Effective treatment of hypertrophic cardiomyopathy with left ventricular outflow tract obstruction using a covered stent

Abstract

A woman in her 60s presented with progressive exertional dyspnoea, exertional chest pressure and exertional dizziness. Echocardiogram identified a 156 mm Hg left ventricular outflow tract gradient with provocation, indicating hypertrophic cardiomyopathy with left ventricular outflow obstruction—confirmed with MRI and angiogram. An alcohol septal ablation was planned but due to communication of the second septal perforator with the right ventricle and a wire-induced mid-left anterior descending artery dissection, alcohol septal ablation was not performed. Instead, a covered stent was placed in the mid-left anterior descending artery covering the origins of the third and fourth septal perforators. The left ventricular outflow tract gradient decreased from 90 to 30 mm Hg with provocation and her symptoms improved. Follow-up showed a left ventricular outflow tract gradient of 35 mm Hg with provocation and decreased symptoms.

Background

Hypertrophic cardiomyopathy is a common cardiovascular disorder which is found globally and can affect either sex, various races/ethnicities and all ages.¹ Hypertrophic cardiomyopathy commonly results in atrial fibrillation, arrhythmic sudden death and heart failure.¹ It is mainly characterised by asymmetric left ventricular hypertrophy with subaortic obstruction due to mitral valve systolic anterior motion with septal contact which leads to the disruption of laminar flow through the left ventricular outflow tract.² This obstruction leads to left ventricle systolic pressure overload with secondary mitral regurgitation and preserved/increased left ventricle function.

The diagnosis is made clinically with echocardiographic or MRI displaying a hypertrophied, non-dilated left ventricle in the absence of secondary causes.³ Mild-to-severe functional impairment seen in many hypertrophic cardiomyopathy patients manifests with exertional dyspnoea and fatigue.² There are medical, surgical (myectomy, cardioverter-defibrillators and transplantation) and percutaneous (alcohol septal ablation) interventions available. Pharmacological therapy (beta blockers and calcium channel blockers) is first line as they improve obstructive symptoms by decreasing the heart rate and prolonging diastolic fill time, elevating their quality of life.⁴ Septal myectomy and alcohol septal ablation are available for severe cases with the goal of decreasing the left ventricular outflow tract obstruction gradient and restoring proper flow.^4–6 There have also been a small number of cases using covered stents to occlude septal perforators—due to collateralisation, there has been mixed long-term results.^7–10

Case presentation

A woman in her 60s was evaluated following an abnormal echocardiogram, indicating hypertrophic cardiomyopathy with left ventricular outflow tract obstruction. Symptoms were progressively worsening for 6–18 months and included severe exertional dyspnoea, exertional chest pressure, exertional dizziness and resting dizziness, which worsened while dehydrated. History of cerebrovascular accident, hypertension and hyperlipidaemia. No family cardiac history including no sudden death. Brief smoking history 35 years ago. Medication included 100 mg/day metoprolol. Physical examination showed a body mass index (BMI) of 34.39 kg/m² BMI and a 2/6 aortic area systolic murmur, which increased to 3/6 with Valsalva and standing.

The original echocardiogram (figure 1) showed ejection fraction of 70%–75%, hypertrophic cardiomyopathy with dynamic subaortic stenosis and left ventricular outflow tract obstruction (156 mm Hg gradient with provocation) and moderate-to-severe mitral regurgitation. Cardiac MRI (figure 2) displayed a severe ostial tract obstruction (130 mm Hg gradient with provocation) and moderate-to-severe mitral regurgitation with systolic anterior motion. Myectomy or alcohol septal ablation were offered. Investigatory coronary angiogram found mild-to-moderate non-obstructive coronary artery disease involving the right coronary artery and a significant subaortic outflow tract gradient of >100 mm Hg with spike and dome pattern—alcohol septal ablation was planned.

Figure 1.

Echocardiograms prestent placement (top) and poststent placement (bottom). Take note of the y-axis unit change.

Figure 2.

Cardiac MRI showing a hypertrophic basal interventricular septum and systolic anterior motion of the mitral valve.

