Disopyramide is a safe and effective treatment for children with obstructive hypertrophic cardiomyopathy

BACKGROUND

Left ventricular outflow tract obstruction (LVOTO) is present in 1/3 of children with Hypertrophic Cardiomyopathy (HCM). Disopyramide improves symptoms associated with LVOTO and delays surgical intervention in adults, but it is not licensed in children.

AIM

To describe a single-centre thirty-year experience of using disopyramide to treat LVOTO-related symptoms in a paediatric HCM cohort.

METHODS

Clinical data were collected for all patients meeting diagnostic criteria for HCM (<18 years) at the time of initiation, 6 months after, and last follow-up or end of disopyramide treatment. It included demographics, clinical history, 12‑lead electrocardiography, and echocardiography. Comparisons between baseline and 6 month follow up, and end of follow up respectively were performed.

RESULTS

Fifty-one patients with HCM were started on disopyramide at a mean age 10.2±5.3 years. At 6 months, of those previously symptomatic, 33(86.8%) reported an improvement of symptoms and 12(31.6%) were asymptomatic. PR interval, corrected QT interval and maximal LVOT gradient had not significantly changed, but fewer participants were noted to have systolic anterior motion of the mitral valve 31 (72.1%) vs. 26 (57.80%). Patients were followed up for a median of 1.9 years (IQR 0.83-4.5). Nine patients (17.6%) reported side effects, and eleven patients (33.3%) with initial improvement in symptoms reported a return or worsening of symptoms requiring a change in medication (n = 4, 12.1%) or left ventricular septal myomectomy (n = 7, 21.2%) during follow up.

CONCLUSION

Disopyramide is a safe and effective treatment for LVOTO-related symptoms in childhood obstructive HCM. Any delay in the need for invasive intervention, particularly during childhood, is of clear clinical benefit.

Structure-activity relationship and cardiac safety of 2-aryl-2-(pyridin-2-yl)acetamides as a new class of broad-spectrum anticonvulsants derived from Disopyramide

A series of 2-aryl-2-(pyridin-2-yl)acetamides were synthesized and screened for their anticonvulsant activity in animal models of epilepsy. The compounds were broadly active in the 'classical' maximal electroshock seizure (MES) and subcutaneous Metrazol (scMET) tests as well as in the 6 Hz and kindling models of pharmacoresistant seizures. Furthermore, the compounds showed good therapeutic indices between anticonvulsant activity and motor impairment. Structure-activity relationship (SAR) trends clearly showed the highest activity resides in unsubstituted phenyl derivatives or compounds having ortho- and meta- substituents on the phenyl ring. The 2-aryl-2-(pyridin-2-yl)acetamides were derived by redesign of the cardiotoxic sodium channel blocker Disopyramide (DISO). Our results show that the compounds preserve the capability of the parent compound to inhibit voltage gated sodium currents in patch-clamp experiments; however, in contrast to DISO, a representative compound from the series 1 displays high levels of cardiac safety in a panel of in vitro and in vivo experiments.

Markers of responsiveness to disopyramide in patients with hypertrophic cardiomyopathy

BACKGROUND

Significant left-ventricular outflow tract obstruction (LVOTO) in hypertrophic cardiomyopathy (HCM) may result in symptoms and is associated with adverse outcomes. Although disopyramide can reduce resting gradients, nearly 30% of HCM patients do not respond. We sought to study the clinical and echocardiographic variables associated with disopyramide-induced LVOT-gradient reduction.

METHODS

Forty-one disopyramide-treated HCM patients (average daily-dose 305 mg) were subdivided into two groups: (1) nineteen responders, with a reduction of LVOT-gradients of at least 30% from baseline, and (2) twenty-two non-responders, in whom LVOT-gradients did not change or increased following treatment. All patients had a thorough clinical and echocardiographic assessment pre- and post-treatment initiation.

