Invasive coronary angiography after survived out-of-hospital cardiac arrest – A challenge
Decision making for invasive coronary angiography (ICA) in patients with out-of-hospital cardiac arrest is challenging. The challenges range from activation of the cath lab team when the patient is still being resuscitated in the field and the outcome is unclear to the optimal timing o catheterization in patients with survived OHCA but without ST-segment elevation on the ECG.
Current guideline recommendations suggest performing ICA in patients with survived OHCA, no other obvious cause (e.g. trauma) and diagnostic ST-segment elevations on the 12-lead-ECG or new left bundle branch block (class IB).
Patients without diagnostic ST-segment elevation ICA
In patients without diagnostic ST-segment elevation ICA should be performed if there is a high suspicion of ongoing infarction (such as the presence of chest pain before arrest, history of established CAD, and abnormal or uncertain ECG results) (class IIaB).The latter represents an important patient group as approximately 70% of OHCA survivors of suspected cardiac origin do not show ST-segment elevation (Circ Cardiovasc Interv 2010;3:200-7).
In this patient population an acute coronary occlusion may still be the cause for the OHCA but the ECG may be altered due to prolonged ischemia, intravenous drugs administered or other non-specific abnormalities.
Furthermore, it is well known that acute coronary occlusions of the left circumflex artery may not show ST-segment elevation on the 12-lead-ECG. Moreover, it has been shown that up to 60% of patients in this category undergoing ICA have a relevant coronary stenosis amenable for PCI (Circ Cardiovasc Interv 2010;3:200-7).
The advantages of performing ICA and PCI
Therefore the advantages of performing ICA and PCI in this patient group may outweigh the potential disadvantages associated with the procedure (transport to a cath lab facility, potential adverse effects of contrast such as allergic reaction or renal failure, bleeding complications, etc.). These aspects point towards an urgent need for unified recommendations regarding the decision for and the timing of ICA in patients with survived OHCA and without ST-segment elevations.
Fortunately, there are currently several trails ongoing aiming at answering this question. The TOMAHAWK study, for example, will compare immediate ICA after hospital admission in OHCA patients without ST-segment elevation to a more selective approach with potential catheterization later depending on the subsequent clinical course in a randomized, multicenter fashion.
The results of these studies will help to improve patient care and hopefully improve outcome.