Electrophysiological characteristics of septal hypertrophy in patients with hypertrophic obstructive cardiomyopathy and moderate to severe symptoms.

BACKGROUND: In hypertrophic obstructive cardiomyopathy, regional hypertrophy, myocardial replacement scarring, expanded interstitial fibrosis, and myocardial disarray can be found. The electrophysiological consequences of this substrate have not yet been investigated. Thus, the aim of this study was to assess the local electrophysiological characteristics of regional left ventricular (LV) septal hypertrophy. METHODS AND RESULTS: In 9 patients with hypertrophic obstructive cardiomyopathy, electroanatomic voltage mapping of the LV was performed during sinus rhythm to determine the regional voltage amplitude. In addition, the morphology of the regional bipolar endocardial electrogram was assessed. During multisite LV stimulation, the stimulus-to-V intervals in both septal hypertrophy and the lateral LV myocardium were determined. Bipolar electroanatomic voltage mapping revealed a significant reduction in regional voltage amplitude in septal hypertrophic areas compared with lateral LV areas without evidence of hypertrophy (0.41+/-0.24 versus 13.5+/-1.85 mV; P<0,001). Local bipolar electrogram analysis demonstrated fractionated and prolonged endocardial potentials in septal hypertrophic areas (with split potentials present in 6 patients) that were not revealed at lateral myocardial sites (110.1+/-24.6 versus 80.1+/-6.6 ms; P=0.005). The stimulus-to-V interval was significantly longer (62.9+/-10.3 versus 24.1+/-9.1 ms; P=0.005) in septal hypertrophic areas compared with the lateral LV. CONCLUSIONS: In LV regions with extensive hypertrophy, a marked reduction of bipolar voltage amplitude can be found, as well as local conduction delay and conduction block. This result is consistent with the findings of regional myocardial scarring and may contribute to the increased incidence of ventricular tachyarrhythmias in patients with hypertrophic obstructive cardiomyopathy.

[Interventional treatment in hypertrophic cardiomyopathy]. / Hypertrophische Kardiomyopathie Myektomie, Schrittmacher, TASH oder ICD?

Hypertrophic cardiomyopathy (HCM) is a genetic cardiac disease phenotypically expressed in the general population at about 0.2%. Annual mortality rate is about 1% in unselected patients, 3-6% in patients with severe symptoms, and 17% following resuscitation from ventricular tachycardia (VT)/ventricular fibrillation (VF). 50-80% of deaths are sudden. Beneath effective treatment in severe symptoms of heart failure (most common in midlife and beyond) the prevention of sudden death (most common in young patients) continues to be a major challenge. The highest risk has been associated with any of the following markers: 1. prior cardiac arrest or spontaneous sustained VTs, 2. a family history of premature HCM-related death, 3. extreme left ventricular hypertrophy (> or = 30 mm), 4. syncope, 5. multiple bursts of nonsustained VTs, 6. hypotensive blood pressure response to exercise, and 7. marked septal scarring (hyperenhancement in magnetic resonance imaging). Treatment options in patients with drug-refractory symptoms or increased risk of sudden death are surgical myectomy, transcoronary ablation of septal hypertrophy (TASH), dual-chamber pacing, ablation of atrial fibrillation (or the AV node), and the implantable cardioverter defibrillator (ICD). 1. Surgical myectomy effectively improves symptoms, hemodynamics and probably prognosis. Long-term results are well known, but patients' preference and the number of experienced surgical centers are fading. Randomized studies are missing. 2. TASH induces quite similar improvements in symptoms and hemodynamics. It is remarkably evaluated for a postprocedural follow-up of up to 10 years, and it is the preferred mode of treatment in patients. However, information on long-term prognosis, rhythmogenic effects and randomized studies are missing. For the prevention of sudden death, TASH has to be combined with an ICD. 3. Dual-chamber pacing was evaluated in randomized crossover studies, but symptomatic and hemodynamic improvements and patients' preference are substantially lower than for TASH. 4. The ICD has the potential to alter prognosis in secondary (class I indication) and primary prevention. HCM patients should undergo a risk stratification assessment. Prophylactic implants base on a clinical profile with two or more risk markers (sometimes one risk marker). 5. Ablation of atrial fibrillation or the AV node is indicated to improve symptoms in patients with fast ventricular rates despite medical treatment. For the prevention of sudden death, it has to be combined with an ICD.

Role of transcoronary ablation of septal hypertrophy in patients with hypertrophic cardiomyopathy, New York Heart Association functional class III or IV, and outflow obstruction only under provocable conditions.

BACKGROUND: Transcoronary ablation of septal hypertrophy (TASH) for hypertrophic cardiomyopathy seems to be an effective alternative to surgical myectomy. It remains a point of debate whether an outflow obstruction at rest is a necessary criterion for interventional therapy. METHODS AND RESULTS: TASH was compared in 45 consecutive patients with no resting gradient and a provocable gradient of > or =30 mm Hg (group I) and in 84 consecutive patients with a resting gradient of > or =30 mm Hg (80+/-33 mm Hg) (group II). At baseline, all patients were in NYHA functional class (FC) III or IV, unresponsive to medical treatment. Patients in group I were older (63+/-12 versus 55+/-17 years, P=0.005) and had a lower postextrasystolic gradient (110+/-44 versus 171+/-40 mm Hg, P<0.001). The groups were similar with respect to NYHA FC (3.1+/-0.3 versus 3.1+/-0.3), basal septal thickness (22+/-4 versus 23+/-3 mm), maximal oxygen consumption (13.1+/-4.6 versus 14.5+/-5.0 mL/kg per minute), and pulmonary artery mean pressure at workload (42+/-9 versus 42+/-10 mm Hg) (P>0.05). Median follow-up was 7 months after TASH. The 2 groups showed a significant and similar improvement in provocable obstruction (to 24+/-24 and 56+/-51 mm Hg, respectively), basal septal thickness (to 12+/-3 and 12+/-4 mm, respectively), NYHA FC (to 1.7+/-0.6 and 1.5+/-0.6, respectively), maximal oxygen consumption (to 16.0+/-5.3 and 16.6+/-6.0 mL/kg per minute, respectively), and pulmonary artery mean pressure at workload (to 36+/-9 and 34+/-9 mm Hg, respectively) (P>0.05). CONCLUSIONS: TASH seems to have beneficial clinical and hemodynamic effects in patients with either provocable or resting outflow obstruction.