RESULTS

Patients who responded to disopyramide had better pretreatment left ventricular (LV) systolic function (LV ejection fraction of 67.9 ± 5.6% vs. 59.7 ± 5.8%, p = 0.0001), better LV global longitudinal strain (-17.9 ± 2.3% vs. -16.1 ± 2.5%, p = 0.048), less mitral regurgitation, smaller LV size (indexed LV end-systolic volume of 16.2 ± 5.1 ml/m² vs. 23.2 ± 6.8 ml/m², p = 0.001), and lower LV maximal wall thickness (17.2±3 mm vs.19.2 ± 3.4 mm, p = 0.046). Baseline left atrial (LA) volumes were significantly lower in the responders, with higher indices of LA ejection fraction (62 ± 11.2% vs. 50.5 ± 12.2%, p = 0.005), systolic LA strain (34 ± 12.4% vs. 25.8 ± 10.6%, p = 0.04), and LA strain-rate (1.34 ± 0.49%/sec vs. 0.99 ± 0.24%/sec, p = 0.012). In multivariable analysis, the presence of reduced LV systolic function and systolic LA strain-rate remained independently associated with poor response to disopyramide.

CONCLUSIONS

Obstructive HCM patients with more severe disease at baseline tend to respond less to disopyramide treatment. In those patients, early referral for alcohol septal ablation or myectomy surgery should be considered.

Lifestyle Modification and Medical Management of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy is a heterogenous condition associated with a myriad of symptoms. Just as in other disease states, the aim of medical therapy is the alleviation of suffering, improvement of longevity, and the prevention of complications. This article focuses on the associated comorbidities seen in patients with hypertrophic cardiomyopathy, potential lifestyle interventions, and conventional medical treatments for symptomatic hypertrophic cardiomyopathy.

A rapid and sensitive liquid chromatography/tandem mass spectrometry assay for simultaneous quantitation of disopyramide and its major metabolite, mono-isopropyl-disopyramide, in rat plasma and its application to a pharmacokinetic study

Disopyramide as an antiarrhythmic agent has been used for treating ventricular tachycardia and metabolized into its major metabolite, mono-isopropyl-disopyramide, by CYP3A4. We developed a novel, selective, highly sensitive, accurate, rapid method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of disopyramide and mono-isopropyl-disopyramide in rat plasma. This study is the first report for the assay validation using LC-MS/MS in biological fluids after simple protein-precipitation method. The most sensitive signals by multiple reaction monitoring (MRM) showed at m/z 340.2 → 239.2 and 298.2 → 239.2 with same fragment ion for disopyramide and mono-isopropyl-disopyramide, respectively. The lower limit of quantification (LLOQ) was determined at 2 ng/mL for both analytes and the linear concentration ranges were found to be 2-2000 ng/mL for disopyramide and 2-1000 ng/mL for mono-isopropyl-disopyramide. Finally, this assay was successfully applied to pharmacokinetic analysis of disopyramide and mono-isopropyl-disopyramide after oral and intravenous administration of disopyramide.

Disopyramide as rescue treatment in a critically ill infant with obstructive hypertrophic cardiomyopathy refractory to beta blockers

Hypertrophic obstructive cardiomyopathy (HOCM) is the most common known cause of sudden death in children beyond infancy and in young athletes. Cases reported indicate that steroid-induced HOCM is usually a benign disorder. The normalization of cardiac morphological changes and clinical signs observed after the discontinuation of steroid therapy indicates that the effects on cardiac muscle are dose-dependent and reversible. However, the management of patients with symptomatic-HOCM presenting in infancy represents a major challenge because left ventricular outflow tract obstruction is a major risk factor associated with increased mortality in pediatric patients. We report a critically ill infant with steroid-induced HOCM resistant to beta-blockers who was successfully treated with disopyramide without relevant adverse events. Adult guidelines and pediatric experts suggest pharmacological therapy with beta-blockers or verapamil as the first- and second-line approach. However, these drugs are not always an option, especially in critical patients, hence, alternative therapeutic options are required. For these cases, disopyramide could be an alternative drug in spite of the little evidence on its safety and efficacy in pediatric patients. Our experience supports this cause, and the need for prospective studies on its use in the management of hypertrophic cardiomyopathy in children. <Learning objective: Patients with symptomatic-HOCM resistant to first-line therapy with beta-blockers represent a challenge and are often referred for advanced care. In children, many authors suggest that disopyramide in combination with beta-blockers could be a useful adjunct therapy option in these cases, resulting in decrease of left ventricular outflow tract obstruction, symptoms, and survival improvement, without significant pro-arrhythmia mortality.>.

