Implantable cardiac resynchronization therapy and defibrillator (CRT-D) in patient with heart failure

In Italy, cardiovascular disease is a leading cause of mortality, morbidity, and disability. Among all cardiovascular diseases, a prominent role is played by heart failure (HF), with 600,000 people suffering from heart failure. It is estimated that the frequency of this condition will double with each decade of age. The limited cardiac reserve of HF patients is also critically dependent on atrial contraction, synchronized contraction of the left ventricle, and a normal interaction between the right and left ventricles. The goals of treatment in patients with established HF are to relieve symptoms and signs (e.g. oedema), prevent hospital admissions, and improve survival. Patients still symptomatic on optimal medical therapy should be considered for electrical device (cardiac resynchronization therapy – CRT-P). Some inviduals with a history or arythmia may also benefit from defibrillation to prevent suddent death. 

We reviewed the evidence on effectiveness, harms and cost effectiveness of intra cardiac defibrillators with resynchronising devices (CRT-D) compared to each intervention alone (ICD, CRT-P) in people with hearth failure (QRS >120 msec and low EF). We indentified 1,116 titles and included 8 systematic reviews and 34 primary studies. We privileged evidence from recent large systematic reviews whose methodological quality was high according to the AMSTAR instrument. 

Despite the development of drug therapy, prognosis of patients with HF has not improved much. Those more likely to benefit from CRT-D insertion are those with mild to moderate heart failure. The individual patient meta-analysis by Chen et al considered the major studies comparing CRT-D versus ICD and investigated these series through analysis conducted for subgroups according to NYHA class, duration of follow-up, and design of the study. The study by Chen et al shows a significant superiority of CRT-D on ICD in reducing hospitalizations for heart failure and improvement in functional class in all subgroups. Additional recent evidence shows efficacy of CRT-D in bundle branch block but not in the other conduction disturbances. At present there is no clear evidence about the effectiveness of CRT-D in patients with atrial fibrillation (AF) or for those with near normal QRS. The MADIT-CRT and RAFT studies show a higher incidence of procedural complications such as pneumothorax, device-related infections, pocket hematoma, catheter problems in the CRT-D group than in the ICD. Chen et al report the significant increase in the dislocation of catheters and dissection of the coranary sinus. Although these complications have not been fatal, they have increased the duration of hospitalization and decreased the quality of life. Our preliminary observations are not dissimilar from those made by the NICE appraisal committee in it’s recent preliminary guidance document “Implantable cardioverter defibrillators and cardiac resynchronisation therapy for arrhythmias and heart failure” (review TA95 e TA 120, June 2014).. Best evidence suggests that CRT-D is not dominant compared to 15 

CRT-P. The most recent studies comparing ICD with CRT-D come to different conclusions, possibly because of the less serious type of patients included in the studies.