Summary of latest available evidence on thrombectomy, STEMI pharmacology and trends in clinical usage.
The TAPAS trial, published in NEJM in 2008, was a single centre study in which 1071 STEMI patients were randomised to routine aspiration thrombectomy vs conventional therapy, with the primary end-point of myocardial blush grade (a surrogate end-point previously shown to correlate with mortality in the early days of primary angioplasty). In this trial aspiration thrombectomy was associated with a higher blush grade, indicating better reperfusion and better ST segment resolution. One year outcome data published in the Lancet also described a 3% mortality benefit, although though the original trial was not powered to determine this. A subsequent meta-analysis also showed benefit (largely driven by TAPAS) and a IIa indication for routine thrombectomy was adopted in the guidelines. However a number of negative trials followed in quick succession (TASTE, TOTAL), ultimately leading to the downgrading of this recommendation and a downward trend in usage as indicated by BCIS audit data. Ongoing issues include a potential associated increase in stroke indicated in a sub-analysis of TOTAL; both hemorrhagic and ischaemic with no clear mechanism and the potential for selection bias in the currently available data.
Current practice reflects a largely selective approach to the use of thrombectomy, reserved for particularly large thrombus burdens and other specific indications.
The debate around the most appropriate anti-thrombotic therapy to use in STEMI has been controversial and well documented. HORIZONS-AMI, published in 2008 in NEJM, demonstrated a mortality benefit with Bivalirudin over Heparin. Although a number of criticisms regarding the trial itself and broader applicability to contemporary practice (e.g. pre-potent anti-platelet era, high numbers of femoral cases etc.) have curtailed initial enthusiasm for its use, particularly in Europe. Moreover, a subsequent single-centre study (HEAT-PPCI) in the UK described higher MACE and stent thrombosis rates with Bivalirudin over Heparin.
The routine use of GPIIb/IIIa is similarly in decline in modern primary angioplasty centres.