***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND We tested the hypothesis that prophylactic cardiac-resynchronization therapy in the form of biventricular stimulation with a pacemaker with or without a defibrillator would reduce the risk of death and hospitalization among patients with advanced chronic heart failure and intraventricular conduction delays . METHODS A total of 1520 patients who had advanced heart failure ( New York Heart Association class III or IV ) due to ischemic or nonischemic cardiomyopathies and a QRS interval of at least 120 msec were r and omly assigned in a 1:2:2 ratio to receive optimal pharmacologic therapy ( diuretics , angiotensin-converting-enzyme inhibitors , beta-blockers , and spironolactone ) alone or in combination with cardiac-resynchronization therapy with either a pacemaker or a pacemaker-defibrillator . The primary composite end point was the time to death from or hospitalization for any cause . RESULTS As compared with optimal pharmacologic therapy alone , cardiac-resynchronization therapy with a pacemaker decreased the risk of the primary end point ( hazard ratio , 0.81 ; P=0.014 ) , as did cardiac-resynchronization therapy with a pacemaker-defibrillator ( hazard ratio , 0.80 ; P=0.01 ) . The risk of the combined end point of death from or hospitalization for heart failure was reduced by 34 percent in the pacemaker group ( P<0.002 ) and by 40 percent in the pacemaker-defibrillator group ( P<0.001 for the comparison with the pharmacologic-therapy group ) . A pacemaker reduced the risk of the secondary end point of death from any cause by 24 percent ( P=0.059 ) , and a pacemaker-defibrillator reduced the risk by 36 percent ( P=0.003 ) . CONCLUSIONS In patients with advanced heart failure and a prolonged QRS interval , cardiac-resynchronization therapy decreases the combined risk of death from any cause or first hospitalization and , when combined with an implantable defibrillator , significantly reduces mortality 
    Output:
    
The authors conclude that prolonged PR is associated with worse outcome in this population .
We thought that this is a crucial point as a change in risk ratio of the study by Freidman et al.3 could potentially change the overall pooled RR of the meta- analysis