Middle-aged Man with Syncope

ECG CHALLENGE QuestionA man in his late 40s presented with a history of syncope and fall.He was an ex-smoker.He denied any exertional symptoms and was otherwise in good health.The cardiovascular examination was within normal limits.A 12-lead electrocardiogram (ECG) done at presentation is shown in Figure 1.A noncontrast computed tomography (CT) scan of the head did not show any abnormality.The initial echocardiogram done prior to referral was reported to have concentric left ventricular hypertrophy and normal ventricular function.What is the possible diagnosis?