A 69 year old male presents with an episode of slurring of speech which lasted for 12 hours and then resolved.He is heavy smoker having smoked 60 cigarettes per day for 40 years. He had a single episode of haemoptysis 4 weeks previously and has underlying lung cancer with brain metastases and is referred for an urgent CT chest. An ECG was performed which showed new AF. All blood tests including cardiac biomarkers were normal. Chest CT is shown. Which of the following is most probable diagnosis?