Severe coronary artery calcification is associated with suboptimal stent expansion, higher complication rates and worse clinical outcomes after percutaneous coronary intervention. Several devices and techniques have been developed to facilitate the treatment of calcified coronary lesions. This manuscript outlines best practices and tips on the use of the super high pressure OPN noncompliant balloon (OPN; Swiss Interventional Systems [SIS] Medical AG, Winterthur, Switzerland).
Central Illustration: Step-by-Step Guide to the Use of the OPN balloon
Severe coronary calcification remains a major challenge in percutaneous coronary intervention (PCI), often leading to suboptimal stent expansion, higher short-term and long-term complication rates and worse clinical outcomes. ,,, Adequate lesion preparation is essential to ensure procedural success and optimal post-PCI outcomes. In cases of mild to moderate calcification, initial lesion preparation with balloon angioplasty is usually feasible; however, heavily calcified lesions often do not expand when using conventional semicompliant and noncompliant balloons. The OPN noncompliant balloon (OPN; SIS Medical AG, Winterthur, Switzerland), with its ability to reach ultrahigh pressures, can help treat heavily calcified and undilatable lesions. This manuscript outlines best practices for the use of the OPN balloon.
Description of the OPN Balloon
The OPN super high-pressure balloon is a rapid exchange percutaneous transluminal coronary angioplasty (PTCA) catheter compatible with 0.014” coronary wires. The OPN balloon has a proprietary twin-layer balloon technology, which allows very high-pressure inflations while ensuring uniform expansion without “dog-boning” over a wide range of pressures. The balloon is highly noncompliant with a nominal pressure of 10 atm and a rated burst pressure of 35 atm. Each balloon is factory tested to 45 atm. The balloon diameters currently available range from 1.5 mm up to 4.5 mm with ½ mm intervals. Lengths are 10, 15 and 20 mm ( Table 1 ) ( Figure 1 ). The commercial name OPN comes from an abbreviation of op(e)n. The OPN balloon is U.S. Food and Drug Administration (FDA)—cleared for coronary use.
Table 1
Dimensions and pressure specifications of the OPN NC balloon catheter
| Balloon diameter (mm) | Available lengths (mm) | Nominal pressure (atm) | Rated burst pressure (atm) | Min. guide catheter |
|---|---|---|---|---|
| 1.5 | 10, 15, 20 | 10 | 35 | 6 Fr |
| 2.0 | 10, 15, 20 | 10 | 35 | 6 Fr |
| 2.5 | 10, 15, 20 | 10 | 35 | 6 Fr |
| 3.0 | 10, 15, 20 | 10 | 35 | 6 Fr |
| 3.5 | 10, 15, 20 | 10 | 35 | 6 Fr |
| 4.0 | 10, 15, 20 | 10 | 35 | 7 Fr |
| 4.5 | 10, 15, 20 | 10 | 35 | 7 Fr |
OPN balloon.
The OPN balloon is indicated for the treatment of heavily calcified lesions undilatable with conventional noncompliant balloons, treatment of in-stent restenosis(ISR), and post deployment expansion of balloon-expandable coronary stents.
OPN Balloon: Clinical Studies
Several studies have reported favorable outcomes with the use of the OPN balloon ( Table 2 ).
