Until recently, there was sparse evidence of the value of a novel technology called intravascular lithotripsy-facilitated percutaneous balloon mitral valvuloplasty (IVL-PBMV) for treating patients with severe calcific mitral stenosis (MS) with no other surgical or transcatheter treatment options.
There had been only isolated case reports from various centres.
The interventional cardiology and structural heart team at Henry Ford Health, Michigan, reported its first use of the technology in 2019 for an 81-year-old man with calcified mitral stenosis, a mean diastolic gradient of 11 mmHg, and New York Heart Association functional class III heart failure.
Although originally deemed "inoperable," after IVL-PBMV, the man recovered neurologically intact.
Since then, the team has been using the technology for similar difficult-to-treat patients.
They recently reported a case series of 24 patients with severe mitral annular calcification (MAC) and severe MS treated at Henry Ford between 2019 and 2023.
“This is an extremely challenging group of patients to treat, so any advancement or new option in our armamentarium is important,” Pedro Engel-Gonzalez, MD, senior staff physician, Interventional Cardiology and Structural Heart Interventions Centre for Structural Heart Disease at Henry Ford, told theheart.org | Medscape Cardiology.
‘Kissing’ Balloons
Traditional percutaneous mitral balloon valvuloplasty uses a large non-compliant balloon. The procedure is not usually performed in older patients with severe MS because of the risk of causing severe mitral valve (MV) regurgitation.
The upshot is these patients were often left untreated, Engel-Gonzalez said.
The new approach uses Shockwave balloons (Intravascular Shockwave Lithotripsy System/Shockwave Medical, Santa Clara, California), which are approved, using different catheters, for the treatment of calcified coronary and peripheral vascular arterial disease.
This off-label use of the technology aims to address calcification in mitral valve disease.
Adapted from urologic lithotripsy used in the treatment of kidney stones, the intravascular lithotripsy system employs a similar technology to break up calcium in the cardiovascular system by causing acoustic disruptions in the calcium it comes in contact with when inflated, Engel-Gonzalez said.
“We observed via intra-op transoesophageal echocardiogram that after this treatment of the calcium on the leaflets and commissures, there is better pliability, which very likely mitigates the risk of severe mitral regurgitation when we then stretch the valve with a more traditional non-compliant balloon.”
The balloons in the Shockwave system were intended for the peripheral vasculature and so are relatively small, he noted. Therefore, the interventional cardiologist needs to use the “kissing balloon” technique – placing two or more balloons together to achieve total contact with the valve walls.
In the case series, a single IVL balloon was used for only one patient; two balloons were used in five patients and three balloons in 18.
The team also uses a Sentinel device (Sentinel Cerebral Protection System, Boston Scientific) to protect the brain from any calcium or debris that might get dislodged during the valvuloplasty procedure, potentially causing an embolic stroke.
The system is essentially a basket-type filter that sits in the brachiocephalic and left carotid artery during the procedure.
The Sentinel system was used in 17 of the 24 reported cases, but because one patient in whom it was not used had a stroke due to calcium embolising to the brain, “we decided from that point on to use it for all patients undergoing IVL-PBMV”, Engel-Gonzalez said. Notably, the patient who had the stroke was treated by interventional radiologists, who were able to remove parts of the calcium emboli.
In the case series overall, IVL-PBMV seemed to be safe and did result in effective reduction in the mitral valve gradients.
However, outcomes varied. One patient had a residual MV mean gradient > 10 mm Hg, and seven had a mean gradient > 5 mm Hg (mild stenosis < 5 mm Hg). Complications also occurred.
One patient experienced worsening mitral regurgitation from baseline, and one had an intra-procedural major complication – a right ventricular perforation requiring urgent extracorporeal membrane oxygenation and surgical repair. In addition, one patient had a late pericardial effusion requiring pericardiocentesis. Two had simultaneous alcohol septal ablation and developed complete heart block, which required implantation of a permanent pacemaker.
As noted earlier, one in whom a Sentinel device was not used developed a periprocedural stroke. Before IVL-PBMV can be used more widely, larger prospective studies are needed to validate the single-centre, retrospective series, the authors said.
“The next step would be a mechanistic study to try to quantify as much as possible, via pre- and post-CT and echocardiographic assessment, how IVL treatment is modifying the MV calcium and pliability of the leaflets,” Engel-Gonzalez said.
“We would also like to collaborate with other centres that may be interested in performing this procedure to create a multi-centre registry to better characterise efficacy, durability, and safety.” In addition, he added, the team would like to collaborate with a device company to develop a dedicated IVL balloon for valvuloplasty procedures.
‘Appears promising’
“These data provide a proof of concept supporting the safety and effectiveness of this innovative procedure as a treatment for severe calcific MS in patients with very high or prohibitive surgical risk,” Hani Jneid, MD, a member of the Writing Committee for the 2020 AHA/ACC Guidelines for the Management of Patients with Valvular Heart Disease, told theheart.org | Medscape Cardiology.
“It is very unlikely that a randomised trial will ever be conducted to prospectively examine the efficacy of this technique,” said Jneid, who is chief, Division of Cardiovascular Medicine and medical director, Cardiovascular Service Line at the University of Texas Medical Branch.
“It is important to realise that this a small case series from a tertiary centre, and the results need to be confirmed by other centres and operators and in a larger number of patients.”
Like Engel-Gonzalez, he noted that “maintaining a prospective and detailed clinical registry to examine safety and effectiveness endpoints, including long-term haemodynamic and hard outcomes, is critically important to adequately examine and refine this innovative technique”.
Still, PBMV “appears promising and helped achieve an average reduction in transmitral valve gradient of > 5 mm Hg, which is clinically meaningful”, he added.
However, the long-term safety outcomes, including MR, stroke, and pericardial complications, will need to be examined, as well.
“I doubt it will have as a big a therapeutic role as transcatheter mitral valve replacement or valve-in-MAC,” Jneid noted. “I also see no role for this technology in patients with severe rheumatic MS, where PBMV has established safety and efficacy and has a Class I indication by ACC/AHA guidelines.
“Using PBMV off-label by experienced operators in comprehensive valve centres and in select patients is reasonable, as long as it is considered in a shared-decision making model with the patient and after deliberations about the risks, benefits, and alternatives to this therapy.”
Medscape article – Lithotripsy for Mitral Valve Stenosis: What's the Promise? (Open access)
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