Our study demonstrates that demographic and clinical variables available immediately post-cardiac arrest are associated with CATH. Specifically, gender, OHCA, acute ischemic electrocardiographic changes, and echocardiography are positively associated with receiving CATH after cardiac arrest. An initial rhythm of PEA, asystole, or lower than maximal eye, verbal, or motor GCS are negatively associated with receipt of CATH. These data also reveal a bias for taking patients with superior neurological status to CATH. Normal eye, verbal, and motor GCS scores are independent predictors of CATH performance. Moreover, four STEMI patients in our population did not receive CATH because of unfavorable neurological status. Importantly, Levy et al.
demonstrated that an initially poor GCS did not predict a poor neurologic outcome with certainty. 12
Prior studies have also demonstrated that the use of hypothermia after cardiac arrest improves neurologic outcome in patients who are comatose after initial resuscitation. 13, 14
Some argue that because cardiac arrest caries a high mortality from neurological, rather than cardiac sequelae, CATH should be reserved for those patients who demonstrate neurological improvement.10
Given the priority of early reperfusion to reduce morbidity and mortality,1,2,3
this practice might deprive some patients who might recover neurologically of their potential survival. Furthermore, the use of therapeutic hypothermia may confound this argument, since patients may not reveal their neurological trajectory until up to several days after return of spontaneous circulation.12, 15
A combination of these potent therapies increased the number of patients enjoying a good outcome following cardiac arrest by 30%. 7
These data should be considered when evaluating post-cardiac arrest patients for CATH and may prompt clinicians to consider its use in patients who may not traditionally receive it.
Even after adjusting for clinical factors associated with CATH performance, receiving CATH after cardiac arrest was independently associated with good neurological outcome following cardiac arrest. In these data, there was no difference in outcomes between groups receiving early and later CATH. This may be due to the small sample size. While it is generally accepted that early CATH is indicated in patients with STEMI or new LBBB, the role of early CATH in other post-cardiac arrest patients remains to be determined. One potential benefit of early CATH is the ability to define coronary anatomy, since early identification of coronary versus non-coronary causes of cardiac arrest in an otherwise undifferentiated patient would result in different therapeutic strategies. Notably, 14% of the patients in this study required IABP therapy during the post-arrest period. A significant number of patients also required coronary artery bypass grafting, left ventricular assist device, or cardiac transplantation after CATH.
A criticism of prior studies investigating the use of prompt CATH to improve survival has been extensive exclusion criteria and highly selective patient populations.4–6, 8, 16
In this study, improved survival and outcome were associated with CATH in cardiac arrest patients regardless of arrest location, presenting rhythm, presence of STEMI or new LBBB, or neurological status. CATH was independently associated with good neurological outcome.
Finally, many patients suffering cardiac arrest have significant coronary artery disease. These data agree with prior literature suggesting 60–80% of cardiac arrests are a result of cardiovascular disease.4, 8, 16, 17
Those subjects without STEMI or new LBBB also had significant coronary lesions in 56–66% of cases. These data suggest the burden of coronary artery disease is high in this population and support CATH in this population. Given that CATH is independently associated with good neurologic outcome, the high coronary artery disease burden in this population, the benefits of early reperfusion, and improved therapies for brain resuscitation following cardiac arrest, CATH should be considered along with hypothermia in all post-cardiac arrest patients.
This study has several limitations. First, it is limited to a retrospective chart review. Data could have been inaccurately reported in the patient record. Patients could have been missed, but we believe this to have been minimized by our inclusive search strategy. Third, the cohort of IHCA patients may not be representative of other hospitals, since ours has a tiered Rapid Response System with a reduced rate of IHCA.18
Finally, the outcome assessed was discharge to home or acute rehabilitation facility as a surrogate for long-term neurological status.