Incidence and outcomes of out-of-hospital cardiac arrest with shock-resistant ventricular fibrillation: Data from a large population-based cohort.
BACKGROUND
The increasing survival rates after out-of-hospital cardiac arrests (OHCA) are due mainly to improvements in the first 3 steps of the chain of survival. The aim of this study was to describe the temporal trends of OHCA incidence and outcomes with shock-resistant ventricular fibrillation (VF) requiring advanced life support procedures.


METHODS
All our subjects were persons aged 18 years or more who had suffered OHCA of presumed cardiac etiology, were witnessed by bystanders, treated by emergency medical service (EMS), and had VF as initial rhythm. Our study was conducted in Osaka Prefecture, Japan from May 1, 1998 through December 31, 2006. Data were collected by EMS personnel using an Utstein-style database. We evaluated the temporal trends of incidence and outcomes of shock-resistant VF.


RESULTS
During the study period, there were 8782 witnessed OHCA cases of presumed cardiac etiology. Among them, 1733 had VF as an initial rhythm, 392 of whom were shock-resistant. While the age-adjusted annual incidence of witnessed VF increased from 2.0 to 3.3 per 100,000 inhabitants, that of shock-resistant VF underwent little change during the study period. The proportion of shock-resistant VF among witnessed VF decreased from 37.0% to 19.0%. Neurologically intact 1-month survival rates after shock-resistant VF remained low at 5.6% even in 2006.


CONCLUSIONS
The actual incidence of shock-resistant VF has remained unchanged, and their outcomes continue to be dismal. Further efforts are required to reduce the mortality rates of such shock-resistant VF to achieve improved survival after OHCA.
Sakai
Tomohiko
T
Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, 2-15 Yamada-Oka, Suita City, Osaka 565-0871, Japan.
Iwami
Taku
T
Tasaki
Osamu
O
Kawamura
Takashi
T
Hayashi
Yasuyuki
Y
Rinka
Hiroshi
H
Ohishi
Yasuo
Y
Mohri
Tomoyoshi
T
Kishimoto
Masafumi
M
Nishiuchi
Tatsuya
T
Kajino
Kentaro
K
Matsumoto
Hisatake
H
Uejima
Toshifumi
T
Nitta
Masahiko
M
Shiokawa
Chizuka
C
Ikeuchi
Hisashi
H
Hiraide
Atsushi
A
Sugimoto
Hisashi
H
Kuwagata
Yasuyuki
Y
D004554:Electric Countershock; D004632:Emergency Medical Services / Q000706:statistics & numerical data*; D005260:Female; D006323:Heart Arrest / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D014693:Ventricular Fibrillation / Q000150:complications* / Q000453:epidemiology / Q000628:therapy