Mechanistic Insights From Temporary Pacing in HFpEF

In this research study, the investigators will perform a one-off temporary pacing procedure in the catheter lab at St Thomas' Hospital in patients with heart failure with preserved ejection fraction (HFpEF). During the short procedure, the investigators will pace the heart at different heart rates and from different parts of the heart. The investigators will measure the change in pressure inside the heart in response to each pacing site/mode and rate. Altogether, the investigators aim to find out how different pacing modes and heart rates impact how well the heart fills and pumps in HFpEF. The study will provide valuable information about the underlying mechanisms of pacing in HFpEF, which could significantly influence the future direction of HFpEF management. Specifically, it will help the investigators to understand what types of pacemaker and pacing site or pacing mode may be chosen in HFpEF patients requiring pacing, which accounts for around 20% of all HFpEF patients.