Delayed Defibrillation After In-Hospital Cardiac Arrest Cuts Survival Sharply

Delayed Defibrillation After In-Hospital Cardiac Arrest Cuts Survival Sharply

ANN ARBOR, Mich., Jan. 2 -- Delaying defibrillation by more than two minutes for patients who have a cardiac arrest in the hospital increased mortality significantly, investigators here have found.

The delay almost halved the likelihood of survival to discharge compared with patients who had defibrillation within two minutes of arrest, Paul S. Chan, M.D., of the Mid-America Heart Institute in Kansas City, and colleagues reported in the Jan. 3 issue of the New England Journal of Medicine.

Moreover, increasing time to defibrillation had a significant graded association with lower survival (P<0.001).

"We found that delays in the time to defibrillation are common in hospitalized patients with cardiac arrest due to ventricular arrhythmia," said Dr. Chan, formerly of the University of Michigan, and co-authors. "In our analysis, such delays were associated with substantially worse clinical outcomes, with each additional minute of delay resulting in worse survival."

In-hospital cardiac arrest has an estimated survival to discharge of less than 30%. Current recommendations call for defibrillation therapy within two minutes of the onset of ventricular fibrillation or pulseless ventricular tachycardia.

Previous studies have suggested an association between time to defibrillation and survival, the authors noted. However, most studies included cardiac arrests not amenable to defibrillation, confounding the results.

Dr. Chan and colleagues examined the frequency of delayed defibrillation after in-hospital cardiac arrest and the relationship between time to defibrillation and survival. For the study, they used data from the national Registry of Cardiopulmonary Resuscitation, which uses standardized definitions for process of care and outcomes during in-hospital cardiac arrest.

The analysis revealed 6,789 patients who had cardiac arrest due to VF or pulseless VT in 369 hospitals. The median time to defibrillation was one minute and ranged from less than one minute to more than six minutes.

Return of spontaneous circulation occurred in 4,168 (61.4%) patients, and 3,372 (49.7%) survived for 24 hours after cardiac arrest. Overall, 34.1% of patients survived to discharge.
Delayed defibrillation (more than two minutes) occurred in 2,045 (30.1%) patients. Survival to discharge was 22.2% in patients with delayed defibrillation versus 39.3% in patients who had more rapid defibrillation (P<0.001).

The adjusted odds ratio for survival to discharge ranged from 0.84 for defibrillation at three minutes versus one minute to 0.27 for patients who had defibrillation more than six minutes after cardiac arrest.

Delayed defibrillation significantly reduced the likelihood of return of spontaneous circulation and survival to 24 hours (P<0.001). Among patients surviving to discharge, delayed defibrillation significantly decreased the likelihood of discharge with no major disabilities in neurologic or functional status (P=0.02).


Factors significantly associated with delayed defibrillation were:


Black race
After-hours cardiac arrest
ICU bed or bed with telemetry monitoring
Smaller hospital size (fewer than 250 beds)
Medical or surgical cardiac admitting diagnosis


The authors noted several limitations of the study: the observational nature of the study; use of hospital records to determine time of arrest and defibrillation; and missing data on neurologic and functional status of 16% of patients surviving to discharge.

In an accompanying editorial, Leslie A. Saxon, M.D., of the University of Southern California in Los Angeles, noted that bystander use of publicly available automatic external defibrillators is associated with survival exceeding 50%.

"It is disappointing that survival after ventricular tachycardia or ventricular fibrillation in hospitalized patients is much less likely than that in persons in a public place, although certainly patients in hospitals are likely to be sicker than those in an airport or a casino," Dr. Saxon stated.

Most of the factors associated with delayed defibrillation can be mitigated by more effective monitoring and response, Dr. Saxon added. However, the associations with black race and small hospital size, if real, "raise concerns beyond the adaptation of monitoring technology."

The study should "refocus some of our attention on improving outcomes for hospitalized patients, especially those who have in-hospital ventricular tachycardia or ventricular fibrillation," Dr. Saxon concluded.