A sirolimus balloon for coronary ISR: what the US approval means

Why it matters

Coronary in-stent restenosis (ISR) creates an awkward interventional problem: the vessel has already received a permanent implant, yet recurrent tissue growth has narrowed the treated segment again. On 21 September, Cordis announced that the US Food and Drug Administration had approved its SELUTION SLR sirolimus drug-eluting balloon for coronary ISR. The development adds a “leave nothing behind” option to the US market, but the pivotal evidence needs more careful reading than the approval headline alone suggests. ^[1]

For cath-lab teams, the practical question is not whether balloons can deliver antiproliferative therapy. It is where this particular device fits alongside repeat drug-eluting stenting, plain balloon angioplasty and other lesion-specific strategies. For procurement teams, approval in one jurisdiction is also separate from local registration, reimbursement, training, stock support and total procedural cost.

What happened

Cordis says SELUTION SLR is now FDA approved for the treatment of coronary ISR and describes it as the first sirolimus drug-eluting balloon available in the United States. The company’s announcement links the decision to SELUTION4ISR, an international randomised trial conducted at 48 centres. ^{[1] [2] [3]}

The announcement is a US regulatory milestone. It does not establish SAHPRA registration, South African availability, medical-scheme reimbursement or an Aperture Science distribution relationship. None is asserted here. It also does not expand the evidence to de novo coronary lesions: Cordis reports that a separate US study in small de novo vessels has completed enrolment, but that programme is not the basis of the ISR conclusion discussed below. ^[1]

The data

SELUTION4ISR enrolled 418 patients after successful lesion preparation and randomised 210 to the sirolimus drug-eluting balloon and 208 to a usual-care control selected before randomisation. The control strategy contained approximately 80% repeat drug-eluting stenting and 20% plain balloon angioplasty. The primary endpoint was target lesion failure at 12 months—a composite of cardiac death, target-vessel myocardial infarction or clinically driven target-lesion revascularisation. ^{[2] [3]}

The primary per-protocol analysis included 390 patients. Target lesion failure occurred in 32 of 197 patients treated with the study balloon (16.2%) and 28 of 193 control patients (14.5%). The difference was 1.7 percentage points, with a 95% credible interval from −5.5 to 8.9 percentage points and a 98.80% posterior probability of non-inferiority. This met the prespecified criterion because the upper credible-interval boundary remained below the 10-percentage-point margin. ^[2]

The intention-to-treat analysis was consistent: target lesion failure occurred in 15.2% of the balloon group and 13.5% of the control group, a difference of 1.8 percentage points (95% credible interval −5.0 to 8.5) with a 99.18% posterior probability of non-inferiority. ^[2]

Interpreting the comparator

The important caution comes from the prespecified sequential comparison in patients with single-layer ISR. Target lesion failure occurred in 14.2% with the study balloon and 6.5% with repeat DES. The 7.7-percentage-point difference had a 95% credible interval from 0.6 to 14.6, and the 76.07% posterior probability did not satisfy the trial’s non-inferiority criterion. The authors therefore concluded that the balloon was non-inferior to the mixed usual-care strategy, but not non-inferior to DES in that single-layer comparison. ^[2]

“Not noninferior to DES for single-layer ISR for TLF at 12 months.” — Cutlip and colleagues. ^[2]

These results do not mean the balloon is inferior for every ISR presentation, nor do they prove equivalence to repeat DES. They show that the answer depends materially on the comparator and lesion context.

Mechanism in brief

Drug-eluting balloons combine angioplasty with short-term transfer of an antiproliferative agent to the vessel wall. SELUTION SLR uses sirolimus contained in biodegradable polymer micro-reservoirs that Cordis says are designed for sustained release for up to 90 days. The balloon is removed after inflation, so no additional permanent metal scaffold remains. ^[1]

That concept is attractive when another stent layer may be undesirable, but it does not remove the need for meticulous lesion preparation, assessment of the mechanism of restenosis and an acceptable angiographic result. A device-level mechanism should not substitute for intravascular imaging or clinical judgement where those are indicated.

Implications for South African professional practice

The approval should prompt evidence review, not automatic pathway change. Heart teams considering any coronary drug-eluting balloon need to define eligible ISR patterns, imaging expectations, lesion-preparation standards, bailout-stenting criteria and antiplatelet protocols within their own governance structures. The mixed control in SELUTION4ISR is especially relevant: comparing a new balloon with a pooled strategy is not the same question as comparing it directly with the best repeat-DES option for a specific lesion.

Procurement review should separate clinical evidence from market access. Teams would need verified SAHPRA status and approved indications, local instructions for use, compatible balloon sizes, training, pharmacovigilance arrangements, supply continuity and cost per completed case. US approval alone answers none of those local questions.

What to watch next

Longer follow-up will matter because ISR is a recurrent disease process and 12 months may not capture the full durability of either strategy. Further analyses should clarify outcomes by ISR mechanism, number of existing metal layers, vessel size, diabetes, imaging use and lesion complexity. Direct randomised comparisons against contemporary DES in clinically coherent subgroups would be particularly informative.

The separate de novo coronary programme should be read independently when results become available. Evidence for ISR cannot be carried across to small-vessel or broader de novo disease without its own endpoints, comparator and regulatory assessment.