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.

Molecular modeling, docking and ADMET studies towards development of novel Disopyramide analogs for potential inhibition of human voltage gated sodium channel proteins

The sodium "channelopathies" are the first among the ion channel diseases identified and have attracted widespread clinical and scientific interests. Human voltage gated sodium channels are sites of action of several antiarrhythmic drugs, local anesthetics and related antiepileptic drugs. The present study aims to optimize the activity of Disopyramide, by modification in its structures which may improve the drug action by reducing its side effects. Herein, we have selected Human voltage-gated sodium channel protein type 5 as a potent molecular target. Nearly eighty analogs of Disopyramide are designed and optimized. Thirty are selected for energy minimization using Discovery studio and the LigPrep 2.5. Prior to docking, the active sites of all the proteins are identified. The processing, optimization and minimization of all the proteins is done in Protein preparation wizard. The docking study is performed using the GLIDE. Finally top five ranked lead molecules with better dock scores are identified as having strong binding affinity to 2KAV protein than Disopyramide based on XP G scores. These five leads are further docked with other similar voltage gated sodium channel proteins (PDB IDs: 2KBI, 4DCK, 2L53 and 4DJC) and the best scoring analog with each protein is identified. Drug likeliness and comparative bioactivity analysis for all the analogs is done using QikProp 3.4. Results have shown that the top five lead molecules would have the potential to act as better drugs as compared to Disopyramide and would be of interest as promising starting point for designing compounds against various Sodium channelopathies.

Interactions of rosiglitazone and anti-arrhythmic drugs in animal model

BACKGROUND

Diabetes increases the risk of vascular problems by two times compared with a healthy individual, with deposition of fats in blood vessel and this includes cardiovascular disease. The treatment regimens for patients suffering from both diseases generally include prolonged use of anti-diabetic drugs for diabetes and anti-arrhythmic drugs for cardiac arrhythmias.

AIM

The aim of the study is to compare the influence of Mexiletine and Disopyramide on the pharmacodynamics (PDs) of Rosiglitazone in normal and diabetic rats.

MATERIALS AND METHODS

The study was conducted in normal rats and diabetic induced rats (with Alloxan monohydrate 100 mg/kg body weight). Albino rats weighing between 160 and 280 g were administered oral doses of Rosiglitazone 0.72 mg/kg, Mexiletine 36 mg/kg, or Disopyramide 18 mg/kg of bodyweight and their combination, with 1 week of washout between treatments. Eighteen rats were divided into three sub-sets with six rats in each sub-set. After 4 days, the blood glucose was estimated to confirm the diabetes. The Analysis of Covariance (ANCOVA) using MedCalc(®) software Version 11.6.1.0 was performed to analyze mean change in blood glucose between treatments with body weight as co-variable and treatment as factor for normal and diabetic rats.

RESULTS

No statistically significant difference in mean change in blood glucose between Rosiglitazone in comparison with Rosiglitazone + Mexiletine or Rosiglitazone + Disopyramide was observed in normal and diabetic rats (P = 0.606). The maximum mean change in blood glucose for Rosiglitazone and Rosiglitazone + Mexiletine or Rosiglitazone + Disopyramide was observed at 1 h and 8 h in normal and diabetic rats. The post hoc analysis showed baseline correction method has increased the reliability of the results (P < 0.001).

CONCLUSION

The study concludes that PD activity of Rosiglitazone was not affected by the anti-arrhythmic drugs. This study introduced a new statistical methodology for analyzing the blood glucose endpoint.