LV Endocardial Cardiac Resynchronisation Therapy

Cardiac resynchronisation therapy (CRT) is an established treatment for severe systolic heart failure with well documented benefits in symptom improvement and reduction of morbidity and mortality. However, upto 30% of patients do not respond to treatment despite fulfilling the recommended indications. Lack of clinical response may be the result of imperfect left ventricular lead placement in the veins around the heart with conventional techniques. Optimum lead placement may constrained by coronary venous anatomy and may overlie scarred heart muscle or may not be at the site of latest electrical depolarisation. In a further 10% of patients, conventional left ventricular lead placement is not possible for other technical reasons. Left ventricular endocardial lead placement may overcome the limitations and allow placement to be guided by echocardiography, electrical mapping and the pattern of heart muscle scarring. We aim to investigate if targeted left ventricular endocardial lead placement improves exercise capacity, heart failure symptoms, heart function and size, heart pumping efficiency and biochemical markers of heart strain. Each parameter will be assessed independently and as part of a composite cardiac performance score. Patients with heart failure will be enrolled who require an endocardial left ventricular lead on clinical grounds as either conventional left ventricular lead implantation has technically failed or they have clinically non-responded to CRT.