Cardiologists’ Knowledge, Attitudes and Application of Risk towards Implantable Cardioverter Defibrillators.

Patients with impaired left ventricular systolic function have an increased risk of sudden cardiac death. The implantable cardioverter defibrillator (ICD) is an effective therapy to treat life-threatening arrhythmias and randomized controlled trials have demonstrated statistically significant reductions in all-cause mortality in select patient groups. Despite this wealth of published data, the uptake of ICDs in high risk population remains low and the exact reasons not known. My study focuses on the evidence for ICD therapy from the landmark RCTs that have influenced the current guidelines. Most trials have only published relative risk reduction or hazard ratios. The first part of this thesis analyzes data to reveal absolute risk reduction, the number needed to treat and the findings standardized for length of follow-up. There is considerable variation in the magnitude of benefit between different heart failure aetiologies and other patient characteristics highlighting the difficulty in generalising the results. UK cardiologists’ knowledge of guidelines, estimates of 3-year mortality, management decisions, factors that influence decisions, influence of age, device cost, and overall attitudes to ICDs as a form of therapy was assessed with a questionnaire. There was lack of awareness of UK ICD guidelines amongst non-implanting cardiologists and even when guidelines were known they were often not applied, particularly in primary prevention setting. Most cardiologists are not aware of the magnitude of benefit an ICD offers and overestimate the effect in secondary prevention. In addition, there is also bias against elderly patients. The final part of my thesis focuses on exploring barriers to primary prevention ICD uptake. The aim was to see what action was taken when all the data required for making a referral or assessment was available. Our study suggests more than half of potentially eligible patients do not receive ICD therapy. A low referral rate, lack of screening programmes and age bias seem to be the stumbling blocks for primary prevention ICD in the UK.