Risk-adjusted survival rates for patients who experienced cardiac arrest in a hospital intensive care unit or inpatient ward increased every year between 2000 and 2009, according to a recent study. "There are about 160,000 in-hospital deaths from cardiac arrest every year," co-author Paul S. Chan, MD, of Saint Luke's Mid America Heart Institute in Kansas City, Mo., told Cardiovascular Business. "[It is] a hidden epidemic, and people don't have a good appreciation of its impact."

The study was published Nov. 15 in the New England Journal of Medicine.

Corresponding author Saket Girotra, MD, of the division of cardiovascular disease at the University of Iowa Hospitals and Clinics in Sioux City, and colleagues sought to identify trends in survival of in-hospital cardiac arrest, both acute resuscitation survival (rate of return of spontaneous circulation for at least 20 minutes post-arrest) and survival to discharge. They also evaluated the neurological condition of survivors at time of discharge.

The researchers examined the records of 84,625 patients over the age of 18 with an index cardiac arrest between Jan. 1, 2000, and Nov. 19, 2009, in one of 374 hospitals participating in the Get With The Guidelines-Resuscitation registry. The analysis excluded data from hospitals with fewer than three years of data submission to the registry or fewer than five cardiac arrests annually.

The researchers noted that patient characteristics changed over time, with patients becoming younger (mean age of 67.3 years in 2000-2003 vs. 65.9 years in 2009), and exhibiting less baseline heart disease and neurological impairment. Most patients were male and white. The incidence of septicemia, use of mechanical ventilation and use of intravenous vasopressors prior to cardiac arrest increased over the study period.

They reported the risk-adjusted rate of survival to discharge was 17 percent overall, but ranged upward from 13.7 percent in 2000 to 22.3 percent in 2009. Acute resuscitation survival increased from 42.7 percent in 2000 to 54.1 percent in 2009, and post-resuscitation survival increased from 32 percent in 2000 to 42.9 percent in 2009.  

A prior study showed no temporal improvement in survival rates for in-hospital cardiac arrest between 1992 and 2005 (N Engl J Med 2009;361:22-31). However, Chan pointed out that this study was based on Medicare data and examined patients who were undergoing cardiopulmonary resuscitation (CPR), as indicated by CPT codes. Some patients who receive CPR are not in cardiac arrest, he explained. The data available in the GWTG-Resuscitation registry assures that the researchers examined only survival rates of cardiac arrest patients.

"We saw marked improvement in both acute resuscitation survival and survival to discharge," Girotra said in an interview. "Also, and very significant, is that most patients who survived to discharge left the hospital with no or minor neurologic disability.”

The study found that in 2000 half of the patients who survived to discharge suffered clinically significant or severe neurologic disability; by 2009, that number had dropped to 38.8 percent.

"We wanted to unravel what may be driving these very marked improvements," Girotra said.  "But our data do not have sufficient granularity to pinpoint the mechanisms of these favorable trends."   

The researchers cautioned that because their data came from the GWTG-Resuscitation registry, it is possible that reporting institutions gave resuscitation procedures a higher priority and achieved better results.

Girotra et al are planning to continue to study in-hospital cardiac arrest survival by focusing on the best performing institutions. "We need to dig deeper and try to identify discrete, concrete actions that lead to better outcomes," Chan said.

As with door-to-balloon times for STEMI patients, the researchers said that collecting both hard data and qualitative data on the survival of in-hospital cardiac arrests can lead to advances in quality of care and long-term outcomes.

"It's a three-step process," Chan said. "First, we have to see if we are doing better. This study shows that we are. Then we need to focus on the high performers, to learn what they are doing well ... And if we find that there are specific things that are leading to these better results, then we have to disseminate that information to improve care for everyone, at every hospital."