Original Title: Which Intraprocedural Thrombotic Events Impact Clinical Outcomes After Percutaneous Coronary Intervention in Acute Coronary Syndromes? A Pooled Analysis of the HORIZONS-AMI and ACUITY Trials.  Reference: Jeffrey D. Wessler et al. JACC Cardiovasc Interv. 2016 Feb 22;9(4):331-7.

Courtesy of Dr. Agustín Vecchia.

Intraprocedural thrombotic events (IPTEs) indicate short and term prognosis in PCI patients. This study assessed each individual component separately to determine the relative prognostic value of each of these events. The analyzed components were: new or worsened thrombus, total vessel occlusion, no reflow / slow reflow, distal embolism and intraprocedural stent thrombosis. 6591 PCI patients from the ACUITY and HORIZONS trials were analyzed (3,428 non ST elevation MI from the ACUITY and 3,163 STEMI patients from the HORIZONS-AMI). Uninformed of the treatment and its outcomes, researchers from an independent cath lab analyzed coronary angiographies frame by frame.

Overall IPTEs rate was 7.7% (ST elevation MI was ST 12.2% vs. non ST elevation MI 3.5%). Combined events rate at 30 days for IPTEs patients was 12.7% vs 6.5% for those not presenting IPTEs (hazard ratio [HR]: 2.09, 95% confidence interval [CI]: 1.60 to 2.72; p<0.0001). As regards mortality, this was higher in IPTEs patients (4.0% vs. 1.2%, HR: 3.35, 95% CI: 2.04 to 5.50; p<0.0001). IPTEs also increased definite and probable thrombosis rate at 30 days (4.2% vs. 1.7%, HR: 2.49, 95% CI: 1.56 to 3.98; p <0.0001) and bleeding rate not associated to surgery (10.6% vs. 5.3%, HR: 2.06, 95% CI: 1.54 to 2.75; p <0.0001).

Out of 507 IPTEs patients, the observed event frequency was: non reflow/ slow reflow, 58%; new /worsened thrombus, 35.3%; distal embolization, 34.9%, abrupt vessel closure, 19.8%; and Intraprocedural stent thrombosis, 9.5%. There were more event post stent implantation than prior to it: 68.0 vs. 51.2%. 57% of patients had only one IPTE, 23% had 2 and 20% more than 2.

Each ITPE component was independently associated with events at 30 days. In addition, in multivariable analysis, each individual event was independently associated to events at 30 days, major bleeding and death. Despite in-stent thrombosis was the least frequent of events, it showed the strongest association: for combined events HR: 7.51 (CI 95% 4.36 to 12.94), major bleeding HR: 4.47 (95% CI: 2.44 to 8.20) and death HR: 7.47 (CI 95% 3.21 to 17.39).

Conclusion
The occurrence of Intraprocedural thrombotic events was not infrequent in high risk PCI patients undergoing acute coronary syndrome and thrombotic events are associated to the worst prognosis. In stent thrombosis is the least frequent thrombotic event but the one with the strongest association to the worst prognosis.

Editorial Comment
This is one of the few studies assessing individual thrombotic components normally considered as a group in randomized studies (e.g. target lesion failure). Individualizing events help us better understand the underlying mechanisms that justify the worst prognosis in these patients and accordingly design prevention strategies e.g.: the CHAMPION-PHOENIX trial on cangrelor vs. standard treatment, showed a significantly lower stent thrombosis rate, which would justify, at least partly, the trial’s positive outcomes).

IPTEs occurrence rate is not low (1 every 13 patients) and Intraprocedural stent thrombosis have the worst prognosis.

As negative points, the studied populations are slightly different between them, which means a higher percentage of randomized patients to the ‘bivalirudin alone’ group. Patients with and without ST elevation MI were not differentiated.

Last but not least, the following study will give us the tools to change the way we consider applying new treatments: today, target lesion failure has become so rare (more than 90% patients at present will not present Intraprocedural thrombotic events) that massive treatment administration (as was the case of thrombus aspiration) may not result effective and, therefore, it is important to treat the group of patients presenting events we can prevent.

Courtesy of Dr. Agustín Vecchia.