Abstract Background Myocarditis is a known cause of sudden cardiac death of the athlete. The impact of direct chest trauma in at-risk sports or activities in patients with a history of myocarditis has never been demonstrated or studied. We report herein two cases of life-threatening ventricular arrhythmia secondary to non-penetrating blunt chest trauma while playing contact sports. Case summary The first patient, a 26-year-old man described a brief loss of consciousness after having received blunt impact to the chest (typical intensity) while playing a rugby match. The loss of consciousness was total and proceeded by rapid and regular palpitations. He had a history of viral myocarditis 10 years prior with a fibrotic sequalae in the inferolateral wall on cardiac magnetic resonance imaging (left ventricular ejection fraction 71%). Right apical ventricular pacing induced a sustained monomorphic ventricular tachycardia reproducing the patient’s symptoms. A subcutaneous implantable cardioverter-defibrillator was implanted. The second patient is a 22-year-old professional rugby player with no known notable history. During a match, a direct blow to the chest wall was followed by a cardiac arrest. A ventricular fibrillation was cardioverted to pulseless electrical activity. Patient died despite cardiopulmonary resuscitation. An autopsy identified a myocardial sequela of fibrosis with no acute inflammatory remodelling compatible with a previous myocarditis. Discussion Myocarditis may increase the risk of life-threatening ventricular arrhythmias caused by blunt impact to the chest, particularly in contact sports. Screening and prevention measures should be considered to reduce this risk.