Class Ia antiarrhythmic drug cibenzoline: a new approach to the medical treatment of hypertrophic obstructive cardiomyopathy

A Case of New-Onset Atrial Tachyarrhythmias With Apical Hypertrophic Cardiomyopathy and Bronchiectasis in a Very Elderly Patient: A Therapeutic Dilemma

Hypertrophic cardiomyopathy (HCM) is a primary myocardial disease that is genetically transmitted as an autosomal dominant trait. Even apical HCM (ApHCM) induces atrial fibrillation (AF) based on underlying left ventricle (LV) diastolic dysfunction, where anticoagulation therapy is recommended. However, anticoagulation for AF in patients at high risk of bleeding is a double-edged sword. A 98-year-old woman living in a nursing home presented to our hospital with sudden-onset dyspnea and palpitation persisting for two hours. The patient had a history of apical HCM and bronchiectasis. An electrocardiogram showed a regular tachycardia with a heart rate of 130 bpm, suggesting atrial flutter with 2:1 atrioventricular conduction. Intravenous verapamil (5 mg) resulted in the conversion into AF, and subsequent cibenzoline (70 mg) failed to restore sinus rhythm. Given the impossibility of continuous anticoagulation, electrical cardioversion was planned. Electrical cardioversion was successful in converting AF into sinus rhythm. Given the very high risk of hemoptysis, anticoagulation was avoided. This case gives an insight into how to manage a practical therapeutic problem, which is the coexistence of AF and bronchiectasis. A variety of individual factors should be considered for clinical decision-making and management of patients with concomitant HCM and AF.

Revisiting Diagnosis and Treatment of Hypertrophic Cardiomyopathy: Current Practice and Novel Perspectives

Sarcomeric hypertrophic cardiomyopathy (HCM) is a prevalent genetic disorder characterised by left ventricular hypertrophy, myocardial disarray, and an increased risk of heart failure and sudden cardiac death. Despite advances in understanding its pathophysiology, treatment options for HCM remain limited. This narrative review aims to provide a comprehensive overview of current clinical practice and explore emerging therapeutic strategies for sarcomeric HCM, with a focus on cardiac myosin inhibitors. We first discuss the conventional management of HCM, including lifestyle modifications, pharmacological therapies, and invasive interventions, emphasizing their limitations and challenges. Next, we highlight recent advances in molecular genetics and their potential applications in refining HCM diagnosis, risk stratification, and treatment. We delve into emerging therapies, such as gene editing, RNA-based therapies, targeted small molecules, and cardiac myosin modulators like mavacamten and aficamten, which hold promise in modulating the underlying molecular mechanisms of HCM. Mavacamten and aficamten, selective modulators of cardiac myosin, have demonstrated encouraging results in clinical trials by reducing left ventricular outflow tract obstruction and improving symptoms in patients with obstructive HCM. We discuss their mechanisms of action, clinical trial outcomes, and potential implications for the future of HCM management. Furthermore, we examine the role of precision medicine in HCM management, exploring how individualised treatment strategies, including exercise prescription as part of the management plan, may optimise patient outcomes. Finally, we underscore the importance of multidisciplinary care and patient-centred approaches to address the complex needs of HCM patients. This review also aims to encourage further research and collaboration in the field of HCM, promoting the development of novel and more effective therapeutic strategies, such as cardiac myosin modulators, to hopefully improve the quality of life and outcome of patients with sarcomeric HCM.

Current and emerging pharmacotherapy for the management of hypertrophic cardiomyopathy

INTRODUCTION

Hypertrophic cardiomyopathy (HCM) is one of the most common genetic causes of heart disease. Since the initial description of HCM, there have been minimal strides in management options. Obstructive HCM constitutes a larger subset of patients with increased left ventricular outflow tract gradients causing symptoms. Septal reduction therapy (SRT) has been successful, but it is not the answer for all patients and is not disease modifying.

AREAS COVERED

Current guideline recommendations include beta-blockers, calcium channel blockers, or disopyramides for medical management, but there lacks evidence of much benefit with these drugs. In recent years, there has been the emergence of cardiac myosin inhibitors (CMI) which have demonstrated positive results in patients with both obstructive and non-obstructive HCM. In addition to CMIs, other drugs have been investigated as we have learned more about HCM's pathological mechanisms. Drugs targeting sodium channels and myocardial energetics, as well as repurposed drugs that have demonstrated positive remodeling are being investigated as potential therapeutic targets. Gene therapy is being explored with vast potential for the treatment of HCM.

EXPERT OPINION

The armamentarium of therapeutic options for HCM is continuously increasing with the emergence of CMIs as mainstays of treatment. The future of HCM treatment is promising.

Efficacy of cibenzoline for hypertrophic obstructive cardiomyopathy in paediatric patients with RAS/MAPK pathway syndromes

RASopathies - caused by mutations in the RAS/MAPK signaling pathway - are frequently associated with cardiac diseases, such as hypertrophic obstructive cardiomyopathy. Although cibenzoline is useful for adult hypertrophic obstructive cardiomyopathy patients, little is known about its effect in children. Here, we report two paediatric cases of hypertrophic obstructive cardiomyopathy associated with RASopathies where the condition was improved by cibenzoline.

