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How to Work Up a Case of Sudden Cardiac Arrest in a Young Sportsman∗

Corresponding Author


CLINICAL MANIFESTATIONS OF R-ACAOS-IM
Most young athletes with R-ACAOS-IM perform normally during training and competing and rarely report pertinent symptoms, because a smaller territory is perfused by the right coronary artery than by the left coronary artery. Nonetheless, stenosis exists in every case studied by IVUS and ranges from 10% to 80% at diastole and 20% to 100% at systole in the cross-sectional area. The usual pre-event symptoms include chest pain (which is typical, related to exercise intensity; or atypical, unrelated to exertion), dyspnea, dizziness, and syncope (rare). Acute myocardial infarction also is rare (and never correlated with thrombus formation) (2,3). Sudden cardiac death (SCD) in R-ACAOS-IM (6-8) is exceptional and occurs mostly in males (probably 9 times more frequently than in females) and during exertion (>85% of cases) (6,9).  A right anterior oblique section at the level of the aortopulmonary sinus shows the proximal R-ACAOS-IM at its narrowest site (the Angelini-Cheong sign) in front of the anterior aortic commissure (arrow). The severity of stenosis can by estimated by computing the ratio between the long and short diameters. In this case, the ratio was 2.4 (moderate severity). Ao ¼ aorta; PA ¼ pulmonary artery; R-ACAOS-IM ¼ anomalous origin of a coronary artery from the opposite sinus of Valsalva (ACAOS) with intramural course involving the right coronary artery.
Revisiting Cardiac Arrest in Young Athletes identify ACAOS, as confirmed by this reviewer's large cardiac magnetic resonance (CMR) imaging-based screening study in students 11 to 18 years of age (10,11). Pre-event symptoms such as those mentioned above are rare before SCD or SCA or syncope but are potential manifestations of R-ACAOS-IM in an exceptionally severe phenotype or exercise conditions.
In cases of SCA, CTA is indicated (New York Heart Association functional class III symptoms) (3,5). The indication for CMR is less certain because its precision is less than ideal and because these individuals have Reports of the incidence of SCD in R-ACAOS-IM are limited (12). Especially notable are results from 6.3 million military recruits: SCD due to this condition was never reported, whereas 33% of the cases of SCD were due to L-ACAOS-IM in men (no women) (9). In another important study of young athletes (15 to 35 years of age), SCD was 4 times more frequent in L-ACAOS than in R-ACAOS, even though R-ACAOS-IM was found to occur approximately 3 times more frequently than L-ACAOS-IM in a CMR-based population study (10).
Pediatric cardiologists typically do not use IVUS in younger patients, partly due to unfamiliarity with such catheter procedures that are also less useful in children than in adults and because coronary acquired disease is not a factor at a younger age. The additional technical demands of selective catheterization relate to the tangential ostial anatomy that complicates tip catheter selective engagement and alignment. The introduction of dedicated catheters for R-ACAOS-IM cases easily resolved this difficulty (2). In adults, once IVUS has precisely identified the basic anatomical defect (location, length, severity of stenosis in systole and diastole, and ostial involvement), if the indication to treat the defect is well established, stent angioplasty can produce excellent immediate and late results and requires only a few additional minutes (2).
If surgery is performed, it is important to report operative findings, especially those confirming the presence of an IM course and its severity before performing unroofing (although stenosis is difficult to quantify in arrested hearts in the surgical suite (3).

CONCLUSIONS
In the context of preventing serious exercise-related clinical events, the fact that CMR may not be the best approach for quantifying the severity of a patient's R-ACAOS-IM does not exclude it as an excellent technique for screening populations at increased risk, such as athletes. Routine screening CMR has proven reliable for identifying ACAOS-IM without the need for intravenous lines, contrast medium, or ionizing radiation (10). Considering that 0.4% of the general population is born with some form of ACAOS-IM, a potentially high-risk condition that history and physical examination cannot identify, undergoing a CMR-dedicated unit with a competent interpreting team could identify up to 99% of such structural heart conditions and potentially prevent catastrophic surprises (10,11). Given a US population of 330 million, 0.4% represents 1.3 million carriers of ACAOS-IM, a substantial group and not only of concern during their sports years.
In sum, preventing SCD by screening is better than hoping to treat it effectively on the athletic field, where unheralded catastrophes may occur (12).

AUTHOR DISCLOSURES
The author has reported that he has no relationships relevant to the contents of this paper to disclose.