Table 2
Published studies on OPN NC super high-pressure balloon
| First author/ Year | Study design | Population/ Sample size | Intervention | Primary outcomes | Perforation | Periprocedural death | Key findings/ Conclusions |
|---|---|---|---|---|---|---|---|
| Secco , 2016 | Retrospective study | 91 coronary lesions | OPN super high-pressure balloon (up to 40 atm) | Angiographic success (residual stenosis <30%), MLD, %DS, safety (MACE, perforation) | Νo perforations | No periprocedural death | OPN balloon achieved 92.3% angiographic success with greater luminal gain vs non-compliant balloons; no perforations or MACE at 30 days. Safe and effective alternative when conventional NC balloons fail. |
| Secco , 2019 | Retrospective study | 326 coronary lesions | OPN super high-pressure balloon (30–50 atm) | Angiographic success (residual stenosis <30%, TIMI 3 flow), procedural success, safety (MACE, rupture) | Coronary rupture in 3 cases (0.9%) | No periprocedural death | Angiographic success 97.5%, procedural success 96.6%. 53% responded at 30–40 atm, 47% required >40 atm. Coronary rupture in 3 cases, all successfully managed. OPN balloon effective in >90% of lesions; low MACE (0.9%). |
| Seiler , 2023 | Prospective registry | 208 ISR lesions in 188 patients | OPN super high-pressure balloon (>30 atm) | Procedural efficacy, periprocedural complications, TLF/TVF, MACE | 2 perforations (1.0%) | No periprocedural death | Low rate of major complications (0.96% perforation, 4% major dissections). 1-year MACE 19.7%; TVF 15.4%; MI 5.9%; stent thrombosis 2.1%; 5 deaths. Safe and potentially effective for ISR treatment. |
| Pinilla-Echeverri , 2023 | Retrospective multicenter OCT registry | 50 calcified lesions | OPN super high-pressure balloon ± other devices (NC, cutting, scoring, IVL, rotablation) | OCT-derived expansion ≥80%, calcium fractures, safety | Νo perforations | No periprocedural death | 80% lesions achieved ≥80% expansion; 98% had calcium fractures; no perforations, no-reflow or other major adverse events. Safe and effective for heavily calcified lesions. |
| Senguttuvan , 2023 | Prospective observational study | 133 lesions in 71 patients | OPN super high-pressure balloon (pre- and/or post-stent) | Procedural success, safety | 3 perforations (2.3%) | 2 deaths (2.8%): one non-cardiac due to hospital-acquired sepsis and one after balloon aortic valvuloplasty and rescue LM PCI due to acute kidney injury. | Procedural success 98.5%. 3 dissections,3 perforations, 1 stent deformation, 1 failed balloon delivery, 2 deaths. Distal shaft rupture noticed. OPN balloon safe and effective; Recommended sizing: pre-stent, undersize by 0.5 mm, optionally followed by 0.25 mm larger non-compliant balloon; post-stent, 1:1 balloon in straight non-tortuous segments |
| Rheude , 2021 | Randomized, open-label trial | 74 patients with severely calcified coronary lesions | OPN super high-pressure balloon vs scoring balloon | Stent expansion index (OCT), angiographic success, strategy & procedural success |
OPN group: 1 perforation (2.7%)
Scoring balloon group: 1 perforation (2.7%) |
No periprocedural death | Comparable stent expansion (0.72 vs 0.68; p=0.22). Super high-pressure balloon increased more the MLD (p=0.03) and reduced more the diameter stenosis (p=0.02) vs scoring balloon; trend toward improved procedural/strategy success. |
| Kumar , 2025 | Systematic review & meta-analysis | 1015 patients from 29 studies (PCI with OPN) | OPN super high-pressure balloon | Procedural success, MACE, coronary perforation, complications | 10 coronary perforation (0.6%) | 2 periprocedural deaths | Procedural success 95.1%. MACE 1.9%, coronary perforation 0.6%. High success and acceptable complication rates; heterogeneity underscores need for standardized definitions. |
| VICTORY trial, 2025 (NCT05346068, presented at TCT 2025 by Dr. Matthias Bossard) | Prospective, multicenter, randomized non-inferiority study | 278 patients | OPN super high-pressure balloon vs IVL | Final stent expansion, which was assessed using OCT |
OPN group: 2 perforations (1.4%)
IVL group: 5 perforations (3.6%) |
No periprocedural death | Final stent expansion measured was 85.0% with OPN vs 84.0% with IVL (median difference 1.0 [95% CI −2.45 to 4.45], p = 0.570 for superiority and P<0.0001 for non-inferiority). Procedural (92.03% vs 86.13%, p=0.149) and strategy (98.6% for both) success and safety profile were similar between OPN and IVL |
