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Implementing either a pharmacoinvasive strategy or or primary percutaneous coronary intervention (PCI) in the management of ST-segment elevated myocardial infarction (STEMI) result in similar outcomes, according to research published in JACC Cardiovascular Interventions.
Researchers from the University of Ottowa Heart Institute and the University of Calgary devised 2 STEMI management systems: the first, a primary PCI strategy, was designed for patients presenting to 1 of 9 hospitals within a 90 km radius of the University of Ottowa Heart Institute (zone 1); the second was a pharmacoinvasive strategy for patients presenting to 1 of 7 hospitals outside of that radius (zone 2).
All study participants (n=1216) from both zones were identified between April 2009 and May 2011. Participants had an onset of myocardial ischemic symptoms of <12 h and ST-segment elevation of ≥1 mm in 2 contiguous leads on a 12-lead electrocardiogram. All participants received 160 mg of chewable asprin and a 60 U/kg intravenous bolus of unfractioned heparin (maximum dose: 4000 U). Zone 1 participants received an additional dose of 600 mg oral clopidogrel and zone 2 patients received 300 mg oral clopidogrel (if aged ≤75 years), a 12 U/kg/h intravenous infusion of unfractionated heparin, and a weight-adjusted intravenous bolus of tenecteplase (TNK).
The primary efficacy outcome was a composite of mortality, stroke, or reinfarction within index hospitalization, and the primary safety outcome was major bleeding within index hospitalization.
More than 80% of participants were referred to the cardiac care center as part of the primary PCI group (mean age: 62.7±13.3 years); 19% were referred as a part of the pharmacoinvasive group (mean age: 61.2±11 years). The researchers observed anterior MI in 33.9% of parmacoinvasive group patients and in 40.6% of primary PCI group patients (P =.06).
Within the pharmacoinvasive group, median time from symptom onset to first hospital arrival was significantly shorter—92 minutes (interquartile range [IQR]: 55-147 min)—than the primary PCI group—97 minutes (IQR: 60-205 min; P =.03).
Median door-to-balloon time was 95 minutes for the primary PCI group and 305 min for the pharmacoinvasive group (IQR: 71-124 minutes and 228-421 min, respectively; P <.0001), with a median door-to-needle time of 31 minutes (IQR: 18-60 minutes).
Within 24 hours, coronary angiography and PCI were performed in 93.6% and 85.2%, respectively, of pharmacoinvasive patients and on 98.8% and 92.2% of PCI patients (P <.0001; P =.0007).
The primary composite outcome—mortality, reinfarction, or stroke—occurred in 6.4% of the pharmacoinvasive patients vs 7% of the PCI patients (P =.71). TIMI (thrombosis in myocardial infarction) major bleeding occurred in 4.7% of the pharmacoinvasive group and 3.2% of the PCI group (P =.26) while hemorrhagic stroke occurred in 1.3% and 0% of each group, respectively(P =.0004).
Using a multivariate analysis, researchers were able to determine that no difference between primary efficacy outcome existed between the 2 groups (odds ratio: 1.69; P =.14), although the pharmacoinvasive group had 2.15 times higher odds of TIMI bleeding (P =.06).
Overall, the results of the pharmacoinvasive strategy were associated with similar clinical outcomes when compared to the primary PCI strategy. However, the researchers noted a significantly higher risk of intracranial bleeding with the pharmacoinvasive strategy.
“The results of this study are comparable to those obtained by the Minneapolis Heart Institute (MHI) regional STEMI program, which similarly employs 2 reperfusion therapies based on distance from the PCI center,” the researchers noted. “[Their study] found that there were no differences between a pharmacoinvasive strategy and a primary PCI strategy with respect to mortality, reinfarction, stroke, or major bleeding.”
“Primary PCI remains the optimal reperfusion therapy when administered within a reasonable time,” the researchers concluded. “The use of half-dose TNK in patients ≥75 years old might be warranted to reduce the risk of intracranial bleed.”
Study Limitations
- The main limit of this study is that it is a retrospective analysis of registry data, not a randomized controlled trial. Therefore, confounding variables may have impacted results.
- Results are applicable only to regions with established STEMI programs.
Disclosures: The authors report no relationships relevant to the contents of this paper.
Reference
Rashid MK, Guron N, Bernick J, et al. Safety and efficacy of a pharmacoinvasive strategy in ST-segment elevation myocardial infarction. JACC Cardiovasc Interv. 2016 Oct 3;9(19):2014-2020. doi: 10.1016/j.jcin.2016.07.004 [Epub ahead of print].
