The aim of the report of this highly challenging case is to depict how sudden unexplained deaths can sometimes be associated to many atypical and complex findings, albeit of unknown significance. At the autopsy, the only relevant macroscopic finding was the myocardial bridging of left anterior descending coronary artery in the context of a normal heart. In general terms, MB is a congenital coronary anomaly that usually affects the middle tract of left anterior descending coronary artery and is often found for the first time only at autopsy . According to many authors, when it is particularly thick , it may cause myocardial ischemia, but it is controversial if it can be considered a possible cause of SCD . Myocardial bridging has been also reported in men with no family history of sudden cardiac death in which the first clinical manifestations of BrS were acute chest pain and syncope .

A causal relationship between this coronary anomaly and BrS has never been proved, but Riezebos et al. hypothesized that “interaction between the provoked ischemia and the specific repolarization abnormalities that are caused by the Brugada syndrome could provide an electrophysiological substrate that may increase individual susceptibility to life-threatening ventricular tachyarrhythmias” . Microscopic examination of the atria and ventricles found some interesting and complex features. Starting from the left ventricle, fibrosis and disarray in the myocardial area above the MB were described. These features have already been associated to MB in young cases of SD . In particular, considering the young age, the presence of fibrosis and disarray without ventricular hypertrophy in regions far from the septum is compatible with an early phenotype of HCM . It should be considered that the abnormal weight of the heart is also suggestive of HCM. In our case, there also was a sign suggestive of arrhythmogenic cardiomyopathy : the fatty infiltration of the right ventricle.

However, this feature was only found in the antero-lateral region of the right ventricle, a localization that is typical of physiological conditions . Moreover, the fatty infiltration was clearly separated by the myocardium, and there were no signs of necrosis/atrophy of the myocytes , no fibrous or fibro-fatty infiltration of the myocardium and no inflammatory infiltrates . Finally, NGS found no variant pathogenic for ACM. All these data suggest a physiological condition. However, this finding is atypical, because fatty infiltration of the myocardium generally affects elderly or obese patients, and our case was young and non-obese . Hence, since the absence of signs of cardiomyopathy, a clear pathogenic significance cannot be given to the findings. However, it should be considered that some authors reported that fatty infiltration could cause arrhythmias because it represents a structural barrier to the heart electrical impulse and causes oxidative stress. In particular,previous cases of sudden death in patients with fat of the free wall of the right ventricle have been reported . Another interesting microscopic feature was the fibrosis of the sino-atrial node area.

In sudden death cases, it is important that an expert pathologist carefully examines the conduction system, as recommended, among others, by Ottaviani and Buja and by The Royal College of Pathologists . Indeed, this analysis can help to find the cause of the death but is complicated, for example, by the interindividual anatomical variability. The feature we found in our case is considered physiological since fibrosis has been described as a “modulator of structural and functional integrity” of sino-atrial node.In our case, the found amount of fibrosis in the sino-atrial node area is relatively unusual for the young age of the victim . However, despite the crucial function of this pacemaker and the presence of important structures, such as Nav1.5 channels-in the periphery of its area, according to current evidence, no pathological significance of this feature can be assessed.In conclusion, the autopsy revealed a long and thick MB located in a very proximal tract of the coronary artery and surrounded by signs suggestive of HCM/MB-caused ischemic damage. Moreover, fatty infiltration of the right ventricle and significant fibrosis of the sino-atrial node area were found. These features are relatively common in the general population but are atypical in a young and healthy patient.In our case, the victim was reportedly a habitual cannabis consumer, and the friend who witnessed his death told the police that he had smoked cannabis few tens of minutes before his death. Toxicologic testing was positive for cannabis use. However, THC concentration in peripheral blood was low. Marijuana use has been associated with a wide spectrum of cardiac adverse effects and, in particular, with arrhythmias .