I spent part of the morning at a session on outcomes for patients with acute coronary syndromes.
It’s accepted that door-to-balloon times and door-to-needle times have a critical influence on outcomes in patients presenting with ST elevation MI (STEMI) requiring urgent reperfusion. The limitation of these measures is that they focus on only the in hospital component of the delay that patients experience in receiving such therapies and take the focus off pre-hospital components of the treatment chain.
There is an inconsistency seen in the relationship between symptom onset-to-balloon times and outcome for primary PCI in patients with STEMI that was illustrated nicely in an abstract presented by Sasha Koul from Lund. He pointed out that studies matching symptom onset-to-balloon time to measures of infarct size and outcomes have been conflicting. There are probably many reasons for this but all likely to be down to difficulty for a patient to be able to accurately estimate the time of symptom onset. In his presentation he made a strong case for the time from first medical contact (FMC) as the best measure of system performance in this regard. In nearly 14000 patients undergoing primary PCI within 6 hours of FMC there was a clearly significant increase in mortality as the FMC-to-balloon time increased above 1 hour.
This was brought into sharper focus later in the day as the results of the STREAM study presented in the third Late Breaking Clinical Trials session and published simultaneously in the NEJM (free full text here) started to filter through the meeting. In this randomised study patients with STEMI in whom primary PCI could not be performed within 1 hour of presentation thrombolysis delivered similar outcomes to those seen when going on to primary PCI. Urgent, or rescue, angioplasty was only required in about 35% of patients in whom lysis had failed with catheterisation delayed to a mean of 17 hours in the rest. So similar results, but avoiding about 2/3 of emergency procedures. There was a small increase in the risk of intracranial bleeding with lysis which was attenuated by a protocol amendment reducing the lytic dose in older patients.
What all this should do is to reignite is the debate about the best treatment strategies for patients with STEMI when the expected delay to primary PCI is going to be more than an hour.
And if the option to treat the patient before hospitalisation is available then what is really needed in order to inform this decision is a keen appreciation of local performance with regard to FMC-to-balloon time! Interesting!!!