Valvulo-Arterial Impedance and Dimensionless Index for Risk Stratifying Patients With Severe Aortic Stenosis

The hemodynamic effects of aortic stenosis (AS) consist of increased left ventricular (LV) afterload, reduced myocardial compliance, and increased myocardial workload. The LV in AS patients faces a double load: valvular and arterial loads. As such, the presence of symptoms and occurrence of adverse events in AS should better correlate with calculating the global burden faced by the LV in addition to the transvalvular gradient and aortic valve area (AVA). The valvulo-arterial impedance (Zva) is a useful parameter providing an estimate of the global LV hemodynamic load that results from the summation of the valvular and vascular loads. In addition to calculating the global LV afterload, it is paramount to estimate the stenosis severity accurately. In clinical practice, the management of low-flow low-gradient (LF-LG) severe AS with preserved LV ejection fraction requires careful confirmation of stenosis severity. In addition to the Zva, the dimensionless index (DI) is a very useful parameter to express the size of the effective valvular area as a proportion of the cross-section area of the left ventricular outlet tract velocity-time integral (LVOT-VTI) to that of the aortic valve jet (dimensionless velocity ratio). The DI is calculated by a ratio of the sub-valvular velocity obtained by pulsed-wave Doppler (LVOT-VTI) divided by the maximum velocity obtained by continuous-wave Doppler across the aortic valve (AV-VTI). In contrast to AVA measurement, the DI does not require the calculation of LVOT cross-sectional area, a major cause of erroneous assessment and underestimation of AVA. Hence, among patients with LG severe AS and preserved LV ejection fraction, calculation of DI in routine echocardiographic practice may be useful to identify a subgroup of patients at higher risk of mortality who may derive benefit from aortic valve replacement. This article aims to elucidate the Zva and DI in different clinical situations, correlate with the standard indexes of AS severity, LV geometry, and function, and thus prove to improve risk stratification and clinical decision making in patients with severe AS.

Impact of cibenzoline treatment on left ventricular remodelling and prognosis in hypertrophic obstructive cardiomyopathy

Aims

This study aimed to elucidate the long‐term effect of cibenzoline therapy on cardiovascular complications and prognosis in patients with hypertrophic obstructive cardiomyopathy (HOCM).

Methods and results

Eighty‐eight patients with HOCM were treated with cibenzoline (Group A), and 41 patients did not receive cibenzoline (Group B). The changes in left ventricular (LV) remodelling, incidences of cardiovascular complications and deaths, were examined. The mean follow‐up period was 15.8 ± 5.6 years in Group A and 17.8 ± 7.2 years in Group B. In Group A, the LV pressure gradient (LVPG) decreased immediately after treatment, and the reduction was maintained throughout the study. In Group B, the LVPG decreased gradually according to the deterioration of LV function. LV reverse remodelling was confirmed in Group A, and LV remodelling advanced in Group B. In Group A, the incidence of each cardiovascular complication was <10%. Only one patient experienced LV heart failure (LVHF). LVHF incidence and atrial fibrillation were higher in Group B than those in Group A (P < 0.0001). The incidence of death was 20.5% in Group A and 90.2% in Group B (P < 0.0001). The most frequent cause of death was sudden cardiac death (SCD) (38.9%) in Group A and LVHF (67.6%) in Group B. The incidence of SCD showed no significant difference between the two groups. The cumulative cardiac survival rate was higher in Group A than that in Group B (P < 0.0001).

Conclusions

Cibenzoline treatment significantly reduced all cardiovascular complications and death due to LVHF and may be a promising treatment in patients with HOCM.

Predicting the clinical course in hypertrophic cardiomyopathy using thallium-201 myocardial scintigraphy

Aims

This study aimed to evaluate the changes in left ventricular remodelling with time in patients with hypertrophic cardiomyopathy (HCM) using thallium‐201 myocardial scintigraphy.

Methods and results

Forty‐eight patients with HCM participated in the study. The extent score (ES) and a newly devised index termed the ‘mean count change’ (MCC) were used to evaluate the myocardial perfusion defects. Using the amount of thallium‐201 uptake (TU), MCC (%) was calculated using the following formula: (last TU − initial TU)∕initial TU × 100. To confirm the site of the lesion, the left ventricle was divided into five segments: anterior, septal, inferior, lateral, and apex. Cardiovascular complications and deaths were recorded. The mean follow‐up period was 8.6 ± 2.0 years. ES increased from 17.4 ± 13.7% to 44.0 ± 22.3% (P < 0.0001). MCC increased from 0% to 12.0 ± 9.0% (P < 0.0001). The apex was the most frequent site of lesion. Twenty‐seven patients (56.3%) had experienced left ventricular heart failure (LVHF). Both ES and MCC were greater in patients with LVHF than in those without LVHF. An overlap between the two groups was greater in ES than in MCC. Patients with LVHF had a higher incidence of atrial fibrillation and apoplexy. Nineteen patients (39.6%) died during the study period; 14 died from LVHF, 3 from sudden cardiac death, and 2 from cancer.

