Distal protection reduces no-reflow phenomenon among select PCI patients
Intravascular ultrasound may help identify patients who will benefit most from distal protection during percutaneous coronary intervention (PCI), according to a new study published in JACC: Cardiovascular Interventions.
Among 194 patients with attenuated plaque at least 5 millimeters long observed on a pre-PCI ultrasound, those randomized to PCI with a filter-based distal protection device showed a lower incidence of no-reflow phenomenon (26.5 percent) versus those randomized to conventional PCI (41.7 percent). No-reflow phenomenon was defined as impaired perfusion—TIMI flow grade 0 to 2—even after the mechanical obstruction in the vessel had been opened with a stent.
In addition, in-hospital cardiac arrest or cardiogenic shock occurred in 5.2 percent of patients in the conventional treatment arm but none of those receiving distal protection.
“The present study demonstrated that the use of a filter-based distal protection device decreased the incidence of no-reflow phenomenon and serious in-hospital adverse cardiac events after revascularization compared with conventional PCI in patients with ACS (acute coronary syndromes) with attenuated plaque ≥5 mm in length,” wrote lead author Kiyoshi Hibi, MD, and colleagues. “We should evaluate the potential long-term effects of distal protection devices during PCI in patients with ACS at high risk for distal embolization.”
No-reflow phenomenon caused by embolization of atherosclerotic debris has been linked to greater infarct size and increased short- and long-term mortality after ST-segment elevation myocardial infarction (STEMI), Hibi and coauthors noted. However, previous randomized trials of distal protection devices to guard against this process have failed to show an improvement in outcomes.
But this study suggests attenuated plaque of at least 5 mm may identify patients at higher risk of distal embolization—and therefore more likely to benefit from the protective filters.
The authors noted their results may have been influenced by a study protocol that “strongly encouraged” aspirating floating debris immediately after stent implantation when the filters were used. This may have contributed to the wide gap in aspiration between the treatment groups—67.4 percent of patients receiving distal protection versus 12.5 percent undergoing conventional PCI.
“The difference might have affected the primary or secondary endpoints. Therefore, our strategy in the distal protection group may represent a combination strategy of distal filter protection and aspiration rather than distal filter protection alone,” the researchers wrote.
The authors acknowledged they used a “highly selected” group of patients based on plaque characteristics, and cautioned against applying their results to a broader population. In addition, the number of in-hospital events was relatively small, which limits the power of that comparison.
However, the same research group previously showed that attenuated plaque of at least 5 mm was present in 12.4 percent of STEMI patients and may also be present in a smaller proportion of patients with other acute coronary syndromes.
In a related editorial, a pair of researchers from Wakayama Medical University in Japan pointed out intravascular ultrasound (IVUS) is used far more often to guide PCI in their country than the United States. Previous estimates put IVUS use at 80 percent for all PCIs in Japan and only 10 percent in the U.S., they said.
“The VAMPIRE 3 study (by Hibi et al.) is an important study showing the clinical significance of IVUS guidance in PCI,” wrote Takashi Kubo, MD, PhD, and Takashi Akasaka, MD, PhD. “IVUS assessment before PCI is a prerequisite for getting benefit from distal protection.”
Even so, the editorialists said distal protection only works in specific cases—not for bifurcation lesions, tight lesions or tortuous or calcified vessels.
Daniel joined TriMed’s Chicago editorial team in 2017 as a Cardiovascular Business writer. He previously worked as a writer for daily newspapers in North Dakota and Indiana.