Right ulnar access was obtained for pigtail catheter to measure left ventricle pressure and right femoral access was obtained for intervention. A 0.14 coronary wire was placed into the second septal perforator. A 2.0 balloon occluded the second septal perforator’s origin and dye was injected distally. There was no extravasation or backflow in the left anterior descending; however, dye was seen within the right ventricle—confirmed echocardiographically with the presence of Definity contrast agent in the right ventricle (figure 3). Wiring of the third and fourth septal perforators was then attempted. During which, a flow-limiting dissection of the mid-left anterior descending was identified. Due to these procedural findings, the alcohol septal ablation was not performed. Instead, a Papyrus 3.5 × 20 mm covered stent was placed at the origins of the third and fourth septal perforators overlapping distally with a Xience 2.75 × 12 mm drug-eluted stent (figure 4). This resulted in thrombolysis in myocardial Infarction (TIMI) 3 flow and improvement of the left ventricular outflow tract gradient from 90 to 30 mm Hg with provocation, measured intraoperatively. On follow-up evaluation, her symptoms had drastically decreased and an echocardiogram showed a significantly improved left ventricular outflow tract gradient of 35–49 mm Hg with provocation (original echocardiogram showed 156–158 mm Hg; figure 1). Her decreased symptoms are stable 2 months postprocedure.

Figure 3.

Cardiac Catheterization image and simultaneousechocardiogram showing Definity contrast agent in the right ventricle when injected into the second septal perforator. Pig tail in left ventricle. A 2.25 × 12 balloon occluding the second septal perforator.

Figure 4.

Cardiac catheterization. (Top) Left anterior descending artery with septal perforators prestent placement. (Bottom) Left anterior descending artery with septal perforators poststent placement—no flow in third or fourth septal perforators.

Follow-up

One day postoperation, the left ventricular outflow tract gradient was 35 mm Hg and their symptoms were significantly decreased. Two months postoperation, their symptoms remained decreased.

Discussion

The present case used a covered stent since the original plan of alcohol septal ablation was abandoned due to mid-left anterior descending dissection and communication of the second septal perforator with the right ventricle. Stent placement over the origins of the third and fourth septal perforators resulted in a significantly decreased left ventricular outflow tract obstruction gradient as well as improved symptoms. While this is an atypical approach, it has been used previously.^7–10

The first successful case of treating hypertrophic cardiomyopathy with a covered stent was published in 1999. A covered stent was used to cover the origins of three septal perforators since balloon occlusion of each perforator individually only led to a partial gradient decrease. The intervention led to a ‘complete reduction’ in the gradient and after 4 months, the patient remained asymptomatic.¹⁰ In 2003, an alcohol septal ablation was unable to be performed due to the branch angle of the first septal perforator so a stent was placed occluding the origin. This resulted in 6 asymptomatic months with a decreased gradient (21 mm Hg) before collateralisation from the right coronary artery resulted in recurrence of symptoms and gradient (97 mm Hg); myectomy was then performed.⁷ In 2004, a covered stent was used due to the inability to cannulate the first septal artery; collateralisation from the right coronary artery led to symptom recurrence after an undisclosed period of time.⁸ Finally, in 2006, a woman with coronary artery disease and an alcohol septal ablation 6 months prior had a covered stent placed after symptom recurrence due to 70% stenosis of the left anterior descending and D1. Twelve months after placement, her gradient remained low and she was asymptomatic.⁹ These cases display the varying reasons for covered stent placement to treat hypertrophic cardiomyopathy along with their results over a relatively short follow-up period.

Our patient remains improved 2 months postprocedure, which is consistent with previous cases. However, two of the four previous cases ultimately resulted in symptom recurrence due to collateralisation and the two that did not either had a previous alcohol septal ablation performed or was only 4 months postprocedure. With that said, since alcohol septal ablation was contraindicated due to the risk of leaking through the dissection or ablating a portion of the right ventricle through the communication, the covered stent was a satisfactory backup for this unique patient. Additionally, with the limited data available, it seems that treating hypertrophic cardiomyopathy by occluding the origins of septal perforators with a covered stent provides short-term symptom relief and a reduced gradient. Nevertheless, long-term results are uncertain at this point and more data is needed to draw further conclusions.

Learning points.

• To understand how using a covered stent to treat hypertrophic cardiomyopathy with left ventricular outflow tract obstruction can be considered in cases where alcohol septal ablation is either difficult or contraindicated.

• To recognise that while this case shows short-term efficacy, long-term conclusions should not be drawn due to varying results with previous case reports and no long-term follow-up.

• To acknowledge that more scientific data must validate this approach before it is routinely considered concomitantly with alcohol septal ablation or myectomy.

Ethics statements

Patient consent for publication

Consent obtained directly from patient(s).