Improving patient selection for complex cardiac implantable electronic devices

: Pathophysiological insights, biomarkers and cost effectiveness

Abstract

Cardiac resynchronisation Therapy Devices (CRT) and Implantable Cardioverter Defibrillators (ICDs) are routinely implanted in heart failure patients and patients at risk of ventricular arrhythmias (VA). Not all patients with CRT experience an improvement with symptoms and not all patients with an ICD receive an appropriate shock or therapy. Improved patient selection for these devices would be beneficial and is the focus of this thesis with my investigations focusing on the underlying pathophysiological mechanisms of dyssynchronous heart failure, potential novel imaging biomarkers to predict outcomes from complex cardiac devices and also an analysis of the cost-effectiveness implications of improved patient selection.
Recent research has suggested a role of improved coronary flow in patients who respond to CRT and also an improved haemodynamic response to left ventricular endocardial pacing. We performed a prospective clinical study to assess whether left ventricular endocardial pacing improved coronary flow and a further sub-study to investigate the relationship between coronary flow and acute contractility.
Our understanding of the role of myocardial fibrosis and scar in the pathogenesis of VA is evolving and it is now possible to assess both of these entities using cardiac magnetic resonance imaging (CMR). We performed a prospective study to determine whether CMR identification of fibrosis and scar could be used to predict VA in an ICD population specifically focusing of measures of myocardial fibrosis in patients with non-ischemic cardiomyopathy and measure of myocardial scar and peri-infarct heterogeneity (grayzone) in patients with ischemic cardiomyopathy. This study demonstrated for the first time that T1 mapping (a marker of fibrosis) was a specific markers of risk in the non-ischemic group whereas grayzone predicted risk in the ischemic group.
Finally, I used published data to demonstrate the cost-effectiveness of a risk stratification tool which determines whether CRT defibrillator patients should be offered a further CRT defibrillator or a CRT pacemaker at the time of generator change.

Date of Award	2019
Original language	English
Awarding Institution	King's College London
Supervisor	Reza Razavi (Supervisor)