The American Heart Association estimates that ∼163,221 out-of-hospital sudden cardiac arrests occur annually in the United States with a median reported survival-to-discharge rate of 6.4% [ www.americanheart.org/downloadable/heart/1136822850501OutofHosCA06.pdf ]. Although rarely reported, the incidence of in-hospital cardiac arrest is thought to range between 1 and 5 events per 1000 annual hospital admissions, with a reported survival-to-discharge of 15% to 20% [Sandroni C et al. Int Care Med 2007].

However, there are wide variations in both the incidence of cardiac arrest (200%) and survival rates (500%) [Nichol G et al. JAMA 2008], noted Graham Nichol, MD, University of Washington, Seattle, WA. Although analyses are ongoing to identify potential reasons for these inconsistencies, Dr. Nichol speculated that the variability in incidence may be associated with regional variances in clinical risk factors, economic disadvantage, population density, primary/secondary prevention strategies, and, possibly, incomplete episode capture. Differences in survival rates may reflect differences in disease severity and comorbidities among the regions, as well as differences in acute treatment, including prehospital and hospital-based care. The wide variability, according to Dr. Nichol, is a reminder that communities need to monitor, report, and improve their response to cardiac arrest.

Bystander cardiopulmonary resuscitation (CPR) clearly saves lives, yet recent clinical trials show a relatively low rate of bystander intervention. Robert Berg, MD, University of Pennsylvania, Philadelphia, PA, suggested that this may be due to the complexity of “standard CPR.” Continuous chest compression CPR (CCC-CPR) has been shown to be as effective as “standard CPR” [Sayre MR. Circulation 2008], and current guidelines encourage its use in certain circumstances [AHA/ILCOR. Circulation 2000; AHA. Circulation 2005]. Dr. Berg suggested that we should improve public awareness of CCC-CPR by teaching and modeling it in public service announcements, movies, and television.

Paul Chan, MD, Saint Luke's Mid America Heart Institute, Kansas City, MO, discussed the results of a recent study that show a significant variation between hospitals in the postcardiac arrest survival-to-discharge rate. According to Dr. Chan, the only factor that appeared to predict survival-to-discharge was the hospital's defibrillation time performance, whereby hospitals in the top quartile had a survival-to-discharge OR of 1.41 versus 1.18 for those in the bottom quartile [AHA Scientific Sessions 2008; Abstract 3307]. Dr. Chan recommended additional studies to identify the practices at the hospitals that have the best defibrillation time performance, followed by the development and testing of a suite of targeted interventions based on those practices.

Restoration of adequate blood flow is critical in cardiac arrest to achieve the return of spontaneous circulation (ROSC) and improve the possibility of long-term survival. Reduced blood flow can result from inadequate compression rate or compression depth, interruptions in CPR, or delays in defibrillation after pausing chest compression. Henry Halperin, MD, Johns Hopkins University School of Medicine, Baltimore, MD, suggested that the quality of CPR could be enhanced by additional focus on adequate rate and displacement and provision of feedback to improve performance [Edelson et al. Arch Int Med 2008].

More than 50% of patients who survive resuscitation after cardiac arrest will end up in a coma or persistent vegetative state; thus, “achieving ROSC is not the final step,” said Romergryko Geocadin, MD, Johns Hopkins University School of Medicine, Baltimore, MD. Dr. Geocadin discussed therapeutic hypothermia, a pleiotropic intervention that has been shown to increase the rate of a favorable neurological outcome and reduce mortality in patients who have been successfully resuscitated after ventricular fibrillation-related cardiac arrest [Hypothermia after Cardiac Arrest Study Group. N Engl J Med 2002], as well as in coma patients after resuscitation from out-of-hospital cardiac arrest [Bernard SA et al. N Engl J Med 2002]. According to Dr. Geocadin, this therapy provides hope, and the practice of early prognostication that leads to withdrawal of life support needs to be reevaluated. When the results of both hypothermia studies were pooled, the number needed to treat (n=6) was the same as for tissue plasminogen activator (TPA) in acute ischemic stroke, suggesting to Dr. Geocadin that just as the use of TPA resulted in the creation of stroke centers, a similar type of center may be warranted for cardiac arrest.