Salutary effect of disopyramide on left ventricular diastolic function in 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.

Medical Therapies to Improve Left Ventricular Outflow Obstruction and Diastolic Function in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy-both obstructive hypertrophic cardiomyopathy (oHCM) and nonobstructive hypertrophic cardiomyopathy (nHCM) subtypes-is the most common monogenic cardiomyopathy. Its structural hallmarks are abnormal thickening of the myocardium and hyperdynamic contractility, while its hemodynamic consequences are left ventricular outflow tract or intracavitary obstruction (in oHCM) and diastolic dysfunction (in both oHCM and nHCM). Several medical therapies are routinely used to improve these abnormalities with the goal to decrease symptom burden in patients with HCM. Current guidelines recommend nonvasodilating beta blockers as first-line and nondihydropyridine calcium channel blockers followed by disopyramide as second- and third-line medical therapies for symptomatic oHCM and give weaker recommendations for beta blockers and calcium channel blockers in nHCM. These recommendations are based on small studies-mostly nonrandomized-and expert opinion. Our review will summarize the available data on the effectiveness of commonly prescribed medications used in oHCM and nHCM to uncover knowledge gaps, but also new data on cardiac myosin inhibitors.

Multi-modality management of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant inherited condition defined by left ventricular wall thickness greater than 15 mm in the absence of other conditions that could explain that degree of hypertrophy. Obstructive HCM associated with left ventricular outflow tract obstruction is defined by an intraventricular systolic pressure gradient greater than or equal to 30 mm Hg. Over the past couple of decades, there has been an expansion of both invasive and pharmacotherapeutic options for patients with HCM, with recent guidelines calling for a melody of invasive and non-invasive treatment strategies. There are several invasive therapies including proven therapies such as alcohol septal ablation and septal myectomy. Novel invasive therapies such as MitraClip, radiofrequency septal ablation and SESAME procedure have more recently been promoted. Pharmacological therapy has also dramatically evolved and includes conventional medications such as beta-blockers, calcium channel blockers, and disopyramide. Mavacamten, a novel cardiac myosin inhibitor, may significantly change management. Other myosin inhibitors and modulators are also being developed and tested in large clinical trials. Given significant phenotypical variability in patients with HCM, clinical management can be challenging, and often requires an individualized approach with a combination of invasive and non-invasive options.

Impact of Short-Acting Disopyramide on Left Ventricular Mechanics Evaluated by Strain Analysis in Patients with Hypertrophic Obstructive Cardiomyopathy

Background: Disopyramide is a class Ia antiarrhythmic drug that has been used for the second-line treatment of symptomatic hypertrophic obstructive cardiomyopathy (HOCM). The aim of the study was to assess the impact of short-acting disopyramide in patients with hypertrophic obstructive cardiomyopathy (HOCM) using two-dimensional speckle-tracking echocardiography. Methods: This prospective study included patients with HOCM on chronic treatment with short-acting disopyramide. Two sequential comprehensive echocardiographic examinations were performed: after temporary disopyramide suspension and 2.5 h after disopyramide intake. Results: 19 patients were included in the study. The effect of disopyramide on the left ventricle was not uniform. After the intake of disopyramide, the mean global strain peak was −17 ± 2% before disopyramide intake and −14 ± 2% after (p < 0.0001). There was a significant reduction in strain in the basal septal (p = 0.015), basal inferior (p = 0.019), basal posterior (p = 0.05), apical anterior (p = 0.0001), and apical lateral segments (p = 0.021). In all other segments, there was no significant change. Disopyramide also caused a significant accentuation of the base-apex strain gradients (p = 0.036). No change was noted in circumferential and left atrial strain. While the left ventricular ejection fraction and outflow gradients did not change, the significant reduction in global and segmental longitudinal strain demonstrated the acute negative inotropic effect of disopyramide on the myocardium in patients with HOCM. Conclusion: A strain analysis may be a useful tool to assess the negative inotropic effect of cardiovascular medication on the left ventricle in patients with HOCM.

Pharmacological Management of Hypertrophic Cardiomyopathy: From Bench to Bedside

Hypertrophic cardiomyopathy (HCM), the most common inherited heart disease, is still orphan of a specific drug treatment. The erroneous consideration of HCM as a rare disease has hampered the design and conduct of large, randomized trials in the last 50 years, and most of the indications in the current guidelines are derived from small non-randomized studies, case series, or simply from the consensus of experts. Guideline-directed therapy of HCM includes non-selective drugs such as disopyramide, non-dihydropyridine calcium channel blockers, or β-adrenergic receptor blockers, mainly used in patients with symptomatic obstruction of the outflow tract. Following promising preclinical studies, several drugs acting on potential HCM-specific targets were tested in patients. Despite the huge efforts, none of these studies was able to change clinical practice for HCM patients, because tested drugs were proven to be scarcely effective or hardly tolerated in patients. However, novel compounds have been developed in recent years specifically for HCM, addressing myocardial hypercontractility and altered energetics in a direct manner, through allosteric inhibition of myosin. In this paper, we will critically review the use of different classes of drugs in HCM patients, starting from "old" established agents up to novel selective drugs that have been recently trialed in patients.

