Antiarrhythmic Drug Cibenzoline Attenuates Left Ventricular Pressure Gradient and Improves Transmitral Doppler Flow Pattern in Patients With Hypertrophic Obstructive Cardiomyopathy Caused by Midventricular Obstruction

Abstract

here are 2 types of hypertrophic obstructive cardiomyopathy (HOCM): obstruction at the subaorta, called idiopathic hypertrophic subaortic stenosis (IHSS), 1 and obstruction at the mid left ventricle. 2 In contrast to the many studies of IHSS, only a few studies, other than case reports, have focused on midventricular obstruction (MVO). Two patients with MVO were reported for the first time in 1976 by Falicov et al, 2 one of whom suddenly died shortly after unsuccessful myectomy. Maron et al elucidated that the left ventricular pressure gradient (LVPG) was related to even prognosis in patients with hypertrophic cardiomyopathy (HCM). 3 Thus, attenuation of the LVPG has recently become an important strategy in the management of patients with HOCM.In the clinical setting, patients with MVO may often be overlooked. Very recently we reported that there are 2 specific patterns of carotid pulse tracing in these patients, 4 by which they may be diagnosed with ease. As to the treatment of patients with MVO, Hintringer et al reported the usefulness of permanent DDD pacing to alleviate LVPG and symptoms in an 85-year-old woman with MVO who did not respond to pharmacological therapy. 5 In patients with MVO, unlike those with IHSS, therapies involving myotomy or myectomy and alcohol septal ablation require great caution to prevent the induction or deterioration of mitral regurgitation. Both -blockers and calcium antagonists are often insufficient for attenuating LVPG. In 1982, Pollick reported the usefulness of the antiarrhythmic drug disopyramide in attenuating LVPG in IHSS. 6 Unfortunately sustained use of disopyramide is difficult owing to the thirst, dysuria and so on related to its strong anticholinergic action. We previously reported the usefulness of the antiarrhythmic drug, cibenzoline, the anticholinergic action of which is very weak, 7 to attenuate LVPG in IHSS. 8 In the present study, therefore, we examined the acute and chronic effect of cibenzoline on LVPG and left ventricular (LV) diastolic dysfunction in patients with MVO. Methods Study SubjectsTwenty-three patients with MVO participated in this study after giving written informed consent. Twenty healthy control subjects served as the comparison of the hemo-

Effect of Intravenous Administration of Cibenzoline on Left Ventricular Diastolic Pressures in Patients With Hypertrophic Cardiomyopathy Its Relationship to Transmitral Doppler Flow Profiles

“…5 The other class Ia antiarrhythmic drug, cibenzoline, can also attenuate the LVPG. 7,8 In the present study, we have for the first time administered cibenzoline intravenously to patients with HNCM and the effects on LV diastolic pressure were similar to those in patients with HOCM. A strong sodium-channel blocking action, which is common to disopyramide and cibenzoline, may be closely related to the attenuation of LVPG in patients with HOCM.…”

“…The suggested mechanism was the negative inotropic action of disopyramide and an indirect effect associated with reduction of the LVPG and mitral regurgitation. 5 Another class Ia antiarrhythmic drug, cibenzoline, has attenuated the LVPG in patients with HOCM, 7,8 as well as improving left ventricular (LV) diastolic dysfunction in both patients with HOCM 7 and hypertrophic nonobstructive cardiomyopathy (HNCM). 9 We interpret that this beneficial effect of cibenzoline might be caused by a decrease in both the left atrial and LV diastolic pressures, 7,9,10 but there are contradictory opinions about this.…”

QRS Prolongation is Associated With High Defibrillation Thresholds During Cardioverter-Defibrillator Implantations in Patients With Hypertrophic Cardiomyopathy

“…Furthermore, class Ia antiarrhythmic drugs such as disopyramide or cibenzoline might lead to a rise in DFT by producing a wider zone between the resting membrane potential and threshold potential. 13 However, class Ia antiarrhythmic agents have been regarded as part of the standardized therapy, not only for reducing LV pressure gradients [5][6][7] in patients with obstructive HCM, but also for improving LV diastolic dysfunction even in patients with non-obstructive HCM. 14,15 Therefore, it is even more important to predict an increase in DFT before ICD implantation in patients with HCM.…”

“…Furthermore, class I agents are also used in HCM patients to control atrial fibrillation or reduce the pressure gradient in the left ventricular (LV) outflow tract or midventricle when an obstruction is present. [5][6][7] The combined use of antiarrhythmic agents and an ICD in patients with HCM, and the larger volume of myocardium (caused by hypertrophy of the left ventricle) might result in a high defibrillation threshold (DFT). However, the predictors of a high DFT in patients with HCM have not been fully characterized.…”

A985G Polymorphism of the Endothelin-2 Gene and Atrial Fibrillation in Patients With Hypertrophic Cardiomyopathy

“…In our series, 19 (17%) patients were taking class Ia antiarrhythmic agents at the time of the first clinical evaluation, despite the fact that no evidence of AF had been documented in any patient. Class Ia antiarrhythmic agents are now regarded as standard therapy, not only for reducing the LV pressure gradient in patients with obstructive HCM, [37][38][39] but also for improving LV diastolic dysfunction, even in patients with non-obstructive HCM. 40 sodes of tachyarrhythmia are sometimes prescribed these drugs.…”