DENVER – The rate of adherence to evidence-based implantable cardioverter-defibrillator programming strategies known to reduce the rate of unnecessary shocks climbed significantly in a large, prospective study in which physicians received detailed reports on their own performance and how it stacked up to that of others.
The Shock-Less study was a real-world international study involving 4,131 ICD recipients and their physicians at 118 sites. The improved adherence to evidence-based programming achieved through the use of the individualized, multipage therapy programming reports (TPRs) translated into a highly significant 27% reduction in the risk of all-cause ICD shocks during follow-up, Dr. Marc T. Silver reported at the annual meeting of the Heart Rhythm Society.
This is welcome news for patients. It means less shock-related morbidity and potentially less mortality, said Dr. Silver of WakeMed in Raleigh, N.C.
The study included 2,693 patients who received their Medtronic primary or secondary prevention ICD before a center received its first Shock-Less report and 1,438 implanted after the report. A total of 265 all-cause shocks occurred in the "before" group, 116 in the "after" cohort.
In a multivariate logistic regression analysis adjusted for factors known to affect shock rates, including patient age, smoking status, New York Heart Association functional class, and atrial fibrillation, patients in the "after" group had a 27% reduction in the relative risk of both appropriate and inappropriate shocks (P = .002).
The TPRs provided ICD centers and their individual physicians with detailed feedback on rates of adherence to nine evidence-based programming settings that help reduce shocks. Most ICDs don’t arrive from the manufacturer with these settings in place. Some of the changes in programming were quite impressive (see graphic), including a near-doubling of the rate of primary prevention ICDs programmed to 30/40 as the number of intervals to detect ventricular fibrillation; this rate improved from 18.5% to 33.1%.
Dr. Silver offered personal testimony as to the power of the TPRs as a behavior-modification tool.
Dr. Marc T. Silver
"Having received TPRs myself, it is a character-building experience. If you can get hold of information like this on your own practices, I guarantee you will leave a little smaller afterwards, like I did. Bigger in some way, smaller in others," he said.
Yet there remains a clear opportunity for further improvement in physician performance, Dr. Silver added.
"Achieving numbers in the 33% range for adherence to 30/40 [the number of intervals needed to detect ventricular fibrillation] is not what I think many of us would hope for one day," he observed.
Along those lines, audience member Dr. Thomas F. Deering of the Piedmont Heart Institute, Atlanta, commented that while the changes in physician behavior achieved through the Shock-Less project were significant, they were not sweeping in magnitude. Given the negative clinical consequences that result from lack of adherence to evidence-based programming, isn’t it time to request that the device industry change the default settings on their ICDs in accord with the evidence-based guidelines?, he asked.
"As someone who’s become very interested in physician behavior," Dr. Silver replied, "I regret to say that changing nominal settings on the devices may be the best way to move our profession forward. I say that with some degree of regret, but I think that’s the truth."
Dr. Silver reported serving as a consultant to Medtronic, which sponsored the Shock-Less study.