Transcatheter Myotomy to Reduce Left Ventricular Outflow Obstruction

BACKGROUND

Left ventricular outflow tract (LVOT) obstruction is a source of morbidity in hypertrophic cardiomyopathy (HCM) and a life-threatening complication of transcatheter mitral valve replacement (TMVR) and transcatheter aortic valve replacement (TAVR). Available surgical and transcatheter approaches are limited by high surgical risk, unsuitable septal perforators, and heart block requiring permanent pacemakers.

OBJECTIVES

The authors report the initial experience of a novel transcatheter electrosurgical procedure developed to mimic surgical myotomy.

METHODS

We used septal scoring along midline endocardium (SESAME) to treat patients, on a compassionate basis, with symptomatic LVOT obstruction or to create space to facilitate TMVR or TAVR.

RESULTS

In this single-center retrospective study between 2021 and 2023, 76 patients underwent SESAME. In total, 11 (14%) had classic HCM, and the remainder underwent SESAME to facilitate TMVR or TAVR. All had technically successful SESAME myocardial laceration. Measures to predict post-TMVR LVOT significantly improved (neo-LVOT 42 mm2 [Q1-Q3: 7-117 mm2] to 170 mm2 [Q1-Q3: 95-265 mm2]; P < 0.001; skirt-neo-LVOT 169 mm2 [Q1-Q3: 153-193 mm2] to 214 mm2 [Q1-Q3: 180-262 mm2]; P < 0.001). Among patients with HCM, SESAME significantly decreased invasive LVOT gradients (resting: 54 mm Hg [Q1-Q3: 40-70 mm Hg] to 29 mm Hg [Q1-Q3: 12-36 mm Hg]; P = 0.023; provoked 146 mm Hg [Q1-Q3: 100-180 mm Hg] to 85 mm Hg [Q1-Q3: 40-120 mm Hg]; P = 0.076). A total of 74 (97.4%) survived the procedure. Five experienced 3 of 76 (3.9%) iatrogenic ventricular septal defects that did not require repair and 3 of 76 (3.9%) ventricular free wall perforations. Neither occurred in patients treated for HCM. Permanent pacemakers were required in 4 of 76 (5.3%), including 2 after concomitant TAVR. Lacerations were stable and did not propagate after SESAME (remaining septum: 5.9 ± 3.3 mm to 6.1 ± 3.2 mm; P = 0.8).

CONCLUSIONS

With further experience, SESAME may benefit patients requiring septal reduction therapy for obstructive hypertrophic cardiomyopathy as well as those with LVOT obstruction after heart valve replacement, and/or can help facilitate transcatheter valve implantation.

Acute Hemodynamic Compromise After Transcatheter Aortic Valve Replacement Due to Dynamic Left Ventricle Obstruction: A Systematic Review

Acute hemodynamic compromise after transcatheter aortic valve replacement (TAVR) because of dynamic left ventricle (LV) obstruction (LVO), also known as suicide LV, is an infrequent but severe complication of TAVR that is poorly defined in previous studies. Understanding this complication is essential for its prompt diagnosis and optimal treatment. We conducted a systematic literature review using PubMed, Embase, Web of Science, and Medline databases for studies describing acute hemodynamic compromise after TAVR because of dynamic LVO or suicide LV. Each study was reviewed by 2 authors individually for eligibility, and a third author resolved disagreements. From a total of 506 studies, 25 publications were considered for the final analysis. The majority of patients with this condition were women demonstrating a hypertrophic septum, a small ventricle, and hyperdynamic contractility on pre-TAVR echocardiographic assessment. An intraventricular gradient before TAVR was found in half of the cases. Acute hemodynamic compromise after TAVR because of dynamic LVO manifested mainly as significant hypotension and occurred most often immediately after valve deployment. The LV outflow tract was the most common site of obstruction. Advanced therapies were required in nearly 65% of the cases. In conclusion, acute hemodynamic compromise after TAVR because of dynamic LVO occurred almost invariably in women. Echocardiography before TAVR may offer essential information to anticipate this complication. LV outflow tract obstruction appears to carry the highest risk of developing this phenomenon. Advanced therapies should be promptly considered as a bailout strategy in patients with hemodynamic collapse refractory to medical therapy.

Conservative Management of Suicide Left Ventricle After Surgical Aortic Valve Replacement

Suicide left ventricle (SLV) remains an underdiagnosed cause of haemodynamic compromise following surgical or transcatheter aortic valve replacement (AVR). Risk factors include female sex and a small left ventricular cavity with asymmetric septal hypertrophy. We present the case of a 63-year-old woman, with a medical history of diabetes mellitus, arterial hypertension and dyslipidaemia who was diagnosed with severe aortic stenosis with normal left ventricular ejection fraction and concentric hypertrophy. She underwent surgical AVR using a bioprosthetic valve, but a few hours after surgery, she developed sudden cardiogenic shock. An urgent transthoracic echocardiogram was performed showing marked systolic anterior motion of the mitral valve resulting in severe dynamic left ventricular outflow tract obstruction and intraventricular gradient. The diagnosis of SLV was made. The patient was managed conservatively with volume loading and oral beta-blockers and her haemodynamic state improved gradually. She was then discharged after favourable evolution. Medical management of SLV includes volume loading to expand the ventricular volume and beta-blockers for their negative inotrope effect. When medical therapy fails, surgical myectomy or alcohol septal ablation can be proposed to remove the obstacle. Some authors have proposed these procedures as prophylactic measures to prevent SLV in high-risk patients.

Acute decompensated heart failure after transcatheter aortic valve implantation: A case report

Transcatheter aortic valve implantation (TVAI) is a widely used treatment modality for severe aortic stenosis. The complication rates of the procedure have gradually decreased over time, owing to the improvements in procedural skills and development of TVAI devices. However, several rare but serious complications can still occur after TAVI. We recently encountered acute decompensated heart failure as a rare and fatal complication of TAVI and would like to share our experience.