PCI of chronic total occlusions (CTOs) can be safely performed by expert operators and provides significant benefit to patients with reduced left ventricular ejection fraction (LVEF) or diabetes, according to a series of studies published Nov. 13 in JACC: Cardiovascular Interventions.

The studies and related editorials, which were available online before print publication, signal promise for the treatment of CTOs. Here is a rundown of the findings from three studies:

Highly experienced Japanese specialists achieve 90 percent technical success

Yoriyasu Suzuki, MD, and colleagues reported results from 2,846 consecutive patients undergoing CTO-PCI performed by 41 highly trained Japanese specialists.

Technical success was achieved in 89.9 percent of the cases, with the specialists choosing a retrograde approach in 27.8 percent of cases. Success was higher with the primary antegrade approach (91 percent) compared to the primary retrograde approach (87.3 percent), but the authors noted the retrograde approach was more likely to be used for complex lesions.

“There are still few studies to evaluate CTO strategies,” Suzuki et al. wrote. “Because the skill level of the operators strongly influences the success of CTO-PCIs, results of CTO-PCI strategies by highly skilled operators should be important to assess CTO-PCIs.”

The researchers cautioned their results may not apply to less experienced operators.

LVEF boosted in CTO-PCI patients

Researchers analyzed the clinical outcomes of 781 patients undergoing elective PCI of CTOs in a multicenter study. The patients were divided into three groups: LVEF greater than 50 percent, LVEF between 35 and 50 percent and LVEF less than or equal to 35 percent.

At two years of follow-up, the following rates of survival without major cardiac and cerebrovascular events were observed: 86 percent for the group with highest LVEF, 82.8 percent for the middle group and 75.2 percent for group with LVEF below 35 percent. The latter group increased mean LVEF from 29.1 to 41.6 percent as a result of successful PCI.

“Patients with ischemic left ventricular dysfunction (LVEF ≤35%), particularly those affected by CTOs, belong to a high-risk subset of patients, in whom the appropriate management strategy is not well established yet,” wrote lead researcher Alfredo Ro. Galassi, MD, and colleagues. “Our results showed that in experienced hands, PCI could represent a safe and efficient management strategy able to improve LVEF and symptoms, and to ensure good midterm outcome.”

The number of patients with LVEF of 35 percent or lower was relatively small—8.6 percent of the study population—but Galassi et al. noted this is reflective of real-world experience.

Outcomes of patients with diabetes

Analysis of 1,000 patients in the OPEN-CTO PCI registry—including 412 with diabetes—revealed an 83.5 percent technical success rate for diabetic patients and an 88.1 percent technical success rate for those without diabetes.

But lead researcher Adam C. Salisbury, MD, MSc, and colleagues attributed that lower success rate to more patients in the diabetes group having previous bypass surgery. After adjusting for that and other risk factors, the researchers found similar rates of technical success and periprocedural complications between groups, as well as similar improvements in symptoms and quality of life over one year of follow-up.

“Although diabetes is common in patients presenting for CTO PCI, present in 4 of 10 patients, and is associated with a greater burden of comorbidities, longer lesions, and more complex anatomy, we found no difference in the benefits of PCI on patients’ health status over the year after treatment,” Salisbury and co-authors wrote. “Although crude rates of technical success were lower in diabetics, adjustment for disease complexity, and most importantly, prior bypass surgery, eliminated the difference in technical success rates. This suggests that this observation is driven by differences in the complexity of treating CTOs in the setting of prior bypass surgery, rather than diabetes itself.”

The researchers said future studies should focus on comparing outcomes of CTO PCI, bypass surgery and medical therapy for patients with diabetes and CTOs.