OPN: Super high-pressure non-compliant balloon; ISR: In-stent restenosis; MACE: Major adverse cardiovascular events; TLF: Target lesion failure; TVF: Target vessel failure; MLD: Minimal lumen diameter; %DS: Percent diameter stenosis; OCT: Optical coherence tomography; PCI: Percutaneous coronary intervention; DES: Drug-eluting stent; NC: Non-compliant balloon; IVL: Intravascular lithotripsy; OCT: Optical Coherence Tomography; VICTORY: Value of IVL Compared To OPN Non-Compliant Balloons for Treatment of RefractorY Coronary Lesions
In 2016, Secco et al. evaluated the efficacy of the OPN balloon in 91 lesions in which conventional noncompliant balloons inflated at maximal pressure failed to achieve an adequate postdilatation luminal gain and were treated with an OPN balloon up to 40 atm. Angiographic success was achieved in 84 lesions (92.3%). All of the remaining lesions were treated with rotational atherectomy except for 2 cases in which rotational atherectomy was not feasible due to small vessel size and significant tortuosity. Compared with conventional noncompliant balloon inflation, use of the OPN balloon resulted in larger minimum lumen diameter (MLD), higher acute gain and lower residual diameter stenosis (DS) (p <0.001). No coronary perforations occurred, and no acute or 30-day follow-up Major Adverse Cardiac Events (MACE) were reported.
In 2019, Secco et al. retrospectively evaluated the safety and efficacy of the OPN balloon in 326 balloon undilatable coronary lesions. Angiographic and procedural success were achieved in 97.5% and 96.6% of cases, respectively. More than half of the lesions responded to pressures between 30 and 40 atm, while nearly 47% required inflation pressures above 40 atm. Coronary rupture occurred in 3 patients and was successfully managed with stenting; 2 cases required covered stents, while the other patient was successfully treated with prolonged balloon inflation, drug-eluting stent (DES) and protamine. The OPN balloon alone achieved adequate lesion expansion in >90% of cases, with 0.9% 30-day MACE.
In 2023, Seiler et al. evaluated the use of the OPN balloon for the treatment of ISR in 188 patients with 208 lesions. The majority of lesions were severely calcified (89%) and complex (70.2%). The incidence of complications was low: coronary perforation (0.96%), major dissection (4%), no-reflow (1.9%), and acute vessel closure (0.5%). At 1-year follow-up, the MACE rate was 19.7%, target vessel failure (TVF) occurred in 15.4%, and stent thrombosis in 2.1% of patients, while 5 patients died.
Pinilla-Echeverri et al. evaluated the performance of the OPN balloon in 50 heavily calcified coronary lesions, including both superficial (50%) and nodular calcium (50%). Lesions were selected based on optical coherence tomography (OCT) criteria, including superficial calcium with arc >180° and thickness >0.5 mm, or nodular calcium with arc >90°. The OPN balloon was used either as a primary device or after using other plaque modification devices (noncompliant, cutting or scoring balloons, rotablation, or IVL). Final expansion ≥80% of the reference lumen area was achieved in 80% of cases, with a mean final expansion of 85.7 ± 8.9%. Calcium fractures were observed in 98% of cases, with multiple fractures in 74%. There were no cases of perforation, no-reflow, or major adverse events.
In 2021, in the ComparIson of Strategies to PrepAre SeveRely CALCified Coronary Lesions (ISAR-CALC) randomized trial, lesion preparation with the OPN balloon was compared with a scoring balloon in 74 patients with severely calcified coronary lesions, following initial failure with a standard noncompliant balloon (<30% reduction of baseline diameter stenosis). The OPN balloon group had significantly larger postprocedure minimum lumen diameter (2.83 ± 0.34 mm vs 2.65 ± 0.36 mm; p = 0.03) and lower residual diameter stenosis (11.6 ± 4.8% vs 14.4 ± 5.6%; p = 0.02). Strategy success (91.9% vs 83.8%; p = 0.48), procedural success (100% vs 89.2%; p = 0.12) and stent expansion index (0.72 ± 0.12 vs 0.68 ± 0.13; p = 0.22) were not significantly different between study groups.
