Benefits in NNT
No one was helped (no death prevented)
No one was helped (good neurological outcome)
Early vs. Delayed Coronary Angiography after out-of-Hospital Cardiac Arrest without ST-Segment Elevation
Early angiography in patients with OHCA without ST-elevation does not improve survival or chance of good neurological outcome
Harms in NNT
Similar risk of harm between early and delayed intervention
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Source
Davila E, Chirayil J, Silverberg M. Early versus delayed coronary angiography after out‐of‐hospital cardiac arrest without ST‐segment elevation. Academic Emergency Medicine. Published online July 24, 2023:acem.14774.
Study Population: 1590 patients with OCHA randomized to early coronary angiography or delayed angiography enrolled in six randomized controlled trials
Study Population: 1590 patients with OCHA randomized to early coronary angiography or delayed angiography enrolled in six randomized controlled trials
Efficacy Endpoints
Mortality, good neurological function
Harm Endpoints
Adverse events such as ventricular arrhythmias, major bleeding, and acute kidney injury
Narrative
Less than 40% of patients with out-of-hospital cardiac arrest (OHCA) with return of spontaneous circulation (ROSC) survive to discharge.1 A subset of these patients will have ST-elevation on their post-ROSC electrocardiogram. Multiple guidelines recommend early angiography after OHCA for these patients after ROSC citing associations with improved survival.2, 3, 4 The benefits of early angiography after OHCA in patients without ST-elevation are less clear. Therefore, it is important to examine the available evidence for benefits and harms of early angiography after OHCA for patients without ST-elevation.
The systematic review and meta-analysis discussed here examined the safety and efficacy of early versus delayed angiography in patients without ST-elevation after ROSC.5 The systematic review included six multicenter randomized clinical trials (RCTs) with a total of 1590 patients. All trials enrolled patients with OHCA of presumed cardiac origin and excluded patients with obvious or suspected noncardiac etiology. Of the patients randomized to early angiography, 95.6% received their angiography immediately after randomization,6, 7 within 1 h of presentation,8 or within 2 h of presentation.9, 10, 11 In the delayed angiography group, 59.7% received an angiogram, ranging from within 6 h to 4 days after randomization, contingent on either evidence of neurological recovery or at the discretion of the treating physician. The outcomes of interest included mortality at longest follow-up; disability (measured by the Cerebral Performance Category or another validated scale); duration of mechanical ventilation and intensive care unit (ICU) and hospital length of stay (LOS); and adverse events including ventricular arrhythmias, major bleeding, acute kidney injury, and need for renal replacement therapy.
The pooled data for patients with OHCA without ST-segment elevation demonstrated that early angiography had no statistically significant impact on mortality compared to delayed angiography (six trials, 1590 patients, moderate quality of evidence). The difference in the rates of good neurologic outcome, ICU and hospital LOS, duration of mechanical ventilation, major bleeding, acute kidney injury, and need for dialysis were also not statistically significant between early versus delayed angiography.
The systematic review and meta-analysis discussed here examined the safety and efficacy of early versus delayed angiography in patients without ST-elevation after ROSC.5 The systematic review included six multicenter randomized clinical trials (RCTs) with a total of 1590 patients. All trials enrolled patients with OHCA of presumed cardiac origin and excluded patients with obvious or suspected noncardiac etiology. Of the patients randomized to early angiography, 95.6% received their angiography immediately after randomization,6, 7 within 1 h of presentation,8 or within 2 h of presentation.9, 10, 11 In the delayed angiography group, 59.7% received an angiogram, ranging from within 6 h to 4 days after randomization, contingent on either evidence of neurological recovery or at the discretion of the treating physician. The outcomes of interest included mortality at longest follow-up; disability (measured by the Cerebral Performance Category or another validated scale); duration of mechanical ventilation and intensive care unit (ICU) and hospital length of stay (LOS); and adverse events including ventricular arrhythmias, major bleeding, acute kidney injury, and need for renal replacement therapy.
The pooled data for patients with OHCA without ST-segment elevation demonstrated that early angiography had no statistically significant impact on mortality compared to delayed angiography (six trials, 1590 patients, moderate quality of evidence). The difference in the rates of good neurologic outcome, ICU and hospital LOS, duration of mechanical ventilation, major bleeding, acute kidney injury, and need for dialysis were also not statistically significant between early versus delayed angiography.
Caveats
This systematic review and meta-analysis summarized here has notable limitations. The included trials were unblinded, possibly introducing bias in decisions for further treatment after randomization. Despite inclusion of patients with presumed cardiac causes of cardiac arrest, there was low incidence of acute coronary occlusion in patients without ST-elevation after OHCA, ranging from 15% to 40%. In addition, the majority of nonsurvivors died of neurologic complications after the cardiac arrest, potentially biasing against angiography. Other clinically relevant factors for possible cardiac-related causes such as suggestive patient history, dynamic electrocardiographic changes, echocardiography demonstrating regional wall motion abnormalities, or serial troponin values were not considered in the trials. It is likely that certain subgroups of patients could have benefitted from the intervention more than others. However, due to insufficient data, the authors of the systematic review were not able to perform many of the preplanned subgroup analyses. Furthermore, only comatose patients were included in the RCTs, and therefore these recommendations do not apply to noncomatose patients.
Five of the RCTs reported low risk of bias. However, one of the RCTs reported a high risk of bias from deviations from intended protocol. Though the systematic review rated the outcome of mortality as moderate certainty, all other outcome measures were rated as low to very low certainty. The clinical heterogeneity among the trials, particularly in regard to timing of early and delayed angiography as well as the timing of mortality outcome measures, threatens the validity of the results of the meta-analysis. Additionally, the majority of the included studies were underpowered for their primary outcomes. Lastly, the confidence intervals for all safety outcomes were wide and could not confidently rule out the potential for harm.
In light of available evidence, early angiography following OHCA without ST-elevation after ROSC does not appear to have an effect on mortality, neurological disability, or adverse events. Larger trials with less clinical heterogeneity are necessary to improve the certainty of the conclusions and to identify possible subgroups that may benefit from early angiography. Though of moderate to very low certainty, the findings are consistent with prior meta-analysis of RCTs exploring this research question.12 Therefore, we have assigned an NNT color recommendation of red (no benefits) for early angiography for OHCA without ST-elevation post-ROSC.
The original manuscript was published in Academic Emergency Medicine as part of the partnership between TheNNT.com and AEM.
Five of the RCTs reported low risk of bias. However, one of the RCTs reported a high risk of bias from deviations from intended protocol. Though the systematic review rated the outcome of mortality as moderate certainty, all other outcome measures were rated as low to very low certainty. The clinical heterogeneity among the trials, particularly in regard to timing of early and delayed angiography as well as the timing of mortality outcome measures, threatens the validity of the results of the meta-analysis. Additionally, the majority of the included studies were underpowered for their primary outcomes. Lastly, the confidence intervals for all safety outcomes were wide and could not confidently rule out the potential for harm.
In light of available evidence, early angiography following OHCA without ST-elevation after ROSC does not appear to have an effect on mortality, neurological disability, or adverse events. Larger trials with less clinical heterogeneity are necessary to improve the certainty of the conclusions and to identify possible subgroups that may benefit from early angiography. Though of moderate to very low certainty, the findings are consistent with prior meta-analysis of RCTs exploring this research question.12 Therefore, we have assigned an NNT color recommendation of red (no benefits) for early angiography for OHCA without ST-elevation post-ROSC.
The original manuscript was published in Academic Emergency Medicine as part of the partnership between TheNNT.com and AEM.
Published/Updated
August 15, 2023