By Jeffrey Zimmet, MD, PhD
Associate Professor of Medicine, University of California, San Francisco; Director, Cardiac Catheterization Laboratory, San Francisco VA Medical Center
Dr. Zimmet reports no financial relationships relevant to this field of study.
SYNOPSIS: A new study shows that increased percutaneous coronary intervention procedural complexity helps risk stratify patients and correlates with the benefit of longer-term dual antiplatelet therapy.
SOURCE: Giustino G, Chieffo A, Palmerini T, et al. Efficacy and safety of dual antiplatelet therapy after complex PCI. J Am Coll Cardiol 2016 Aug 25. pii: S0735-1097(16)34935-X. doi: 10.1016/j.jacc.2016.07.760. [Epub ahead of print].
Choosing an appropriate duration of dual antiplatelet therapy (DAPT) following coronary intervention with drug-eluting stents (DES) involves weighing competing risks of ischemic and thrombotic events with those of serious bleeding. Over the past several years, a bevy of trials has examined this issue at both the short and the long ends of the scale. Multiple studies, including ISAR SAFE, ITALIC, and OPTIMIZE, have investigated the minimum DAPT duration, comparing one year of DAPT with shorter durations of therapy in the range of three to six months. These individual studies have, for the most part, confirmed the safety of newer DES, and led to the recent change in U.S. guidelines reducing the DAPT duration for non-acute coronary syndrome, post-percutaneous coronary intervention patients to six months. At the opposite pole, the DAPT, DES LATE, and PEGASUS TIMI 54 trials have assessed the results of DAPT duration beyond 12 months, demonstrating a tradeoff between reductions in stent thrombosis and ischemic endpoints and an increase in clinically significant bleeding. Tools such as the DAPT score have attempted to individualize therapy by applying event- and patient-level characteristics to the risk-benefit equation.
The recent study by Giustino et al takes this individualized approach one step further, linking PCI complexity with downstream events and with the potential benefits of longer-term DAPT. The authors combined patient-level data from six randomized, controlled trials comparing short (three or six months) and long (≥ 12 months) post-PCI DAPT duration. They developed and operationalized the definition of “complex” PCI, which includes any of the following: treatment of three or more lesions, treatment of three or more vessels, use of at least three stents or a total stent length > 60 mm, stenting of a chronic total occlusion, or treatment of a bifurcation with two stents. Of the 9,577 patients from the pooled trials, 1,680 (17.5%) presented with characteristics of complex PCI. Newer-generation stents were used in approximately 86% of the study population.
Compared with the non-complex population, patients in the complex PCI category experienced significantly higher rates of major adverse cardiac events (MACE), as well as of coronary thrombotic events, myocardial infarction (MI), and stent thrombosis. Patients with higher numbers of complex PCI characteristics experienced higher MACE rates; among these characteristics, bifurcation PCI with two stents was most strongly associated with increased ischemic risk.
In the complex PCI group, long-term DAPT showed a significant reduction in MACE (adjusted hazard ratio [HR], 0.56; 95% confidence interval [CI], 0.35-0.89) that was not evident in the non-complex PCI group (adjusted HR, 1.01; 95% CI, 0.75-1.35; P for interaction = 0.01). Furthermore, the magnitude of this benefit increased with the number of high-risk procedural features. As expected, the risk for significant bleeding was higher in the long-term DAPT group, regardless of PCI complexity.
The authors concluded that DAPT for ≥ 1 year carried a significant benefit in terms of risk of cardiac ischemic events, compared with three or six months of DAPT, specifically in patients who underwent complex PCI. The perceived benefits of longer-term DAPT were greater as the degree of procedural complexity increased.
COMMENTARY
Much of the discussion of DAPT in the past year has focused on the safety of shorter duration of therapy with newer DES platforms. Identifying patients who will benefit from longer-term treatment has been limited to tools such as the DAPT score, which uses patient age, diabetes status, recent smoking history, PCI or MI history, presence of chronic heart failure or reduced ejection fraction, and index procedural characteristics, including MI at presentation, vein-graft PCI, and stent diameter. Overall, these are relatively blunt instruments and ignore most of the characteristics of the procedure itself.
Here, the authors convincingly identified PCI procedural complexity as a predictor of both downstream adverse events and of concrete benefit to long-term DAPT. This validates a strategy that many interventionalists have followed instinctively for some time, identifying a population for whom the risk-benefit ratio favors longer-duration antiplatelet therapy.
These anatomic and procedural characteristics provide a better surrogate for identifying risk compared with clinical factors such as age and diabetes and temper the enthusiasm for across-the-board shorter durations of therapy with concrete data. Most of all, this study demonstrates the need to fully understand a patient’s stent anatomy before making recommendations regarding duration of therapy.
A new study shows that increased percutaneous coronary intervention procedural complexity helps risk stratify patients and correlates with the benefit of longer-term dual antiplatelet therapy.
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