Subgroup analysis
Subgroup analysis between the two groups with respect to loss of pulse pressure and left heart decompression was performed because pulse pressure plays an important role in LV decompression (Table 4). Left heart decompression did not benefit weaning off ECMO support by subgroup analysis in patients with loss of pulse pressure (28.6% vs. 16.7%, p = 0.46). Nevertheless, pulse pressure importantly affected successful weaning off ECMO support in patients that did not undergo left heart decompression (16.7% vs. 100%, p < 0.01).
A comparison of patients with or without pulse pressure showed only four of 19 patients with loss of pulse pressure were successfully weaned off ECMO support, whereas weaning was successful in ten of eleven patients with pulse pressure (21.0% vs. 90.9, p < 0.01, Figure 2). The most common cause of death among those that could not be weaned off ECMO support was multiple organ failure. Of the 19 patients with loss of pulse pressure, six lost the pulse pressure immediately after ECMO initiation, and only one of these six was successfully weaned off ECMO support. The reason for cardiac arrest in this one survivor was fulminant myocarditis, and in this patient, left heart decompression by left atrial venting was performed. Three of the remaining 13 patients that lost pulse pressure could wean off ECMO support. Cardiac arrest in these three patients was caused by variant angina, respiratory cardiac arrest, and VT from Brugada syndrome, respectively.
Eighteen patients suffered AMI and 14 of these were offered revascularization. Of these 14 patients, seven lost pulse pressure and could not be weaned off ECMO support. Six of the seven that maintained pulse pressure could be successfully weaned. The four patients that did not undergo revascularization lost pulse pressure and one of these patients was successfully weaned off ECMO.