Very Early Versus Delayed Angiography +/- Intervention on Outcomes in Patients With NSTEMI

Background: Clinical event rates in Non ST elevation myocardial infarction acute coronary syndrome (N-STEMI ACS) patients remain high, with one year MACE rates as high as 20%. While there may be early mortality differences between N-STEMI and STEMI, outcomes beyond one year become very similar. N-STEMI ACS patients therefore rightly remain the focus of a number of research directives. The objective of the RAPID-NSTEMI trial is to determine if clinical outcomes can be improved by very early intervention in a pre-determined higher risk N-STEMI ACS population. Published data has shown that inpatient Percutaneous Coronary Intervention (PCI) in N-STEMI ACS patients reduces subsequent clinical events. This had led to guidelines supporting its use in clinical practice. However, there is much less certainty regarding the timing of the PCI and, in particular, whether this should be a strategy used early to optimize outcomes. Thus, while evidence based guidelines (NICE and European) provide general time parameters for PCI, immediate angiography with a view to intervention in higher risk patients has never been robustly tested in any adequately powered, prospective randomised trial with clinical end points. The RAPID-NSTEMI trial sets out to test the benefits, or otherwise, of a strategy of immediate angiography with follow-on revascularisation in higher risk N-STEMI ACS patients.

Hypothesis: Very early angiography +/- PCI improves clinical outcomes in higher risk NSTEMI patients when compared to standard invasive management.

Methods: In order to identify higher risk patients as soon as possible after presentation, a high sensitivity troponin (Hs-Troponin-T or Hs-Troponin-I) will be taken, allowing calculation of a GRACE 2.0 score (GS 2.0) early after admission. The GS 2.0 will be determined in sufficient time to be able to test an early intervention strategy arm. Patients with GS 2.0 of ≥118 alone, or ≥90 with additional high risk features will be randomised in a 1:1 fashion to one of two groups:

Group A: immediate angiography with follow-on revascularisation if required Group B: standard care - pharmacological treatment until angiography with follow on revascularisation if required (preferably within 72 hours as per current guidelines).

The primary outcome for the main study will be a 12-month of all-cause mortality, new myocardial infraction and hospital admission with heart failure.

Power calculations indicate that 2314 patients are required to show MACE superiority for early intervention in such higher risk N-STEMI ACS patients.

Analyses will be primarily according to "intention to treat", with a secondary analysis according to trial treatment received (comparing those who actually received follow-on revascularisation at the two different trial time points). There will be a cost effectiveness analysis.

Mechanistic sub-studies in the two groups will be undertaken.

1. Cardiac magnetic resonance imaging substudy to assess differences in infarct size, oedema, microvascular obstruction and left ventricular ejection fraction between the two arms.
2. Novel biomarkers substudy that will be funded separately after appropriate funding applications

Expected value of results: The investigators have designed a superiority trial to anticipate that outcomes will be improved in higher risk patients revascularised very early after presentation with N-STEMI. Irrespective of outcome, this trial should determine whether there is a need for a change in current patient management of a common condition and, in particular, if all N-STEMI patients should be admitted to a PCI-capable hospital to allow for very early intervention. The results will inform national and international guidelines. The planned cost effectiveness analysis will become particularly important if clinical outcomes are no different between groups since length of stay should be different.