (18.5%) of left ventricular noncompaction. If our estimate is accurate, only 1.47% of school-age sports participants will need focused secondary evaluations; the rest can probably be reassured about their cardiac health after one 30-minute screening study.