Conclusions

Thallium‐201 myocardial scintigraphy is useful for detecting the severity of myocardial damage and for confirming the lesion site in patients with HCM. MCC may be superior to ES in the evaluation of these changes with time.

Chemical mapping as a predictor of vein of Marshall ethanol ablative effects

PURPOSE

The aim of this study was to test regional pharmacological effects of an antiarrhythmic agents to predict ablative effects.

BACKGROUND

The vein of Marshall (VOM) providing vascular access to myocardial tissue has been used for ablative purposes using ethanol.

METHODS

A total of 35 patients (male 21, 63.2 ± 7.8 years old) were included. A balloon-tipped infusion catheter was inserted into the VOM. Endocardial ultrahigh-resolution mapping was performed along the VOM region to record the change in atrial electrograms (AEs) after VOM injection of cibenzoline of 3.5 mg during sustained atrial fibrillation (AF). Subsequently, ethanol was infused into the VOM and ablative region was mapped.

RESULTS

In 17 patients (49 %), cibenzoline reduced AEs amplitude by >50%, all of which had also complete elimination of AEs following ethanol (Group A). In 18 patients (Group B), cibenzoline failed to eliminate AEs; yet, in 13 of 18 AEs were eliminated by ethanol. In the remaining five patients, ethanol did not eliminate AE.

CONCLUSIONS

Cibenzoline into the VOM could reliably predicts the results of subsequent ethanol infusion into the VOM using ultrahigh-resolution mapping system, which leads to avoid unnecessary permanent lesion creation by ethanol infusion.

Usefulness of Cibenzoline Stress Echocardiography to Determine Severity of Aortic Stenosis in a Patient with Combined Left Ventricular Outflow Tract Obstruction and Aortic Stenosis

Left ventricular outflow tract obstruction (LVOTO) is sometimes accompanied by aortic stenosis (AS). Reliable estimation of the true severity of AS is often difficult because it cannot be discriminated from dual stenosis. A 75-year-old woman was referred to our hospital due to traumatic hemopneumothorax with exertional dyspnea. Echocardiography revealed AS and LVOTO by chance. A continuous Doppler echocardiography revealed a late-systolic peaking dagger-shaped profile with a 6.0 m/s of peak jet velocity across the LVOT and aortic valve, but it was difficult to discriminate between the coexisting peak flows. For an accurate evaluation of AS, we performed landiolol (short acting beta-blocker) and cibenzoline (Na⁺ channel-blocking agent) stress echocardiography with simultaneous recordings of both left ventricular and aortic pressure by catheter examination. Cibenzoline successfully eliminated the LVOTO, but landiolol did not. Cibenzoline stress echocardiography enabled us to evaluate the AS severity as less than moderate, resulting in proper decision-making. The findings in this case clearly showed that cibenzoline stress echocardiography has a potential utility for determining AS severity in a patient with coexistent dynamic LVOTO.

Impact of chronic use of cibenzoline on left ventricular pressure gradient and left ventricular remodeling in patients with hypertrophic obstructive cardiomyopathy

BACKGROUND

Cibenzoline, a class Ia antiarrhythmic drug, is useful for reducing the left ventricular pressure gradient (LVPG) in patients with hypertrophic obstructive cardiomyopathy (HOCM). However, chronic effects of cibenzoline on LVPG and left ventricular (LV) remodeling are unknown.

METHODS

Forty-one patients with HOCM participated in this study. Echocardiographic, electrocardiographic, and brain natriuretic peptide (BNP) data collected before and after cibenzoline treatment were compared. From the relation between LVPG and plasma concentration of cibenzoline, an efficacious plasma concentration of cibenzoline was estimated.

RESULTS

The mean follow-up period was 74.2±47.1 months. The LVPG decreased from 104.8±62.6mmHg to 27.6±30.5mmHg (p<0.0001). The LV end-diastolic dimension increased from 42.8±5.8mm to 46.2±5.4mm (p<0.0001), but neither LV end-systolic dimension nor LV fractional shortening changed significantly. The left atrial dimension decreased from 40.0±4.7mm to 36.2±5.1mm (p<0.0001). The E-wave velocity/A-wave velocity ratio increased, early diastolic annular velocity (Ea) increased, and E/Ea ratio decreased. The interventricular septal wall thickness, LV posterior wall thickness, the Sokolow-Lyon index, and the depth of negative T wave decreased. The heart rate-corrected QT interval was shortened. Plasma BNP level decreased from 418.8±423.7pg/ml to 213.7±154.1pg/ml (p<0.02). The safe and efficacious plasma concentration of cibenzoline was between 300ng/mL and 1500ng/mL.

CONCLUSIONS

Long-term treatment with cibenzoline attenuated LVPG, improved LV diastolic dysfunction, and induced LV hypertrophy regression in patients with HOCM without causing serious complications.

Relief of Left Ventricular Outflow Obstruction by Cibenzoline in a Patient With Fabry’s Disease

A 46-year-old man was admitted for further evaluation of exertional chest discomfort. One family member had experienced sudden death, and 2 others had died of heart failure, including 1 known to have had Fabry’s disease. The patient was also diagnosed with Fabry’s disease, based on reduced leukocyte a-galactosidase A activity, 2.0 nmol/mg protein/hour, as well as endomyocardial biopsy findings of marked sarcoplasmic vacuolization of cardiac muscle cells by light microscopy and lamellated “zebra bodies” in the cytoplasm shown by electron microscopy. Echocardiography disclosed marked left ventricular hypertrophy and systolic anterior motion of the mitral leaflets. On cardiac catheterization, a left ventricular peak systolic outflow gradient of 50 mm Hg was noted; this decreased to 10 mm Hg following intravenous administration of 100 mg of cibenzoline. It is imperative to recognize the existence of cases with Fabry’s disease associated with left ventricular outflow obstruction.

Computed tomography imaging to quantify the area of the endocardial subvalvular apparatus in hypertrophic cardiomyopathy - Relationship to outflow tract obstruction and symptoms

BACKGROUND

Abnormalities of the endocardial subvalvular apparatus (SVA), which includes the papillary muscles directly attached to the mitral leaflet and left ventricular apical-basal muscle bundles, are occasionally identified in hypertrophic cardiomyopathy (HCM). Their associations with left ventricular outflow tract (LVOT) obstruction are unknown.

METHODS

We retrospectively reviewed cardiac computed tomography image data sets of 107 consecutive patients with HCM [56 obstructive (HOCM) and 51 non-obstructive (HNOCM)] as well as 53 controls. We evaluated anomalies of the SVA, measured the cross-sectional area of the SVA at the level of the LVOT, and subsequently assessed its correlation with the LVOT pressure gradient with and without medication.

RESULTS

The area of the SVA was greater in HOCM than in HNOCM patients and in the control group (2.5 ± 1.3 cm(2), 1.4 ± 0.8 cm(2), and 0.9 ± 0.6 cm(2), respectively; p < 0.0001). Anomalies in the SVA were more often observed in the HOCM group than in the HNOCM patients and controls (abnormal papillary muscles, 14%, 8%, and 0%, respectively; P = 0.010; LV apical-basal muscle bundles, 73%, 65%, and 45%, respectively; P = 0.0094). Among HOCM patients, logistic regression analysis demonstrated that an SVA area of 2.2 cm(2) was an independent risk factor of residual severe LVOT obstruction (≥50 mmHg) after medication (odds ratio, 10.1; 95% confidence interval, 2.05-49.80).

CONCLUSION

An increased area of the endocardial subvalvular apparatus could be an independent risk factor for clinically relevant LVOT obstruction refractory to medication.

Elevated Cardiac Enzymes in Hypertrophic Cardiomyopathy Patients With Heart Failure - A 20-Year Prospective Follow-up Study

BACKGROUND

To better understand the evolution of typical hypertrophic cardiomyopathy (HCM) to heart failure (HF), we investigated the relationship between serum biochemical abnormalities and changes in left ventricular (LV) remodeling.

METHODS AND RESULTS

Seventy-seven HCM patients were followed for 20 years. Creatine kinase (CK), CK-MB, lactate dehydrogenase (LDH), LDH-1, troponin T and myosin light chain-1 (MLC-1) were measured. Abnormal CK-MB elevation was observed in 64% of HCM patients. LDH-1 was not significantly different compared with the control subjects. Troponin T elevation was observed in 3 HCM patients and MLC-1 elevation was not observed. According to median CK-MB, HCM patients were divided into 2 groups: group H (CK-MB ≥2.5%, n=33) and group L (CK-MB <2.5%, n=44). During the follow-up period in group H, LV end-diastolic dimension increased (P<0.0001), fractional shortening decreased (P<0.0004), and left atrial dimension increased (P<0.0001). The markers reflecting LV hypertrophy were significantly decreased. In group L, LV end-diastolic dimension increased (P<0.02) and left atrial dimension increased (P<0.0001). HF was observed in 18 patients in group H and in 4 in group L. There were 14 HF deaths in group H and 2 in group L, and 3 sudden cardiac deaths in group H.

CONCLUSIONS

Persistent elevation of cardiac enzymes in HCM patients indicates ongoing myocardial injury, ultimately resulting in death by HF.

Magnetic resonance imaging of microvascular obstruction in hypertrophic obstructive cardiomyopathy after percutaneous transluminal septal myocardial ablation

BACKGROUND

The clinical significance of microvascular obstruction (MO) in hypertrophic cardiomyopathy (HOCM) after percutaneous transluminal septal myocardial ablation (PTSMA) remains unknown.

PURPOSE

To assess the relationship between the location of MO and the improvement in symptoms and pressure gradient after PTSMA in patients with HOCM.

MATERIAL AND METHODS

Twenty-three patients with HOCM underwent MRI within 24 weeks after PTSMA. The MO was defined visually as the hypointense region adjacent to the left or right ventricular cavity, which was surrounded by myocardial infarction. The location of MO and improvement in clinical symptoms and pressure gradient at 3-6 months follow-up were assessed.

RESULTS

MO was observed in 16 patients who underwent MRI within 7 weeks after PTSMA. Left-sided MO was observed in 12 patients, and right-sided MO was observed in four patients. Improvement in clinical symptoms and reduction in the pressure gradient were not sufficient in the patients with right-sided MO, while PTSMA was effective in the patients with the left-sided MO.

CONCLUSION

The location of MO identified by MRI may be related to the effectiveness of PTSMA at the short-term follow-up. The left-sided MO is related to complete improvement in clinical symptoms and pressure gradients.

Contrast-enhanced Steady-state Free Precession in the Assessment of Hypertrophic Obstructive Cardiomyopathy after Alcohol Septal Ablation

PURPOSE

We evaluated the feasibility of contrast-enhanced steady-state free precession (ceSSFP) in the assessment of myocardial injury and obstruction of the left ventricular outflow tract (LVOT) in patients with hypertrophic obstructive cardiomyopathy (HOCM) after alcohol septal ablation (ASA).

METHODS

Twelve patients with HOCM underwent 16 magnetic resonance (MR) examinations following ASA. Precontrast SSFP, ceSSFP and late gadolinium enhancement (LGE) imaging were performed with a 1.5-tesla imager. ceSSFP was performed 3 to 7 min after gadolinium injection. We visually and quantitatively evaluated the signal patterns of the myocardium after ASA on SSFP and LGE MR imaging. We observed the LVOT using ceSSFP in the 3-chamber view.

RESULTS

We could visualize ASA-induced myocardial infarction (MI) in all 16 studies by LGE and ceSSFP but in only 6 studies (37.5%) by precontrast SSFP. Contrast was higher between MI and remote myocardium with LGE than ceSSFP (P < 0.01). ASA-induced hypointense regions were well visualized by the 2 sequences after contrast in the 7 patients who underwent MR imaging within 7 weeks of ASA and in a few patients after 80 weeks from ASA. The ceSSFP allowed comparable visualization of the jet flow crossing the LVOT to that derived from echocardiographic data.

CONCLUSION

Contrast-enhanced steady-state free precession allows assessment of myocardial injury as well as of the left ventricular outflow tract after alcohol septal ablation in a single scan without penalty in scan time and cine imaging contrast.

Takotsubo cardiomyopathy with transient left ventricular obstruction successfully treated with cibenzoline succinate: A case report

An 84-year-old woman was urgently referred to our hospital owing to persistent malaise and chest pain. Takotsubo cardiomyopathy was diagnosed following transthoracic echocardiography, emergency coronary angiography, and left ventriculography. A left ventricular pressure tracing during cardiac catheterization revealed a 72 mmHg-intraventricular pressure gradient (LVPG). Although β-blockers are effective at reducing LVPG in takotsubo cardiomyopathy, such treatment was contraindicated in our patient owing to her history of bronchial asthma. Therefore, we administered intravenous cibenzoline succinate to attenuate her LVPG. The LVPG decreased to 18 mmHg within 10 min after intravenous cibenzoline succinate administration. During her subsequent hospitalization, the patient showed excellent functional recovery, without any complications. Left ventriculography, performed 21 days after admission, showed normal wall motion and a left ventricular ejection fraction of 68%. <Learning objective: The prognosis of takotsubo cardiomyopathy is generally good, however, fatal complications have been reported. Our case demonstrated a LVPG of 72 mmHg, and β-blockers were contraindicated because of bronchial asthma. Intravenous cibenzoline administration resulted in successful attenuation of the patient's LVPG. The present case suggests that cibenzoline might be effective for the treatment of takotsubo cardiomyopathy, especially in those contraindicated for β-blocker therapy.>.

Reappearance of the left ventricular pressure gradient in a patient with hypertrophic obstructive cardiomyopathy

An 84-year-old woman diagnosed with hypertrophic obstructive cardiomyopathy (HOCM) was referred to our hospital due to chest pain associated with an increased level of troponin T. Following the administration of cibenzoline, the left ventricular outflow pressure gradient (LVPG) completely disappeared. Left ventricular pressure pullback tracing subsequently demonstrated the "reappearance" of the LVPG. Left ventriculography showed apical ballooning with excessive contractions at the base of heart, and we therefore made a diagnosis of Takotsubo cardiomyopathy in a patient with HOCM. Hypercontractions of the base of the heart associated with Takotsubo cardiomyopathy may be responsible for the "reappearance" of LVPG in this case.

Advances in medical treatment of hypertrophic cardiomyopathy

We reviewed the natural history of patients with hypertrophic cardiomyopathy (HCM). The effect of medical treatments on natural history, left ventricular (LV) functions and LV remodeling was also evaluated. Sudden cardiac death and end-stage heart failure are the most serious complications of HCM. Age <30 years and a family history of sudden premature death are risk factors for sudden cardiac death in HCM patients. End-stage heart failure is not a specific additional phenomenon observed in patients with HCM, but is the natural course of the disease in most of those patients. After the occurrence of heart failure, the progression to cardiac death is very rapid. Young age at diagnosis, a family history of HCM, and greater wall thickness are associated with a greater likelihood of developing end-stage heart failure. Neither beta-blockers nor calcium antagonists can prevent this transition. The class Ia antiarrhythmic drugs, disopyramide and cibenzoline are useful for the reduction of LV pressure gradient. Unlike disopyramide, cibenzoline has little anticholinergic activity; therefore, this drug can be easily adapted to long-term use. In addition to the reduction in LV pressure gradient, cibenzoline can improve LV diastolic dysfunction, and induce regression of LV hypertrophy in patients with HCM. A decrease in intracellular Ca(2+) concentration through the activation of the Na(+)/Ca(2+) exchanger associated with cibenzoline therapy is likely to be closely related with the improvement in HCM-related disorders. It is possible that cibenzoline can prevent the progression from typical HCM to end-stage heart failure.

Increased mean platelet volume in hypertrophic cardiomyopathy

Thromboembolic events may be seen in patients with hypertrophic cardiomyopathy (HCM). We investigated the mean platelet volume (MPV), an indicator of platelet activation in patients with HCM. This study included 112 patients with HCM, in which 40 were patients with hypertrophic obstructive cardiomyopathy (HOCM), and 106 were control participants. The MPV was significantly higher in patients with HCM than in controls (9.1 ± 0.3 vs 7.9 ± 0.3 fL, P = .01). In the subgroup analyses, MPV was also higher in patients with HOCM compared to those with hypertrophic nonobstructive cardiomyopathy (HNCM; 9.3 ± 0.3 vs 9.0 ± 0.2 fL, P = .01). Similarly, patients with HNCM had higher MPV values than controls (9.0 ± 0.2 vs 7.9 ± 0.3 fL, P = .01). The MPV was significantly and positively correlated with left ventricular outflow tract (LVOT) obstruction (r = .42, P = .001) and septal thickness (r =.62, P = .001). In linear regression analysis, MPV was independently associated only with septal thickness (β = .07, 95% confidence interval: 0.04-0.09, P = .001). The MPV can be elevated in patients with HCM regardless of the obstruction of LVOT and may be associated with the severity of septal thickness.

Mid-ventricular obstruction occurred in hypertrophic left ventricle of heterozygous Fabry's disease-Favorable effects of cibenzoline: A case report

A 54-year-old woman visited our hospital because of palpitation and dizziness. Systolic ejection murmur, Levine IV/VI, was heard at the left sternal border and atrial gallop was auscultated at apex. Echocardiogram demonstrated diffuse hypertrophy of the left ventricular walls extending to the apex. The left ventricular walls increased symmetrically; the septal and the posterior wall measured approximately 26 mm and 30 mm in thickness, respectively. Apical two-chamber views revealed a narrow outflow of the left ventricular cavity at apex with a distinct convergence zone, where color flow Doppler imaging showed turbulent jet flow from mid to late systole. The leukocyte α-galactosidase A activity was lower than normal. Percutaneous endomyocardial biopsy showed specific change for Fabry's disease by electron microscopy. On cardiac catheterization, mid-ventricular resting pressure gradient of approximately 90 mmHg was shown. This pressure gradient dramatically disappeared after intravenous administration of 70 mg of cibenzoline. We describe a rare case of Fabry's disease that revealed diffuse hypertrophy having dynamic obstruction at mid-left ventricle, like mid-ventricular obstruction, and the administration of cibenzoline had beneficial effects on pressure gradient of mid-left ventricle.

Successful electrical cardioversion in a massive concentric hypertrophic cardiomyopathy with atrial fibrillation

A 59-year-old man with a known history of nonobstructive hypertrophic cardiomyopathy and chronic atrial fibrillation was admitted to our clinic with weakness, palpitation, and exertional dyspnea. Electrocardiogram showed atrial fibrillation with high ventricular rate (120 beats per minute), intraventricular conduction delay, and left ventricular (LV) hypertrophy with ST-segment depression and inverted T waves. A transthoracic echocardiogram showed massive LV concentric hypertrophy. Although there was no gradient increase in the LV outflow tract, marked turbulent flow was seen in midventricular region by colored Doppler echocardiography. On the fourth day of admission, transesophageal echocardiography was done and showed no thrombus in the left atrium. Electrical cardioversion with 100 J was applied to the patient, and atrial fibrillation was returned to sinus rhythm. His control Doppler echocardiogram revealed peak systolic resting gradient of 54 mm Hg, with an increase to 84 mm Hg at Valsalva maneuver at the LV outflow. Cardiac magnetic resonance showed concentric LV hypertrophy with a 35-mm thickness in diastole, mild scar tissue in LV anterior wall midapical segments, and right ventricle wall thickness with a 10 mm in diastole. There was no bradycardia or tachycardia in 24-hour Holter and exercise electrocardiographic testing.

Comparison of acute reduction in left ventricular outflow tract pressure gradient in obstructive hypertrophic cardiomyopathy by disopyramide versus pilsicainide versus cibenzoline

Negative inotropic agents are often administered to decrease the left ventricular (LV) pressure gradient in patients with obstructive hypertrophic cardiomyopathy (HC). Little information is available regarding comparisons of the effects on LV pressure gradient among negative inotropic agents. The present study compared the decrease in the LV pressure gradient at rest in patients with obstructive HC after treatment with pilsicainide versus treatment with disopyramide or cibenzoline. The LV pressure gradient and LV function were assessed before and after the intravenous administration of each drug. In 12 patients (group A, mean pressure gradient 90 ± 24 mm Hg), the effects of disopyramide, propranolol, and verapamil were compared. In another 12 patients (group B, mean pressure gradient 98 ± 34 mm Hg), a comparison was performed among disopyramide, cibenzoline, and pilsicainide. In group A, the percentage of reduction in the LV pressure gradient was 7.7 ± 9.9% with verapamil, 19.0 ± 20.2% with propranolol, and 58.6 ± 15.0% with disopyramide, suggesting that disopyramide was more effective than either verapamil or propranolol. In group B, the percentage of reduction in the LV pressure gradient was 55.3 ± 26.6% with disopyramide, 55.3 ± 20.6% with cibenzoline, and 54.7 ± 15.4% with pilsicainide, suggesting an equivalent effect on the LV pressure gradient for these 3 agents. In conclusion, these results indicate that the acute efficacy for the reduction of the LV pressure gradient at rest by pilsicainide (a pure sodium channel blocker) was equivalent to that of disopyramide or cibenzoline (combined sodium and calcium channel blockers). Accordingly, sodium channel blockade might be more important for reducing the LV pressure gradient at rest in patients with obstructive HC than calcium channel blockade or β blockade.

Pharmacogenetic interactions between Angiotensin-converting enzyme insertion/deletion polymorphism and response to cibenzoline in patients with hypertrophic obstructive cardiomyopathy

Cibenzoline, a Class I antiarrhythmic agent, can attenuate the left ventricular pressure gradient (LVPG) in patients with hypertrophic obstructive cardiomyopathy (HOCM). An association between the insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE) gene and the progression of left ventricular hypertrophy in patients with hypertrophic cardiomyopathy has been reported. The aim of this study was to investigate the pharmacogenetic interactions between the ACE insertion/deletion polymorphism and the response to cibenzoline in patients with HOCM. Twenty-four patients with HOCM participated in this study. The LVPG and left ventricular function were measured by echocardiography before and 2 hours after administration of a single oral dose of 200 mg cibenzoline. The ACE insertion/deletion polymorphism was genotyped. The frequencies of the genotypes D/D, D/I, and I/I were 16%, 42%, and 42%, respectively. Before administration of cibenzoline, the LVPG was higher in patients with the D allele than in those without it (105 +/- 47 mm Hg versus 64 +/- 24 mm Hg, P = 0.0195). After administration of cibenzoline, the LVPG significantly decreased to 41 +/- 27 mm Hg in those with the D allele (P = 0.0001) and to 33 +/- 24 mm Hg in those without it (P = 0.0003). The LVPG in patients with the D allele was significantly decreased by cibenzoline when compared with patients without the allele (64 +/- 45 mm Hg versus 31 +/- 17 mm Hg, P = 0.038). Patients with HOCM with the ACE D allele had a high LVPG. Cibenzoline was more effective in patients with HOCM with the ACE D allele.

Effect of cibenzoline on biventricular pressure gradients in a pediatric patient with hypertrophic obstructive cardiomyopathy

This report presents the case of an 8-year-old male with biventricular hypertrophic obstructive cardiomyopathy who achieved a successful reduction of the pressure gradients by treatment with cibenzoline. Ultrasound echocardiography showed marked intraventricular septal hypertrophy and left midventricular and right ventricular outflow obstructions. A cardiac catheterization revealed left midventricular and right outflow obstructions associated with pressure gradients of 100 and 35 mmHg, respectively. An intravenous injection of 28 mg (1.4 mg/kg) cibenzoline immediately improved the biventricular pressure gradients. Therefore, oral cibenzoline treatment was initiated, the dose was increased to 150 mg/day, and both pressure gradients remained low, without any complications at the time of discharge, 4 months later.

Cibenzoline attenuates systolic anterior motion of the mitral valve after mitral valvoplasty

We report a patient in whom severe hemodynamic instability occurring after mitral valvoplasty (MVP) was successfully treated with cibenzoline. Left ventricular outflow tract obstruction (LVOTO) with mitral regurgitation (MR) resulting from the systolic anterior motion (SAM) of the mitral valve that occurs after MVP often leads to hemodynamic collapse. Patients who develop SAM after MVP have been managed with intravenous volume loading, reduction/discontinuation of inotropic drugs, and with increased afterload, but these strategies were often ineffective. Cibenzoline decreased myocardial contraction, attenuated SAM, and improved hemodynamics in our patient. We recommend that cibenzoline be administered before further surgical manipulation is considered for patients who develop SAM after MVP.

QRS prolongation is associated with high defibrillation thresholds during cardioverter-defibrillator implantations in patients with hypertrophic cardiomyopathy

BACKGROUND

Although high defibrillation threshold (DFT) is a major and unavoidable clinical problem after implantation of an implantable cardioverter defibrillator (ICD), little is known about the cause and management of a high DFT in patients with hypertrophic cardiomyopathy (HCM). The purpose of this study was to assess the predictors of a high DFT in patients with HCM.

METHODS AND RESULTS

Twenty-three patients with non-dilated HCM who underwent ICD implantation were included. The DFT at the time of the device implantation was measured in all patients. The patients were divided into 2 groups, a high DFT group (DFT >or=15J, n=13) and a low DFT group (DFT <15J, n=10); and their baseline characteristics were compared. The QRS duration was longer in the high than in the low DFT group (128 +/-31 vs 103 +/-12 ms, respectively; P=0.02). QRS duration, left ventricular (LV) end-systolic diameter, and LV ejection fraction were significant predictors of DFT in univariate analysis. However, in multivariate analysis, the only factor significantly associated with DFT was QRS duration (P=0.002).

CONCLUSIONS

QRS duration is the most consistent predictor of a high DFT in HCM patients undergoing ICD implantation.

Effect of cibenzoline on regional left ventricular function in hypertrophic obstructive cardiomyopathy

BACKGROUND

Cibenzoline, a class Ia antiarrhythmic drug, can be used to relieve left ventricular (LV) outflow obstruction in hypertrophic obstructive cardiomyopathy (HOCM). However, the mechanism of this agent in HOCM has been controversial.

HYPOTHESIS

This study was designed to investigate the effect of cibenzoline on regional LV function and the acoustic properties in HOCM using ultrasonic integrated backscatter.

METHODS

Ten patients with HOCM and 16 healthy volunteers were examined. In patients with HOCM, wall thickening (%WT) and the magnitude of cyclic variation of integrated backscatter (mag-CVIBS) in the interventricular septum (IVS) and LV posterior wall were measured before and after oral administration of cibenzoline. To assess asynchrony of contractile elements, the phase difference between CVIBS and %WT were measured from the LV posterior wall. Pressure gradients at the LV outflow tract were estimated using continuous-wave Doppler echocardiography.

RESULTS

Although %WT decreased significantly in the LV posterior wall, %WT and mag-CVIBS remained unchanged in the IVS. The phase difference in the LV posterior wall was significantly greater in patients with HOCM than in healthy volunteers (HOCM:healthy volunteers, 1.57 +/- 0.23:1.00 +/- 0.03, p < 0.001) at baseline. After administration of cibenzoline, the phase difference shifted to normal value (from 1.57 +/- 0.23 to 1.28 +/- 0.27, p = 0.0382), and pressure gradients at the LV outflow tract decreased (from 109 +/- 55 to 58 +/- 48 mmHg, p = 0.0063). Changes in pressure gradients at the LV outflow tract and the phase difference were closely related.

CONCLUSIONS

Regional function and the acoustic properties of myocardium in HOCM were altered by cibenzoline in the LV posterior wall but remained unchanged in the IVS. The normalization of the phase difference in the LV posterior wall was closely related to the decrease in pressure gradients at the LV outflow tract. These findings suggest that negative inotropic action and the improvement of asynchrony in the LV posterior wall rather than in the IVS may contribute to the reduction of pressure gradients at the LV outflow tract in HOCM.

Dobutamine stress echocardiography unmasks acute worsening of mitral regurgitation with latent left ventricular outflow tract obstruction behind diastolic heart failure in hypertensive heart disease

In a 57-year-old woman who was referred as refractory diastolic heart failure, dobutamine stress echocardiography facilitated the diagnosis of acute worsening of mitral regurgitation accompanied with latent left ventricular outflow tract obstruction as a cause of recurrent flash pulmonary edema. Echocardiography revealed the presence of sigmoid septum and concentric left ventricular hypertrophy, being consistent with hypertensive heart disease. Dobutamine induced systolic anterior motion of the mitral valve (SAM) with massive mitral regurgitation, resulting in sudden hypotension with dyspnea. The class Ia antiarrhythmic drug, cibenzoline, reduced the SAM during a dobutamine stress test, followed by no recurrence of flash pulmonary edema.

Impact of percutaneous transluminal septal myocardial ablation on refractory paroxysmal atrial fibrillation in patients with hypertrophic obstructive cardiomyopathy

Atrial fibrillation is commonly observed in patients with hypertrophic obstructive cardiomyopathy. Episodes of paroxysmal atrial fibrillation are often torturous and limit the quality of life by causing congestive heart failure, transient hypotension, or bradycardia. Control of paroxysmal atrial fibrillation in patients with hypertrophic obstructive cardiomyopathy is considered to be important for symptomatic improvement and prevention of the development to chronic atrial fibrillation. The authors report on 3 patients with hypertrophic obstructive cardiomyopathy who suffered from paroxysmal atrial fibrillation despite receiving medical treatment using antiarrhythmic agents. However, after undergoing percutaneous transluminal septal myocardial ablation, the incidence of episodes became significantly less frequent. Percutaneous transluminal septal myocardial ablation is normally performed for attenuating left ventricular obstruction by reducing the systolic anterior motion of the mitral leaflet. However, in these patients, this procedure was also effective in preventing supraventricular arrhythmia, probably by improving left ventricular diastolic dysfunction, smooth blood inflow into the left ventricular, and decreasing the pressure stress against the left atrial wall.