A 60-year-old man came to emergency with sudden-onset cough with yellow sputum production and dyspnea.He is taking amlodipine for hypeension. Chest X-ray shows a left upper lobe alveolar infiltrate and investigations shows Hb of 6g/dL, BUN of 60 mg/dL, Creatinine of 2.8 mg/dL, Calcium of 12.3 mg/dL, total protein of 9 g/dL and albumin of 4.2 g/dL.On Echocardiogram dilated hea is seen and peripheral neuropathy is also present. Most common cause of death in the above described disease is: