Successfully completing thrombus aspiration (TA) during primary PCI in STEMI patients is limited by the inability to reach and/or cross the infarct-related lesion. Researchers found that the presence of marked proximal tortuosity of the infarct-related artery, a calcified lesion and bifurcation lesions were independent predictors of failed TA. However, they noted that unsuccessful TA did not affect one-year mortality, according to a study published in this month's JACC: Cardiovascular Interventions.
“In PPCI [primary PCI], the presence of coronary thrombus has been linked to distal embolization and microvascular obstruction, reflected by lower post-procedure myocardial blush grade (MBG) and no reflow, which is associated with an increased infarct size and worse outcome,” wrote Maarten A. Vink, MD, of the Academic Medical Center, University of Amsterdam, and colleagues.
During the study, Vink and colleagues set out to determine the predictive factors and prognostic value of TA catheter failure to reach the infarct-related lesion during primary PCI in STEMI patients. To do so, Vink and colleagues analyzed 1,399 STEMI patients who underwent primary PCI at the Academic Medical Center between August 2001 and October 2007. In all cases, TA was attempted.
The researchers defined failure of TA as the inability to reach and/or cross the occlusion with the aspiration catheter for effective thrombus removal. Baseline clinical and angiographic variables related to failure of TA or lack of aspirate were examined.
Results showed that the aspiration catheter failed to cross the lesion in 10.3 percent of patients. Patients with failed TA were older and more often had multivessel coronary artery disease. Calcified lesions were more often seen in the group that experienced TA failure compared with successful TA, 33.3 percent versus 14.8 percent.
In addition, the researchers also found that marked proximal coronary tortuosity was more frequent, 67.9 percent in the failed TA group and 32.1 percent in the successful TA group. Marked proximal tortuosity of the coronary artery, the presence of a calcified lesion and a bifurcation lesion were all deemed independent predictors of unsuccessful passage of the catheter across the lesion.
The authors noted that the rates of post-procedural TIMI flow grades of less than three were observed in 13.9 percent in the failed TA group and 9.5 percent in the successful TA group. Lastly, Vink and colleagues reported that one-year mortality rates were 6.2 percent in patients with failed TA compared with 6.4 percent in patients with successful TA.
“Our analyses show that restoration of coronary flow was not influenced by failure of TA or whether thrombotic aspirate was retrieved and, importantly, no difference in one-year mortality was observed,” the authors wrote.
“Previously, the presence of marked tortuosity and coronary calcification have been identified to be predictors of failure of intravascular ultrasound imaging, at a rate of 23 percent failed procedures described in a prospective cohort of patients with stable or unstable angina,” the authors noted. The authors said that the difference in the flexibility of catheters used for intravascular ultrasound and those used for TA along with differences in patient characteristics can explain the lower failure rate during the trial.
“Failure of TA limits the ability of direct stenting but has no influence on restoration of coronary flow as compared to successful TA,” the authors concluded. Failure to reach and/or cross the lesions and absence of aspirate did not affect one-year all-cause mortality.
In an accompanying editorial, Bimmer E. Claessen, MD, and George D. Dangas, MD, PhD, both of the Cardiovascular Research Foundation and Mount Sinai Medical Center in New York City, wrote that “the clinical relevance of failed TA is still unclear.
“After the identification of predictors of TA failure, the question remains whether the failure rate can be limited.”
Clessen and Dangas suggested that improved TA devices that are developed for optimized delivery could increase success rates. In addition, this could also lead to an increased yield of thrombotic debris.
The editorialists said that a limitation of the study was the fact that TA was performed at the discretion of the operator rather than being performed routinely. “As a result, TA was only attempted in approximately one-third of primary PCIs. Ideally, we would have liked to see