Disrupt CAD III: Safety and effectiveness of intravascular lithotripsy for treatment of severe coronary calcification

Reported from the TCT Congress 2020

The DISRUPT CAD III study was the US Pivotal study for coronary intravascular lithotripsy (IVL). This prospective, single arm, IDE study was performed in 47 sites in the US, UK, Germany and France to evaluate safety and effectiveness of IVL.

It included patients with a single heavily calcified de novo stenosis 50% with RVD 2.5 mm and 4.0 mm, and a total lesion length 40 mm.

The primary safety endpoint was freedom from major adverse cardiovascular events (MACE) at 30 days, defined as the composite of cardiac death, myocardial infarction (MI), or target vessel revascularization (TVR); whereas the primary effectiveness endpoint was successful stent delivery with residual stenosis < 50% and without in-hospital MACE. The performance goals were based on the single-arm ORBIT II IDE study (an orbital atherectomy study) with a relative risk of 1.5, and corresponded to 84.4% for the primary safety endpoint and 83.4% for the primary effectiveness endpoint.

After the roll-in phase (1 pt/center), 384 patients were included in the study. Lesions treated were mostly located in the LAD (56.5%), followed by the RCA (29.2%). Importantly, all treated lesions were deemed to have severe calcification by the core-lab analysis, and the extension of calcification was also impressive (49.9  18.8 mm). Mean procedure time was just short of 1h, suggesting that IVL does not significantly prolong the procedure.

Predilation before IVL was performed in 55%, and stent delivery was possible in 99.2% of the cases. The primary safety endpoint of freedom from 30-day MACE was observed in 92.2% of patients, exceeding the performance goal. Similarly, the primary effectiveness endpoint for procedural success occurred in 92.4%, exceeding the performance goal. Final in-stent diameter stenosis 30% was achieved in 99.5% of the patients, with an average post-stent DS of 11.9%.

No perforations occurred. Severe dissection (type D-F) was present in 8 patients (2.1%) after IVL, and in 1 patient after stenting.

At the 30-day follow-up, 2 patients had died: one for abrupt vessel closure after stent delivery failure, and the other for cardiogenic shock due to target vessel (non target-lesion) STEMI after discharge. MACE rate was 7.6%, driven mainly by periprocedural MI.

Transient ventricular capture or “shocktopics” were observed in around 40% of the patients, and despite a bigger drop in systolic BP during the procedure, were not associated with sustained ventricular arrhythmia nor with bad outcomes.

In conclusion, IVL exceeded expectations with regards to both safety and effectiveness. Its ease of use led to very few procedural complications and to very high procedural success, and IVL will soon likely be a valuable addition to US interventional cardiologists’ armamentarium to treat calcified lesions.

Intravascular lithotripsy and the algorithmic approach to calcified lesions

The main message of this study appears to be that when IVL is planned, successful delivery of the balloon over a calcified coronary lesion was achieved in almost all cases (98.2%), thus facilitating the delivery of a stent (99.2%) with in-stent residual stenosis <50% obtained in all cases and freedom from in-hospital MACE (including periprocedural MI) in 93%.
Moreover, an intracoronary imaging sub-study with OCT was able to confirm that optimal stent expansion was made possible by IVL independently of the OCT-documented calcium fractures (which were seen in 67% of patients). Together with a low rate of periprocedural complications including the absence of any coronary perforations, these results seem to attest to the favourable efficacy and safety profile of IVL in patients with calcified lesions.

However, given that the smallest available IVL balloon diameter was 2.5mm, and that the reported rate of pre-dilatation was only 55%, the enrolled patient population seems not to be entirely reflective of consecutive real-world patients with calcified coronary lesions. In an all-comer population with severely calcified lesions, it is conceivable that the IVL delivery may not be near 100% as here presented, and that other devices, such as atherectomy, would need to be used to facilitate IVL and/or stent delivery.
Therefore, a prospective controlled study evaluating the effects of IVL in the context of other available devices (e.g. rotational/orbital atherectomy and high-pressure/scoring/cutting balloons) may be needed to better inform the clinical practice on the complementarity of these techniques when treating calcified coronary lesions. 

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