Findings from the international INVEST-CTO study conclude that a two-stage strategy boosts outcomes in patients with high-risk chronic total occlusions (CTOs). In the trial that enrolled 153 patients with anatomically high-risk CTOs and used an “investment” procedure with balloon dilatation followed by a staged completion procedure 8 to 12 weeks later, procedural success was achieved in 86.7% of patients (95%confidence interval [CI], 80.3–91.7). Of particular significance was the zero in-hospital MACE events, a striking outcome given the population’s risk profile. Therapeutic options “Success rates have been too low, and complication rates too high, in complex CTOs,” said presenter Anja Øksnes, MD, of Haukeland University Hospital in Bergen, Norway. “As a consequence, operators have been less likely to offer PCI as a therapeutic option.” Dr Øksnes added during a late-breaking clinical science session on Tuesday at the Transcatheter Cardiovascular Therapeutics (TCT) 2025 conference in San Francisco. The study population was heavily comorbid, with a median age of 66 years, 42% with prior myocardial infarction, 28% with diabetes and 27% with prior coronary bypass surgery. The angiographic complexity was also high, with a median J-CTO score of 4 and 87% of patients scoring ≥3. Equally encouraging were the secondary outcomes, where procedural success, including partial technical success, rose to 90.1%, and with a second attempt, cumulative success reached 93.4%. Composite safety endpoint At 30 days, the composite safety endpoint was observed in only 4.6% of patients, with one death, one spontaneous myocardial infarction, one stroke and several isolated complications such as tamponade or bleeding. The concept of CTO “investment” procedures is not entirely new, but this is the first prospective, multicenter, investigator-initiated study to systematically test the strategy in high-risk patients. The approach minimizes procedural time, radiation, and contrast exposure during the initial attempt, while allowing operators to return later under more favorable conditions. “A planned two staged intervention provides safe and effective treatment in anatomically complex occlusions,” said Dr Øksnes. “INVEST should be considered as an initial or early strategy in the treatment of high risk CTOs.” Dr Øksnes also presented data on procedural characteristics, where the median radiation exposure during the initial investment procedure was 550 mGy compared with 1058 mGy during the completion procedure. Contrast use was 100 ml in the investment stage and 140 ml at completion, while procedure durations averaged 61 minutes and 124 minutes, respectively. Baseline characteristics of the cohort reflected the challenge of this patient population. Nearly 70% had hypercholesterolemia, 69% hypertension and 19.6% chronic kidney disease. Angiographic features included 80% with an ambiguous proximal cap, 82% with CTO length ≥20 mm, and 44% with severe calcification. Single-arm limitations Dr. Øksnes also highlighted the limitations of the single-arm design and the fact that procedures were performed at high-volume CTO PCI centers. However, the trial’s results suggest that operators could expand access to PCI for patients who might otherwise be turned down. The INVEST-CTO trial was funded by an unrestricted grant from Boston Scientific, with angiographic core lab assessment, independent event adjudication, and oversight from a data and safety monitoring board. Image Caption: Anja Øksnes, MD, presents during a press conference Tuesday, October 28, at the Transcatheter Cardiovascular Therapeutics (TCT) 2025 conference in San Francisco. Image Credit: Screenshot by Bailey G. Salimes, CRTonline.org.