Cardiac Resynchronization Therapy - Risk Stratification and Long-Term Outcome

Heart failure is a condition that will affect 2-3% of the population. Around one third of the patients have a decreased LVEF and a widened QRS complex as a sign of ventricular dyssynchrony. CRT has emerged as a treatment that reduces morbidity, mortality and improve functional status in this population. However, a substantial amount of treated patients do not respond satisfactory after implantation. This thesis sought to assess characteristics and factors associated with long term mortality and outcome in a cohort of CRT patients.The thesis includes four papers:Paper I assessed the association between early subjective response after implantation and long term outcome in CRT-P patients. We found that those who exhibited a self-assessed positive therapy response after 1-2 months had a significantly better survival rate compared with those who did not. The second paper investigated long term mortality in CRT-P and primary prophylactic CRT-D patients. Patients with CRT-D had better crude survival rates than those with CRT-P. However, the CRT-P group was older and had more comorbidities. CRT-D was not significantly associated with better survival when adjusting for confounders, as compared to CRT-P.The third paper assessed a method of estimating myocardial scar burden from a standard 12-lead ECG (Selvester QRS score) in patients with Left Bundle Branch Block. 401 patients were assessed and divided into a high-score and a low-score group. The group with high Selvester QRS score was found to have a worse survival rate compared to the group of patients with lower scores.The last paper found that the CHA2DS2-VASc score, which is commonly used for stroke risk estimation in atrial fibrillation patients, was associated with long term mortality and a composite endpoint of mortality or hospitalization for heart failure in a CRT population. When comparing CHA2DS2-VASc to other, CRT-specific scores, it performed approximately as well in predicting mortality and the composite endpoint