 BASELINE CPET: CPET PhysiologistScientist Patients consenting for the study will perform symptom limited exercise using a ramped protocol on a cycle ergometer. This breath-by-breath system measures patients gas exchange, heart tracing 12-lead ECG and oxygen saturation continuously. The protocol will be as follows: A rest period for 3 minutes and then a further 3 minutes of unloaded pedaling followed by the ramped exercise of 10-20watt ramp depending on patients fitness for a period of 8-12 minutes approximately. 