Clinical trials, however, are performed in carefully selected subjects and their results are not always applicable to the general population. Large-scale registries or surveys, on the other hand, capture data from a much more heterogeneous population and are closer to everyday clinical practice (although the applicability of the sample may be a concern).
Now, the European CRT Survey suggests that CRT does indeed reduce rates of death and re-hospitalisation among heart failure patients. Indeed, at one-year follow-up most patients who had received a CRT device considered their symptoms were better than their pre-implant assessment.
The survey - a joint initiative of the Heart Failure Association and European Heart Rhythm Association of the European Society of Cardiology (ESC) - gathered information on more than 2000 patients at 141 centres in 13 European countries. Its aim was to assess the effect of CRT on symptom severity, cardiovascular re-hospitalisation, and survival. The study population included subjects poorly represented in clinical trials but commonly admitted as heart failure patients - including the very elderly, those with atrial fibrillation, and those previously treated with a pacemaker or other cardiac device.
Analysis of the survey data showed that at, one year (average) follow-up, 81 percent reported a self-assessed improvement in their symptoms (with 16 percent no change and 4 percent a deterioration).
The survey also found that almost 25 percent of the subjects had died or been re-hospitalised within the 12-month follow-up period. This poor outcome (whose rate is consistent with that found in clinical trials - was directly associated with the diagnostic severity of the heart failure, the pre-existence of atrial fibrillation (or other heart disease), and the type of resynchronisation cardiac device implanted. Patients implanted with a pacing device only (CRT-P) had higher rates of mortality than those whose device had an additional defibrillator (CRT-D).
First author Doctor Nigussie Bogale from Stavanger University Hospital in Norway said: "This is the largest study reporting a difference in outcome between CRT-D and CRT-P. Most patients with an indication for CRT have also an indication for a defibrillator. So unless they have contraindicating co-morbidities, it is now our belief that these patients should be considered for CRT-D implantation."
The use of advanced CRT devices has gained increasing acceptance in recent years and they are now being implanted on a large scale as an adjunct to conventional drug treatment. Indeed, some reports have described the two types of devices (CRT-P and CRT-D) as a revolution in heart failure. One important study cited in the most recent guidelines on heart failure suggested implantation of an ICD was associated with a 23 percent reduction in all-cause mortality.
One study reporting in 2009 found that throughout 15 European countries the number of CRT implantations increased substantially, from 46/million in 2004 to 99/million in 2008, an increase of 115 percent. This was mainly explained by an increase in use of CRT-D devices. One study cited by many recent guidelines (MADIT-CRT) found that CRT-D decreased the risk of heart-failure events even in relatively asymptomatic patients (with a 34 percent reduction in the risk of all-cause mortality or heart failure). This European CRT Survey now suggests that benefits of this nature - in both symptoms and survival - can be replicated in routine everyday practice. However, despite the benefits and the recommendations, other studies show there is still a wide gap between those who meet the criteria for CRT and those who actually have a device implanted.
MEDICA.de; Source: European Society of Cardiology