A 54 year old lady presents with dyspnoea and marked peripheral oedema. She has no significant past medical history. Her blood pressure is 108/68 mmHg and there are no cardiac murmurs on examination. NT-pro-BNP level returns as 453 pmol/L (range 47-236 pmol/L) and subsequent echocardiography demonstrates an ejection fraction of 55%.
Based on the likely diagnosis, what is the most appropriate treatment option?