Evaluation of initial shockable rhythm as an indicator of short no-flow time in cardiac arrest: a national registry study

Abstract

BackgroundThe duration from collapse to initiation of cardiopulmonary resuscitation (no-flow time) is one of the most important determinants of outcomes after out-of-hospital cardiac arrest (OHCA). Initial shockable cardiac rhythm (ventricular fibrillation or ventricular tachycardia) is reported to be a marker of short no-flow time; however, there is conflicting evidence regarding the impact of initial shockable cardiac rhythm on treatment decisions. We investigated the association between initial shockable cardiac rhythm and the no-flow time and evaluated whether initial shockable cardiac rhythm can be a marker of short no-flow time in patients with OHCA.MethodsPatients aged 18 years and older experiencing OHCA between 2010 and 2016 were selected from a nationwide population-based Japanese database. The association between the no-flow time duration and initial shockable cardiac rhythm was evaluated. Diagnostic accuracy was evaluated using the sensitivity, specificity and positive predictive value.ResultsA total of 177 634 patients were eligible for the analysis. The median age was 77 years (58.3%, men). Initial shockable cardiac rhythm was recorded in 11.8% of the patients. No-flow time duration was significantly associated with lower probability of initial shockable cardiac rhythm, with an adjusted OR of 0.97 (95% CI 0.96 to 0.97) per additional minute. The sensitivity, specificity and positive predictive value of initial shockable cardiac rhythm to identify a no-flow time of <5 min were 0.12 (95% CI 0.12 to 0.12), 0.88 (95% CI 0.88 to 0.89) and 0.35 (95% CI 0.34 to 0.35), respectively. The positive predictive values were 0.90, 0.95 and 0.99 with no-flow times of 15, 18 and 28 min, respectively.ConclusionsAlthough there was a significant association between initial shockable cardiac rhythm and no-flow time duration, initial shockable cardiac rhythm was not reliable when solely used as a surrogate of a short no-flow time duration after OHCA.

Accuracy of the Initial Rhythm to Predict a Short No-Flow Time in Out-of-Hospital Cardiac Arrest

“…However, this might be explained by shorter average NFTs in their cohort (33). In a larger Japanese study, the sensitivity of the initial rhythm was much lower, but the specificity higher than that in the present analysis and the other two preceding studies, yielding a positive and negative likelihood ratio of an initial shockable rhythm to identify patients with an NFTless than or equal to 5 close to 1 (15–17). This can be explained by the much lower prevalence (12%) of shockable rhythms observed in their study, compared with the present one.…”

“…The sensitivity was higher, at the cost of a much lower specificity with increasing NFT cutoffs. These results are plausible as asystole is rarely the initial rhythm in patients with an OHCA (15,17,18).…”

“…For patients with an unwitnessed OHCA, the NFT is all the more uncertain, and this factor currently often excludes these patients from being candidates to ECPR (12)(13)(14). However, it has been proposed that the initial rhythm may help identify patients with unwitnessed OHCA who are more likely to have a short NFT, based on the observation that shockable and organized rhythms tend to deteriorate over time (15)(16)(17)(18). However, the diagnostic accuracy of the initial rhythm varied a lot between studies, and pulseless electrical activity (PEA) has also been observed in patients with short NFTs, especially in patients with an emergency medical service (EMS)-witnessed OHCA (15)(16)(17)(18).…”

A Comparison of Prognostic Factors in a Large Cohort of In-Hospital and Out-of-Hospital Cardiac Arrest Patients

“…Unlike previous prognostic models necessitating information on no-flow duration [ 42 , 43 ], our model does not require this data, making it more universally applicable. Moreover, the location of cardiac arrest showed no significant correlation with neurological outcomes or pure survival at three months, suggesting that distinguishing between IHCA and OHCA may be less crucial now than previously assumed, given the similar outcomes at three months, as reported in a previous study [ 19 ].…”