Intraprocedural Thrombotic Event Incidence Higher in STEMI vs NSTE-Acute Coronary Syndrome

Pooled analysis of ACUITY and HORIZONS-AMI trials reveals higher incidence rates of intraprocedural thrombotic events in STEMI vs NSTE-Acute Coronary Syndrome patients.

Intraprocedural thrombotic event (IPTE) incidence was higher among patients with ST-elevation myocardial infarction (STEMI) vs those with non-ST-elevation acute coronary syndrome (NSTEACS) who received percutaneous coronary intervention (PCI), according to the results from a pooled analysis of the ACUITY and HORIZONS-AMI trials.

The analysis results, published in JACC: Cardiovascular Interventions, indicate that the overall incidence of IPTE was 7.7% with components including death, major bleeding, and major adverse cardiac events (MACE). The incidence in STEMI patients was 12.2% compared with 3.5% in NSTEACS patients.

Patients also experienced no-reflow/slow reflow (58%), new/worsened thrombus (35.3%), distal embolization (34.9%), abrupt closure (19.8%), and intraprocedural stent thrombosis (IPST; 9.5%). Each separate incident was independently associated with 30-day death, major bleeding, and MACE in multivariable models, with IPST being the strongest association (MACE, hazard ratio [HR]: 6.21; confidence interval [CI]: 3.63-10.59; P<.0001).

Despite the fact that IPST occurred in less than 10% of all IPTE events, it was the incident with the strongest association with adverse events (HR: 7.51; 95% CI: 4.36-12.94).

In the combined cohort, 3428 patients had NSTEACS from the ACUITY trial and 3173 had STEMI from the HORIZONS-AMI trial. Patients who experienced IPTE had lower prevalence of diabetes, hypertension, previous MI and PCI, and previous coronary artery bypass grafting (CABG). They were, however, more likely to have elevated baseline cardiac biomarkers. Patients who did not experience IPTE had previously used thienopyridines more frequently while patients who did have IPTE had been previously randomized to bivalirudin vs heparin and glycoprotein IIb/IIIa inhibitor (GPI).

IPTE patients had significantly higher 30-day rates of MACE (12.7% vs 6.5%; HR: 2.09; 95% CI:1.70-2.72; P<.0001) and death (4.0% vs 1.2%; HR: 3.35; 95% CI:2.04-5.50; P<.0001).

Additionally, definite or probable stent thrombosis 30-day rates significantly increased in patients with IPTE (4.2% vs 1.7%; HR: 2.49; 95% CI: 1.56-3.98; P<.0001) as well as non-CABG major bleeding (10.6% vs 5.3%; HR: 2.06; 95% CI: 1.54-2.75; P<.0001). Target vessel revascularization also increased, but not as severely (3.8% vs 2.2%; HR: 1.84; 95% CI: 1.14-2.98; P=.01).

“Previous studies have assessed components of IPTE including no-reflow, distal embolism, and IPST—demonstrating worse clinical outcomes with these individual events,” researchers noted. “However, no prior study has assessed the associations of multiple IPTE components at once in a large cohort.”

In the present study, IPST produced the highest risk of 30-day clinical outcomes, with HRs approximately 3-fold higher than that of other individual components. “As IPST is increasingly recognized as an important complication of PCI, this finding may have important implications for future studies of various interventions during PCI,” the authors concluded.


Wessler JD, Genereux P, Mehran R, et al. Which intraprocedural thrombotic events impact clinical outcomes following percutaneous coronary intervention in acute coronary syndromes? A pooled analysis of the HORIZONS AMI and ACUITY trials. JACC Cardiovasc Interv. 2016. doi:10.1016/j.jcin.2015.10.049.