BACKGROUND:The prevalence, treatment and outcomes of balloon undilatable chronic total occlusions (CTOs) have received limited study. METHODS:We examined the prevalence, clinical and angiographic characteristics, and procedural outcomes of percutaneous coronary interventions (PCIs) for balloon undilatable CTOs in a contemporary multicenter US registry. RESULTS:Between 2012 and 2017 data on balloon undilatable lesions were available for 425 consecutive CTO PCIs in 415 patients in whom guidewire crossing was successful: 52 of 425 CTOs were balloon undilatable (12%). Mean patient age was 65 ± 10 years and most patients were men (84%). Patients with balloon undilatable CTOs were more likely to be diabetic (67 vs. 41%, P < 0.001) and have heart failure (44 vs. 28%, P = 0.027). Balloon undilatable CTOs were longer (40 mm [interquartile range, IQR 20-50] vs. 30 [IQR 15-40], P = 0.016), more likely to have moderate/severe calcification (87 vs. 54%, P < 0.001), and had higher J-CTO score (3.2 ± 1.1 vs. 2.5 ± 1.3, P < 0.001) and PROGRESS-CTO complications score (3.9 ± 1.7 vs. 3.1 ± 2.0, P < 0.005). They were associated with lower technical and procedural success (92 vs. 98%, P = 0.024; and 88 vs. 96%, P = 0.034, respectively) and higher risk for in-hospital major adverse events (8 vs. 2%, P = 0.008) due to higher perforation rates. The most frequent treatments for balloon undilatable CTOs were high pressure balloon inflations (64%), rotational atherectomy (31%), laser (21%), and cutting balloons (15%). CONCLUSIONS:Balloon undilatable CTOs are common and are associated with lower success and higher complication rates.

Background: Balloon uncrossable lesions are defined as lesions that cannot be crossed with a balloon after successful guidewire crossing. Methods: We analyzed the association between balloon uncrossable lesions and procedural outcomes of 8671 chronic total occlusions (CTOs) percutaneous coronary interventions (PCIs) performed between 2012 and 2022 at 41 centers. Results: The prevalence of balloon uncrossable lesions was 9.2%. The mean patient age was 64.2 ± 10 years and 80% were men. Patients with balloon uncrossable lesions were older (67.3 ± 9 vs. 63.9 ± 10, p < 0.001) and more likely to have prior coronary artery bypass graft surgery (40% vs. 25%, p < 0.001) and diabetes mellitus (50% vs. 42%, p < 0.001) compared with patients who had balloon crossable lesions. In-stent restenosis (23% vs. 16%. p < 0.001), moderate/severe calcification (68% vs. 40%, p < 0.001), and moderate/severe proximal vessel tortuosity (36% vs. 25%, p < 0.001) were more common in balloon uncrossable lesions. Procedure time (132 (90, 197) vs. 109 (71, 160) min, p < 0.001) was longer and the air kerma radiation dose (2.55 (1.41, 4.23) vs. 1.97 (1.10, 3.40) min, p < 0.001) was higher in balloon uncrossable lesions, while these lesions displayed lower technical (91% vs. 99%, p < 0.001) and procedural (88% vs. 96%, p < 0.001) success rates and higher major adverse cardiac event (MACE) rates (3.14% vs. 1.49%, p < 0.001). Several techniques were required for balloon uncrossable lesions. Conclusion: In a contemporary, multicenter registry, 9.2% of the successfully crossed CTOs were initially balloon uncrossable. Balloon uncrossable lesions exhibited lower technical and procedural success rates and a higher risk of complications compared with balloon crossable lesions.