In-stent restenosis (ISR) represents approximately 10% of all PCIs in the United States and is treated most commonly with another stent, according to Issam D. Moussa, MD, MBA. In addition, approximately 25% of patients present with acute MI, and in-hospital outcomes of patients with ISR PCI are comparable with those undergoing non-ISR PCI.

For a study published in the Journal of the American College of Cardiology, Dr. Moussa and colleagues sought to provide an analysis of the temporal trends, clinical presentation, treatment strategies, and in-hospital outcomes of patients undergoing PCI for ISR in the US.

One Out of 10 Patients

“This study provides the most comprehensive analysis of the burden of ISR in the US,” Dr. Moussa explains. “We found that despite the significant progress made in stent technology and implantation technique in the US, 1 out of 10 patients undergoing PCI has the procedure due to ISR.”

Other key findings, according to Dr. Moussa, include:

  • Counter to the perception that ISR is often benign, about 1 out of 5 patients undergoing PCR for ISR present with acute coronary syndrome.
  • Repeat stenting, with another drug-eluting stent, remains the most common therapy.
  • An increase in brachytherapy for the treatment of ISR was observed during the study period.

Researchers used a retrospective analysis of data collected by the Diagnostic Catherization and Percutaneous Coronary Intervention (CathPCI) registry of the National Cardiovascular Data Registry (NCDR) between 2009 and 2017. Of total PCI patients, those undergoing PCI for ISR lesions were identified. For comparison on in-hospital outcomes, propensity-score matching was employed.

Among the 5.1 million patients undergoing PCI, 10.6% underwent PCI for ISR lesions. The percentage of patients with bare-metal stent ISR declined from 2.6% in Q3 2009 to 0.9% in Q2 2017, and the percentage of drug-eluting stent ISR rose from 5.4% in Q3 2009 to 6.3% in Q2 2017. Patients with ISR PCI were less likely to present with non-STEMI (18.7% vs. 22.5%) STEMI (8.5% vs. 15.7%). In the propensity-matched population of patients, there were no significant differences between patients with ISR and non-ISR PCI for in-hospital complications and hospital length of stay (Figure).

More Complex Patients Receiving Coronary Stents

These findings provide practical guidance for clinicians who seek to provide expectations for patients undergoing coronary stent implantation, according to Dr. Moussa. Clinical guidelines include:

  • Communicating the potential frequency of the need for repeat intervention after initial stenting.
  • Emphasizing the importance of compliance with risk factor modification therapy and antiplatelet therapy to reduce acute ischemic events after stenting.
  • Informing patients who present with potential ISR that they will most likely need to receive another stent.

Although reducing stent strut thickness has contributed to improved outcomes after stenting, Dr. Moussa points out that this approach has reached its limits. “Current research should focus on two areas,” he says. “The first is further development of second-generation biodegradable stent technology that enables manufacturing of stents with thinner struts without compromising mechanical properties. In addition, there needs to be definitive large randomized clinical trials to evaluate the efficacy of drug-eluting balloons for treatment of ISR.”

Although one may interpret the steady rate of repeat PCI for ISR as a lack of progress, Dr. Moussa emphasizes that during the course of the study, more complex patients have been receiving coronary stents. “We hypothesize that a steady rate of the need for repeat intervention may indicate increased efficacy of stents over time, due to progress in technology and implantation technique,” he concludes.