Alcohol septal ablation for hypertrophic obstructive cardiomyopathy

Hypertrophic Obstructive Cardiomyopathy: Surgical Myectomy and Septal Ablation

Hypertrophic cardiomyopathy is a genetic disorder characterized by marked hypertrophy of the myocardium. It is frequently accompanied by dynamic left ventricular outflow tract obstruction and symptoms of dyspnea, angina, and syncope. The initial therapy for symptomatic patients with obstruction is medical therapy with β-blockers and calcium antagonists. However, there remain a subset of patients who have continued severe symptoms, which are unresponsive to medical therapy. These patients can be treated with septal reduction therapy, either surgical septal myectomy or alcohol septal ablation. When performed by experienced operators working in high-volume centers, septal myectomy is highly effective with a >90% relief of obstruction and improvement in symptoms. The perioperative mortality rate for isolated septal myectomy in most centers is <1%. Alcohol septal ablation is a less invasive treatment. In many patients, the hemodynamic and clinical results are comparable to that of septal myectomy. However, the results of alcohol septal ablation are dependent on the septal perforator artery supplying the area of the contact between the hypertrophied septum and the anterior leaflet of the mitral valve. There are some patients, particularly younger patients with severe hypertrophy, who do not uniformly experience complete relief of obstruction and symptoms. Both techniques of septal reduction therapy are highly operator dependent. The final decision as to which approach should be selected in any given patient is dependent up patient preference and the availability and experience of the operator and institution at which the patient is being treated.

A decade of percutaneous septal ablation in hypertrophic cardiomyopathy

Percutaneous septal ablation has emerged as a less invasive treatment of symptomatic patients with hypertrophic obstructive cardiomyopathy (HOCM). In the past decade, the availability of this sophisticated technique has revived the interest of cardiologists in left ventricular outflow tract obstruction, which led to the recognition that most patients with HCM have the obstructive type. Follow-up studies have already shown the safety and efficacy of the procedure, which offers symptomatic relief in most patients. Long-term survival is comparable to historical reports after surgical myectomy. Complications are rare and can be further reduced with increased experience of the operators, and the theoretical concern for possible ventricular arrhythmogenicity of the myocardial scar has not been documented by the existing data. Although there are still no randomized trials, percutaneous septal ablation is undeniably a viable alternative for patients with HOCM.

Severe symptoms in mid and apical hypertrophic cardiomyopathy

BACKGROUND

We analyzed the clinical and quantitative echocardiographic characteristics of patients with sub-basal hypertrophic cardiomyopathy (HCM) to define the characteristics of patients (pts) with severe symptoms.

METHODS

Of 444 pts in a referral-based HCM program, 22 (5%) had midventricular or apical HCM. Quality of life (QoL) questionnaire was administered as an independent confirmer of symptomatic state.

RESULTS

Ten pts were NYHA III and IV, and 12 pts were NYHA I and II; QoL scores (41 +/- 26 vs. 10 +/- 13, P = 0.001) confirmed a priori division of two groups based on NYHA classification. Pts with more severe symptoms were more likely female (70% vs. 25%, P = 0.001) with atrial fibrillation (40% vs. 0%, P = 0.02). They more frequently had midventricular HCM 60% versus 8% (P = 0.01) (mid-LV thickness 17 +/- 6 vs. 12 +/- 2 mm, P = 0.03) and had much smaller LV diastolic volumes 68 +/- 12 versus 102 +/- 22 ml (39 +/- 4 vs. 53 +/- 12 ml/m(2), P = 0.001). Septal E/E' was higher in the severely symptomatic pts (15 +/- 5 vs. 7 +/- 3, P = 0.001) indicating higher estimated LV filling pressure. Midobstruction with apical akinetic chamber was noted in 4/10 pts who developed refractory symptoms. Cardiac mortality was higher in the severely symptomatic patients, 4/10 who had midventricular HCM as compared to 0/12 in the mildly symptomatic apical HCM group (P = 0.03).

CONCLUSIONS

In subbasal HCM, pts with severe symptoms have midventricular hypertrophy, with encroachment of the LV cavity and consequent very small LV volumes that may be complicated by mid-LV obstruction. Pts with mid-LV hypertrophy are more symptomatic than those with apical HCM, are often refractory to therapy, and have higher mortality.

Conduction system abnormalities in patients with obstructive hypertrophic cardiomyopathy following septal reduction interventions

We observed the impact of percutaneous transluminal septal myocardial ablation (PTSMA) and myectomy on the conduction system in patients with obstructive hypertrophic cardiomyopathy (HC). Septal reduction intervention is capable of eliminating the left ventricular outflow tract obstruction in patients with obstructive HC; however, conduction system abnormalities are frequent consequences of these procedures. A standard 12-lead electrocardiogram and Doppler echocardiogram were obtained in 204 patients who underwent PTSMA (n = 70) or myectomy (n = 134) before and at average of 3 months after intervention. Of 146 patients who had normal conduction systems before intervention, the duration of the QRS complex was significantly prolonged from 98 +/- 15 to 130 +/- 25 ms (p <0.0001), with right bundle branch block (RBBB) developing in 62% patients after PTSMA, and from 100 +/- 13 to 154 +/- 20 ms (p <0.0001), with left bundle branch block (LBBB) developing in 93% patients after myectomy. No significant difference in the QRS duration was found in the remaining 58 patients who had preexisting conduction abnormalities after intervention. In 174 patients without a preexisting permanent pacemaker, a pacemaker was implanted in 22% versus 13% of patients who underwent PTSMA (overall and without preexisting conduction block, respectively) and 10% versus 2% of patients with myectomy. The duration of baseline QRS was an independent predictor for the requirement of a permanent pacemaker (p <0.0001). Thus, RBBB often develops after PTSMA and LBBB is very frequently produced by myectomy. A possible requirement of a permanent pacemaker should always be considered before intervention when patients have preexisting RBBB or LBBB.

Targeting percutaneous transluminal septal ablation for hypertrophic obstructive cardiomyopathy by intraprocedural echocardiographic monitoring

BACKGROUND

Percutaneous septal ablation has evolved as an alternative to surgery for reducing symptoms and outflow gradients in patients with hypertrophic obstructive cardiomyopathy. Intraprocedural echo-cardiographic imaging can improve clinical and hemodynamic results. Growing experience with this method has additionally shown that threatening necrosis of the myocardium distant from the septal target region can be detected.

METHODS AND RESULTS

Percutaneous septal ablation was performed in 162 patients (80 women, 82 men; aged 54.1 +/- 15.5 years); 131 of whom were targeted by intraprocedural myocardial contrast echocardiography. In 11 patients (7%), an atypical target vessel or a perfusion area distant from the expected septal target region was detected, leading to a target vessel change. Permanent pacing was necessary in 14 patients (9%). Three patients (2%) died. After 3 months, the mean New York Heart Association functional class was reduced in the returning 159 patients from 2.8 +/- 0.5 to 1.3 +/- 1.0 (P <.0001) along with a gradient reduction from 77 +/- 35 to 12 +/- 22 mm Hg at rest, and from 147 +/- 43 to 44 +/- 45 mm Hg with provocation (P < .0001 each). The main reason for unsatisfactory gradient reduction was suboptimal scar placement in the patients treated before the introduction of intraprocedural myocardial contrast echocardiography.

CONCLUSIONS

Percutaneous septal ablation is an effective nonsurgical technique for reducing symptoms and outflow gradients in hypertrophic obstructive cardio-myopathy. Echocardiographic guidance adds substantially to safety and efficacy of the procedure and should therefore be considered routinely.