Senguttuvan et al. prospectively evaluated the safety and efficacy of the OPN balloon in an observational study of 71 patients (133 calcified lesions). Procedural success was 98.5%. The OPN balloon was used for predilatation in 28.6% of lesions, for postdilatation in 63.2%, and both in 8.3%. Angiographic success was achieved in all lesions. Eight complications occurred, including dissections (n = 3), perforations (n = 3), stent deformation (n = 1), and failed balloon delivery (n = 1). Balloon rupture occurred in 7 cases, mainly after inflation >40 atm. Undersizing by 0.5 mm was recommended for predilatation, followed by a 0.25 mm larger noncompliant balloon if needed. For postdilatation, a 1:1 balloon-to-stent ratio was advised in straight, nontortuous segments.
In a systematic review and meta-analysis of 1,015 patients (93.7% moderate or heavily calcified and 40.4% in-stent) treated with OPN balloon, procedural success rate was 95.1% (95% CI 89.3 to 98.8%). The incidence of periprocedural MACE and coronary perforation was 1.9% and 0.6%, respectively.
In a bench study, 17 calcified coronary lesions from 6 cadavers were randomized to intravascular lithotripsy (IVL, n = 5), cutting balloon (CB, n = 6), or ultra–high-pressure balloon (UHB, n = 6). Pre and post-treatment optical coherence tomography (OCT), micro-computed tomography (micro-CT), and histology were coregistered to assess calcium fracture patterns and vascular injury. Although the overall frequency of calcium fractures was comparable among the 3 modalities, IVL was associated with significantly less medial injury; furthermore, when lesions were stratified by calcium arc (concentric vs eccentric), IVL produced a greater number of fractures.
The value of IVL Compared To OPN noncompliant balloons for treatment of RefractorY Coronary Lesions (VICTORY) trial (NCT05346068, presented at TCT 2025 by Dr. Matthias Bossard) randomized 278 patients to OPN versus IVL. Final stent expansion measured by OCT (primary outcome) was 85.0% with OPN versus 84.0% with IVL (median difference 1.0 [95% CI −2.45 to 4.45], p = 0.570 for superiority and p <0.0001 for noninferiority). Procedural (92.03% vs 86.13%, p = 0.149) and strategy (98.6% for both) success and safety profile were similar between OPN and IVL.
In summary, the OPN balloon has favorable safety and efficacy for treating undilatable and heavily calcified lesions with low incidence of major periprocedural complications, such as perforation (0.6 %, 95% CI 0.3 to 1.5%, I² 87.2%) and death (0% in all studies except one that reported 2.8% mortality, Table 2 ). There was variability in the incidence of complications across studies that likely reflects differences in lesion characteristics, imaging guidance, operator experience, and procedural technique, in addition to random variation given the overall low event rates.
Indications for Use
The OPN balloon can be used either as the initial treatment strategy or after failure of other strategies. It is also used for stent optimization after implantation.
In the Society of Cardiovascular Angiography and Intervention (SCAI) algorithm for managing calcified coronary lesions, intravascular imaging (intravascular ultrasound [IVUS]/OCT) should be used to assess calcium arc, length, and thickness. Advanced calcium modification is recommended for lesions with 360° arc or ≥270° arc with calcified length ≥5 mm. Additional indications include calcified nodules, calcium thickness ≥0.5 mm (as assessed by OCT), and small or negatively remodeled vessels. A more recent imaging-based score encourages lesion preparation in the presence of calcium arc >270° for a length >3 mm, calcium angle of 360° at a single cross-section, and minimum calcium thickness >0.3 mm. Atherectomy is preferred for long, diffuse calcification; specialty balloons for focal lesions; and IVL should be considered for concentric, eccentric, or nodular calcium, especially when atherectomy is contraindicated. Imaging can help confirm adequate modification before stent implantation.
For balloon or microcatheter uncrossable lesions, rotational or orbital atherectomy is usually used as the first strategy, followed by additional strategies, such as the OPN balloon if the lesion fails to expand with balloon dilatation ( Figure 2 ).
