Prediction of Prehospital Change of the Cardiac Rhythm From Nonshockable to Shockable in Out‐of‐Hospital Patients With Cardiac Arrest: A Post Hoc Analysis of a Nationwide, Multicenter, Prospective Registry

Abstract

Background Predicting a spontaneous rhythm change from nonshockable to shockable before hospital arrival in patients with out‐of‐hospital cardiac arrest can help emergency medical services develop better strategies for prehospital treatment. The aim of this study was to identify predictors of spontaneous rhythm change before hospital arrival in patients with out‐of‐hospital cardiac arrest and develop a predictive scoring system. Methods and Results We retrospectively reviewed data of eligible patients with out‐of‐hospital cardiac arrest with an initial nonshockable rhythm registered in a nationwide registry between June 2014 and December 2017. We performed a multivariable analysis using a Cox proportional hazards model to identify predictors of a spontaneous rhythm change, and a ridge regression model for predicting it. The data of 25 804 patients were analyzed (derivation cohort, n=17 743; validation cohort, n=8061). The rhythm change event rate was 4.1% (724/17 743) in the derivation cohort, and 4.0% (326/8061) in the validation cohorts. Age, sex, presence of a witness, initial rhythm, chest compression by a bystander, shock with an automated external defibrillator by a bystander, and cause of the cardiac arrest were all found to be independently associated with spontaneous rhythm change before hospital arrival. Based on this finding, we developed and validated the Rhythm Change Before Hospital Arrival for Nonshockable score. The Harrell’s concordance index values of the score were 0.71 and 0.67 in the internal and external validations, respectively. Conclusions Seven factors were identified as predictors of a spontaneous rhythm change from nonshockable to shockable before hospital arrival. We developed and validated a score to predict rhythm change before hospital arrival.

Prevalence and factors associated with initial and subsequent shockable cardiac arrest rhythms and their association with patient outcomes in dogs and cats undergoing cardiopulmonary resuscitation: A RECOVER registry study

“…In this patient population, OHCA was associated with decreased odds of having both I‐SHKRs and S‐SHKRs. A possible explanation is that OHCA cases are less likely to be witnessed arrests, and in people, witnessed arrests are consistently associated with increasing odds of I‐SHKRs and S‐SHKRs 11,20–22,36 . Shockable rhythms are an energy‐demanding process and their occurrence may correspond to the availability of high‐energy phosphates that deplete over time in no‐flow states 72 .…”

“…A possible explanation is that OHCA cases are less likely to be witnessed arrests, and in people, witnessed arrests are consistently associated with increasing odds of I-SHKRs and S-SHKRs. 11,[20][21][22]36 Shockable rhythms are an energy-demanding process and their occurrence may correspond to the availability of high-energy phosphates that deplete over time in no-flow states. 72 Outcomes of OHCA in people are thought to be significantly worse due to the increased risk of progressing to a NSHKR with longer delay until CPR initiation, a factor likely to also explain the negative association with SHKRs in veterinary medicine where bystander CPR is even less commonly performed.…”

“…Conversely, monitored or witnessed cardiopulmonary arrest (CPA) and specific cardiac diseases (eg, ischemic heart disease, dysrhythmias, and valvular heart disease) have been associated with I‐SHKRs in IHCA 10 . Factors found to be associated with conversion of I‐NSHKRs to S‐SHKRs in OHCA include witnessed arrest, PEA as the initial rhythm, and a nonexogenous cause of cardiac arrest 11 …”

“…10 Factors found to be associated with conversion of I-NSHKRs to S-SHKRs in OHCA include witnessed arrest, PEA as the initial rhythm, and a nonexogenous cause of cardiac arrest. 11 In veterinary medicine, studies investigating initial cardiac arrest rhythms report a prevalence of I-NSHKRs of 61%-90% in dogs and 59%-100% in cats, and a lower prevalence of I-SHKRs of 8%-21% in dogs and 0%-16% in cats. [12][13][14][15][16] Incidence of S-SHKRs had been previously reported to be 7%-22% in dogs and 7% in cats.…”

Differences in Pathophysiology and Treatment Efficacy Based on Heterogeneous Out-of-Hospital Cardiac Arrest

“…Out-of-hospital cardiac arrest (OHCA) is a leading cause of mortality, affecting over 350,000 individuals in the United States every year [ 1 , 2 , 3 , 4 ]. Despite developments in resuscitation science, including those within the educational system [ 5 , 6 , 7 ] and in pre-hospital management [ 8 , 9 ], survival rates remain low. The 2021 European Resuscitation Council Guidelines state the following: “Survival rates at hospital discharge are on average 8%, varying from 0% to 18%” (Page 62 Paragraph 5 Line 13) [ 1 ].…”