The likelihood that a patient will survive to discharge after in-hospital defibrillation for ventricular arrhythmia is dramatically higher if therapy is given within the recommended interval of two minutes after arrest, according to an article in the January 3 issue of the New England Journal of Medicine.

Analyzing data for nearly 7,000 patients in the National Registry of Cardiopulmonary Resuscitation who had documented ventricular arrhythmia, the authors concluded that 30 percent of patients received life-saving defibrillation more than two minutes after initial recognition of their arrhythmia, a delay that exceeds guidelines-based recommendations.

Delayed defibrillation was linked to a significantly lower probability of survival to hospital discharge - 22 percent versus 39 percent when defibrillation occurred within two minutes-and a 26 percent lower likelihood among survivors of being discharged without major neurological impairment.

The findings also revealed certain hospital characteristics were associated with delayed defibrillation, including small hospital size (fewer than 250 beds), occurrence of arrhythmia in patients whose heart rhythm was not being constantly monitored, and occurrence outside of regular hours (that is, nights and weekends).

"While several prior studies have shown an association between defibrillation time and survival, these were relatively small studies that typically included patients whose arrest rhythms would not have benefited from defibrillation" said lead study author Paul S. Chan, MD, a cardiologist and researcher from Saint Luke's Mid America Heart Institute. Dr. Chan was previously with the University of Michigan where he initiated the study with University of Michigan cardiologist Brahmajee Nallamothu, MD, MPH, the new paper's senior author.

"We found that delayed defibrillation was common, and that rapid defibrillation was associated with sizable survival gains in these high-risk patients," said Chan. "However, the real work has yet to be done in this field. We now have to develop systems of care within the hospital to improve defibrillation times nationally."

"These findings represent a real opportunity to improve patient care," said Nallamothu. "We need to understand how delayed defibrillation, which was more common after-hours and in unmonitored settings, relates to the immediate availability of medical personnel or equipment, as well as potential delays in recognition of ventricular arrhythmia."