IVL vs Non‑Compliant Balloon: Coronary Compliance and Practical Implications for Calcified PCI

The BENELUX‑IVL registry used a stepwise IVUS protocol to quantify how coronary artery compliance changes in balloon-crossable, heavily calcified lesions during calcified PCI—clarifying how much the vessel actually yields with escalating lesion preparation. In 28 lesions, CACom was measured in the same treated segment at baseline, after high-pressure non-compliant dilation, and after intravascular lithotripsy. Both high-pressure NC ballooning and IVL increased IVUS-derived compliance, and IVL delivered the larger incremental gain beyond pressure-based dilation alone. Clinically, a quantified compliance metric may help operators distinguish when pressure has produced meaningful mechanical change versus when adding IVL is more likely to provide safer plaque modification and more predictable stent expansion in the same case.

Severe coronary calcium remains a common driver of stent underexpansion: rigid plaque resists dilation, while higher inflation pressures can shift stress to less calcified segments and raise the risk of dissection or perforation. Coronary artery compliance (CACom) translates that mechanical problem into a measurable signal—change in lumen area per change in pressure—turning “balloon feel” into a reproducible intraprocedural readout of whether the target segment is becoming more distensible after each step. Used as a checkpoint, rising compliance suggests the lesion is yielding; a flat signal suggests persistent resistance despite pressure and device exchanges. That framing can complement angiography and balloon behavior when deciding whether to keep escalating pressure or move to a calcium-modifying adjunct during the same procedure.

The procedural frame was balloon-crossable, heavily calcified lesions, with core-lab IVUS standardizing measurements across the treated segment and enabling CACom calculations at baseline, after NC balloon inflation at ≥16 atm, and again after IVL pulse delivery. High-pressure NC dilation functioned as the routine pre‑IVL step, IVL was applied as an adjunct maneuver, and high-pressure post-dilation was frequently used after IVL to finalize lesion preparation and optimize geometry. Treatment parameters anchored the pathway: median maximum pre‑IVL NC balloon diameter was 3.0 mm at 18 atm; post‑IVL high-pressure dilation occurred in 85.7% of lesions; and median maximum post‑IVL balloon diameter was 4.0 mm at 18 atm. Immediate endpoints emphasized the mechanical effect (ΔCACom across steps), imaging correlates such as calcium fracture and stent expansion, and procedural success as a near-term safety and effectiveness snapshot.

The stepwise CACom signal separated pressure-based stretch from additional plaque-modifying gain: median CACom increased from 0.17 mm²/mmHg at baseline to 0.32 mm²/mmHg after high-pressure NC inflation and to 0.65 mm²/mmHg after IVL in this BENELUX‑IVL registry IVUS CACom analysis. In paired comparisons, incremental effects favored IVL over NC dilation (median NC effect 0.14 mm²/mmHg vs median IVL effect 0.23 mm²/mmHg; p=0.03), with interpretation appropriately limited to this 28-lesion cohort. In practical terms, NC ballooning produced measurable compliance gain, yet IVL added further compliance even in lesions that were already balloon-crossable. The pattern supports viewing IVL as a compliance-enhancing add-on when the post‑NC response remains incomplete on IVUS during the same sitting.

This report is centered on within-lesion, stepwise CACom changes and accompanying procedural/IVUS findings. It does not include a multivariable predictors model for larger ΔCACom, and the small, single-cohort design limits inferences about which lesion or vessel characteristics drive larger compliance gains.

IVUS still provided mechanistic correlates: macroscopic calcium fractures were observed in 75% of lesions, consistent with true plaque modification rather than elastic stretch alone. Stent expansion metrics were generally favorable for a heavily calcified setting, with mean minimal stent area 9.9 mm², mean stent expansion 81%, and stent expansion >80% achieved in 67.9% of lesions—linking the compliance signal to a procedural objective that can be confirmed on imaging. Pairing a compliance rise with imaging-visible fracture and acceptable expansion may offer a tighter confirmation loop that lesion preparation is adequate before concluding optimization attempts.

Sequencing in the cohort reflected a combination strategy: high-pressure NC dilation as the default first step and IVL as the complementary maneuver rather than a full substitute, preserving deliverability in balloon-crossable lesions while seeking additional compliance gain when needed. The pathway also sets clear boundaries for interpretation: upfront rotational or orbital atherectomy was excluded by design, so these compliance and expansion findings apply to a balloon-crossable, calcified pathway rather than an atherectomy-first approach. Short-term performance was summarized by a procedural success rate of 96.4%, defined by successful IVL delivery to the target lesion, absence of intraprocedural major adverse cardiac events, and final TIMI III flow; this is an immediate safety-and-effectiveness snapshot, not a longitudinal outcome claim. Taken together, CACom alongside IVUS fracture and expansion measures can function as a coherent intraprocedural feedback loop—helping standardize when to stop at high-pressure dilation and when to add IVL to reduce uncertainty around stent expansion as larger datasets mature.