Public Access Defibrillation Spreading
Public access defibrillation—the use of automated external defibrillation outside of traditional emergency medical services—is becoming increasingly important, said researchers from the Seattle and King County Emergency Medical Services Division, Seattle Medic One, and the University of Washington School of Medicine in a report in this week’s issue of the journal Circulation (Circulation. 2004;109:1859–1863).
Researchers led by Michael K. Copass, MD, of the University of Washington looked at public access defibrillation in the Seattle area in a cohort study of out-of-hospital cardiac arrest cases associated with heart disease between January 1, 1999, and December 31, 2002. In this case, public access defibrillation involved treatment with an automated external defibrillator (AED) by people who are not part of traditional emergency medical services. As part of a voluntary Community Responder AED Program and a registry of public access defibrillation AEDs, more than 4000 people in the area were trained in the use of the devices as well as in cardiopulmonary resuscitation. An estimated 475 AEDs were placed in various settings over a 4-year period.
During the study period, 50 out-of-hospital cardiac arrest patients were treated by public access defibrillation before emergency medical services personnel arrived on the scene. That represented 1.33% of the 3754 cardiac arrests treated by emergency medical services personnel. The proportion of people treated by public access defibrillation increased each year, from 0.82% in 1999 to 1.12% in the year 2000, 1.41% in 2001, and 2.05% in 2002.
Half of the patients treated by public access defibrillation survived to hospital discharge.
The researchers wrote: “Given the considerable challenge of improving survival from out-of-hospital cardiac arrest, no particular strategy is likely to constitute a single best approach. Rather, efforts to strengthen each link in the chain of survival may incrementally improve outcomes. Careful surveillance and review will be an important part of assessing the potential community impact of technological, research, and programmatic advances in resuscitation. Studies to date support the use of AEDs and CPR by nontraditional responders as an approach that may improve survival from cardiac arrest. The results of this investigation suggest that the dissemination of PAD [public access defibrillation] AEDs has had a small impact in out-of-hospital cardiac arrest.”
Treating the High-Risk Patient With Long-QT Syndrome
Left cardiac sympathetic denervation should be considered in the treatment of patients with difficult-to-treat long-QT syndrome who experience recurrent syncope even when taking β-blockers or who continue to have serious arrhythmic episodes even with an implanted defibrillator, said a multinational group of investigators in the current issue of the journal Circulation (Circulation. 2004;109:1826–1833OpenUrl).
In this study, researchers led by Peter J. Schwartz, MD, of the Department of Lung, Blood, and Heart at the University of Pavia in Pavia, Italy, studied 147 such patients who had undergone the procedure. They determined that the typical patient had a very long QT interval and that almost all of them were symptomatic. Forty-eight percent of them had had a cardiac arrest, and 75% were treated by β-blockers.
After the procedure, 46% were asymptomatic. Syncope occurred in 31% and aborted cardiac arrest in 16%. Sudden death occurred in 7%. The average yearly occurrence of cardiac events dropped 91% after left cardiac sympathetic denervation, the researchers reported.
The researchers noted that although the procedure did cause significant reductions in serious events in these patients, it was not entirely effective.
Length of Stay Decreases in Acute Myocardial Infarction
The average number of days patients with acute myocardial infarction stayed in the hospital declined between 1986 and 1999, according to a report in the April 12, 2004, issue of The Archives of Internal Medicine (Arch Intern Med. 2004;164:733–740OpenUrlCrossRefPubMed).
The report noted that the average length of stay in a hospital after acute myocardial infarction is approximately 5.9 days in the United States, although there is considerable geographic variation. The study, led by Frederick A. Spencer, MD, from the University of Massachusetts Medical School in Worcester, showed that there was no increase in death rate or morbidity associated with the shorter hospital stay duration.
The researchers studied data from 4551 patients discharged after heart attack from hospitals in Worcester, Mass. During the study period, significant declines in average length of stay occurred between the periods 1986–1988 and 1997–1999.
In the earlier period, the average length of stay was 11.7 days, whereas in the latter period, it was 5.9 days. Those less likely to have a longer length of stay included patients in health maintenance organizations, those covered by Medicare and Medicaid, and those with no health insurance. There was no significant difference in mortality rates.
The researchers attributed the decrease in length of stay to improvement in management of acute myocardial infarction, including coronary reperfusion strategies.
An experimental drug called JTV519, a derivative of 1,4-benzothiazepine, appeared to protect mice prone to fatal arrhythmias caused by decreased amounts of calstabin2, said researchers in the April 9, 2004, issue of the journal Science (Science. 2004;304(5668):292–296).
The drug causes increased binding of the protein calstabin2 to the ryanodine receptor, a calcium-release channel. When calstabin binds it, the channel does not open, and no calcium is released. The experimental drug had no effect on knockout animals that had no catstabin2.
The research, led by Andrew Marks, MD, Director of the Center for Molecular Cardiology at Columbia University Medical Center, makes use of a molecular approach to treatment of heart failure. The 10 mice that received the drug did not develop an arrhythmia, whereas 8 of 9 untreated mice died after arrhythmic events.