ACUITY Substudy: Syntax Score Correlates with Stent Thrombosis in NSTE-ACS Patients

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The extent and severity of disease, as assessed by Syntax score, strongly correlates with the risk of stent thrombosis at 30 days and 1 year in patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACS) undergoing percutaneous coronary intervention (PCI), according to a substudy of the ACUITY trial published online June 17, 2014, in Catheterization and Cardiovascular Interventions

Methods
In the main ACUITY (Acute Catheterization and Urgent Intervention Triage strategY) trial, published in the New England Journal of Medicine in 2006, 13,819 NSTE-ACS patients undergoing an early invasive strategy were assigned to 1 of 3 antithrombotic regimens: unfractionated heparin or enoxaparin plus a GPI, bivalirudin plus a GPI, or bivalirudin alone. 
For the substudy, Philippe Généreux, MD, of Columbia University Medical Center (New York, NY), and colleagues looked at the relationship between Syntax score and stent thrombosis in 2,627 patients from ACUITY who underwent PCI. The analysis included only patients from the PCI subgroup in whom quantitative coronary angiography was performed as part of a formal substudy by blinded core laboratory technicians. 


Diabetes, Syntax Score Increase Risk

Patients in the highest Syntax score (> 12) tertile were more likely to be older and male and have diabetes, renal dysfunction, baseline troponin elevation, ST-segment deviation, lower LVEF, and higher TIMI risk scores compared with the lower 2 tertiles (< 7 and 7-12). Those in the highest tertile were also more likely than those in the lower Syntax tertiles to have longer lesion lengths, thrombus-containing lesions, and severely calcified lesions. These patients also were less often prescribed a thienopyridine at discharge and treated with DES. 

The overall rate of ARC-defined definite/probable stent thrombosis was 1.1% at 30 days and 1.6% at 1 year. Thirty-day and 1-year rates of definite/probable stent thrombosis were greater in the highest Syntax tertile (2.0% and 2.8%, respectively) compared with the intermediate (0.7% and 1.1%, respectively) and lowest tertiles (0.6% and 0.7%, respectively). 

When stratified by the tertiles identified in the original SYNTAX trial, rates of definite/probable stent thrombosis at both time periods were greater in the highest (Syntax score > 32) and intermediate tertiles (23-32) compared with the lowest tertile (< 22; P < .0001 for both comparisons). 

Multivariable analysis confirmed diabetes and Syntax score to be independent predictors of definite/probable stent thrombosis at both 30 days and 1 year (table 1). 

Table 1. Multivariable Predictors of Stent Thrombosis

 

HR (95% CI)

P Value

30 Days

    Syntax Score

    Diabetes

 

1.06 (1.03-1.09)

2.93 (1.35-6.34)

 

.0004

.007

1 Year

    Syntax Score

    Diabetes

 

1.07 (1.04-1.10)

2.03 (1.06-3.89)

 

< .0001

.03


The study authors say a Syntax score cutoff of 13 may identify patients with the highest risk of stent thrombosis, “who may most benefit from more potent and/or an extended course of dual antiplatelet therapy, as well as better DES and enhanced implantation techniques (eg, with intravascular ultrasound). Conversely, abbreviated prescription regimens of dual antiplatelet therapy may be considered in patients with low [Syntax scores].” 

Dr. Généreux told TCTMD in a telephone interview that the information also may sometimes lead clinicians to choose a different revascularization strategy. 

Additionally, that thienopyridine use did not independently predict stent thrombosis may illustrate “the potential relationship between bleeding events, leading to dual antiplatelet therapy discontinuation, and the occurrence of [stent thrombosis] and [also] the relative importance of disease extension and its potential interaction with dual antiplatelet therapy noncompliance as a risk factor for [stent thrombosis],” the authors write. 

Stent thrombosis is rare in the general PCI population, but “the rate is somewhere around 7%” in those with a Syntax score of 32 or higher, Dr. Généreux said. “Those are the patients that would benefit clinically from this information.” 

Overall, he said, the findings provide another variable to consider when discussing revascularization strategy with the heart team. “Obviously there is more than just the score to look at, but it’s 1 more piece of the equation than can potentially be useful,” he added. 

 Suggestive but Not Surprising

In an email with TCTMD, Davide Capodanno, MD, PhD, of Ferrarotto Hospital (Catania, Italy), said the correlation is not surprising since patients with higher Syntax scores were more likely to receive multiple stents. 

“If you receive more stents you are obviously more exposed to the risk of stent thrombosis,” he said. “In their multivariable model, the authors did not test variables such as the number of stents or total stent length, which could have offset the prognostic significance of baseline Syntax score. Therefore, in this case, the Syntax score [may serve] as a marker of the likelihood of receiving more extensive revascularization, hence more stents.” 

Dr. Capodanno said while he would not expect operators to place fewer stents—if they were clinically indicated—because a Syntax score was high, the study may support the need for a higher level of responsibility on the part of clinicians when deciding to place a stent in a nonculprit lesion in ACS patients. 

He added that while the study authors’ hypothesis regarding the score’s potential impact on the prescribing of antiplatelet therapy is suggestive, it needs to be verified in a more contemporary scenario, “otherwise any speculation may sound overstated.” Most ACUITY patients received first-generation DES, with a smaller proportion receiving BMS, Dr. Capodanno said. He also pointed out that patients in the trial received only clopidogrel, “which no longer represents the standard of care for antiplatelet therapy in ACS.” 

To explore the study authors’ hypothesis further, “it would be important to look at the complex interplay between Syntax score on one side and discontinuation/disruption of antiplatelet therapies on the other side,” he concluded. 

Note: Several coauthors of the study are faculty members of the Cardiovascular Research Foundation, which owns and operates TCTMD. 

 


Source:
Yadav M, Généreux P, Palmerini T, et al. SYNTAX score and the risk of stent thrombosis after percutaneous coronary intervention in patients with non-ST-segment elevation acute coronary syndromes: an ACUITY trial substudy. Cath Cardiovasc Interv. 2014;Epub ahead of print. 

Disclosures:  

  • Dr. Généreux reports receiving speaker fees from Abbott Vascular. 
  • Dr. Capodanno reports no relevant conflicts of interest. 

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