Cardiac Screening - Soccer

Abstract

HISTORY: 18 year old male collegiate soccer player presented for routine physical for varsity soccer team. Unremarkable past medical history aside from an adenectomy as a child. Negative sickle cell disease screening and up to date on vaccinations. Screening EKG notable for a prolonged QT/QTc 520/510ms. He denied any cardiac symptoms, but noted a syncopal event at age 16, when he went from sitting to standing, associated with blurry vision and dizziness. At that time, he had quick return of consciousness and did not seek medical attention. Denied use use of any performance-enhancing drugs PHYSICAL EXAMINATION: General: athletic young man HEENT: midline trachea, no thyroid enlargement Respiratory: lungs clear to auscultation and percussion Cardiovascular: sinus bradycardia, no murmurs Abdomen: non-tender without organomegaly Extremities: no edema DIFFERENTIAL DIAGNOSIS: Congenital LQTS; Acquired LQTS; Bradyarrhythmia (AV block) TEST AND RESULTS: BMP and TSH normal; Repeat EKG significant for bradycardia, uncorrected QT 520ms, broad-based T wave. Echocardiogram with ejection fraction 62%, structurally normal. Wore a Zio patch: range of 33bpm-176bpm, average 61bpm. Predominantly sinus. Underwent stress testing, reached 81.2% predicted MHR, BP 178/75, no chest discomfort, normal ST segment response to stress. Referred to Genetic Counsellor for Diagnostic Testing. The pathogenic variant, c.1552CT (p.Arg518*), was identified in KCNQ1 (AD/AR arrhythmia conditions), as well as variants of uncertain significance in MYH6 and RBM20. FINAL WORKING DIAGNOSIS: Congenital long QT syndrome (LQTS) due to heterozygous mutation at KCNQ1, Exon 12, c.1552C >T (p.Arg518*). This pathogenic mutation causes a premature translational stop signal at codon 518 of KCNQ1 gene, this is known to cause LQTS. Heterozygous carriers with typically mild clinical manifestions. TREATMENT AND OUTCOMES: The athlete was started on nadolol 40mg tablet once daily, then uptitrated to 80mg shortly thereafter. A repeat EKG showed sinus bradycardia and a shorter QT 480ms. Repeat stress testing notable for a blunted heart rate response (as expected on a beta-blocker), QT of 380ms with no QT prolongation during maximal exercise. The athlete’s family purchased a defibrillator for home use, and he has been cleared to return to varsity athletics.