Isolated non-ischemic left ventricular scar in athletes: scientific and clinical rationale behind the 2023 Recommendations of the Italian Sports Cardiology Guidelines (COCIS).

Isolated non-ischemic left ventricular scar (NLVS) refers to the presence of significant late gadolinium enhancement (LGE) with subepicardial/midmyocardial distribution detected through cardiac magnetic resonance (CMR) in the absence of other features of a specific disease and excluding the junctional spotty pattern that is not pathological. This nosographic entity is relatively recent, emerging with the widespread clinical use of CMR. The NLVS has recently been associated with cardiac arrest in sports. On the other hand, cohort where CMR was performed on apparently healthy volunteers revealed prevalence of around 5-10% in asymptomatic athletes, suggesting that in the majority of cases the condition has a benign course. Today, the most common clinical scenario involves the diagnosis of NLVS following a CMR performed for ventricular arrhythmias, often in the absence of family history, baseline ECG abnormalities, or ventricular dysfunction on echocardiography. However, the clinical presentation can range from relatively simple isolated premature ventricular beats to complex ventricular-arrhythmias and from limited LGE to extensive (ring-like) scars, sometimes associated with a positive genetic test. Although robust evidence for risk stratification is still lacking, it is reasonable to hypothesize a correlation between phenotype severity and arrhythmic risk, analogous to other cardiomyopathies. This article explores the pathophysiological hypotheses surrounding NLVS in athletes, the appropriate diagnostic work-up, strategies for risk stratification, and the recommendations for sports eligibility outlined in the recent 2023 Italian sports cardiology guidelines (COCIS).