Effects of Metoprolol on Exercise Hemodynamics in Patients With Obstructive Hypertrophic Cardiomyopathy

BACKGROUND

The relationship between exercise hemodynamics, loading conditions, and medical treatment in patients with obstructive hypertrophic cardiomyopathy (HCM) is incompletely understood.

OBJECTIVES

This study aimed to investigate the effect of metoprolol on invasive hemodynamic parameters at rest and during exercise in patients with obstructive HCM.

METHODS

This randomized, double-blind, placebo-controlled crossover trial enrolled 28 patients with obstructive HCM and New York Heart Association functional class ≥II. Patients were randomized to initiate either metoprolol 150 mg or placebo for 2 consecutive 2-week periods. Right-heart catheterization and echocardiography were performed at rest and during exercise at the end of each treatment period. The primary outcome was the difference in pulmonary capillary wedge pressure (ΔPCWP) between peak exercise and rest.

RESULTS

No treatment effect on ΔPCWP was observed between metoprolol and placebo treatment (21 ± 9 mm Hg vs 23 ± 9 mm Hg; P = 0.12). At rest, metoprolol lowered heart rate (P < 0.0001), left ventricular outflow tract (LVOT) gradient (P = 0.01), and increased left ventricular end-diastolic volume (P = 0.02) and stroke volume (SV) (+6.4; 95% CI: 0.02-17.7; P = 0.049). During peak exercise, metoprolol was associated with a lower heart rate (P < 0.0001), a lower LVOT gradient (P = 0.0005), lesser degree of mitral regurgitation (P = 0.004), and increased SV (+9 mL; 95% CI: 2-15 mL; P = 0.008).

CONCLUSIONS

In patients with obstructive HCM, exercise was associated with an abnormal rise in PCWP, which was unaffected by metoprolol. However, metoprolol increased SV at rest and peak exercise following changes in end-diastolic volume, LVOT gradient, and degree of mitral regurgitation. (The Effect of Metoprolol in Patients With Hypertrophic Obstructive Cardiomyopathy [TEMPO]; NCT03532802).

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.

Drug Therapy for Hypertrophic Cardiomypathy: Physiology and Practice

HCM is the most common inherited heart condition occurring in 1:500 individuals in the general population. Left ventricular outflow obstruction at rest or after provocation occurs in 2/3 of HCM patients and is a frequent cause of limiting symptoms. Pharmacologic therapy is the first-line treatment for obstruction, and should be aggressively pursued before application of invasive therapy. Beta-blockade is given first, and up-titrated to decrease resting heart rate to between 50 and 60 beats per minute. However, beta-blockade is not expected to decrease resting gradients; its effect rests on decreasing the rise in gradient that accompanies exercise. For patients who fail beta-blockade the addition of oral disopyramide in adequate dose often will decrease resting gradients and offer meaningful relief of symptoms. Disopyramide vagolytic side effects, if they occur, can be greatly mitigated by simultaneous administration of oral pyridostigmine. This combination allows adequate dosing of disopyramide to achieve therapeutic goals. Verapamil utility in obstructive HCM with high resting gradients is limited by its vasodilating effects that can, infrequently, worsen gradient and symptoms. As such, we tend to avoid it in patients with high gradients and limiting heart failure symptoms. In a head-to-head comparison of intravenous drug administration in individual obstructive HCM patients the relative efficacy for lowering gradient was disopyramide > beta-blockade > verapamil. Severe symptoms in non-obstructive HCM are caused by fibrosis or severe myocyte disarray, and often by very small LV chamber size. Severe symptoms caused by these anatomic and histologic abnormalities, in the absence of obstruction, are less amenable to current pharmacotherapy. New pharmacotherapeutic approaches to HCM are on the horizon, that are to be evaluated in formal therapeutic trials.

Beta-Blockers in Pediatric Hypertrophic Cardiomyopathies

Congestive cardiac failure accounts for 36% of childhood deaths in hypertrophic cardiomyopathy, and in infants with heart failure symptoms before two years of age, the mortality is extremely high unless treatment with beta-receptor antagonists is instituted. The mechanism of heart failure is not systolic dysfunction, but rather extreme diastolic dysfunction leading to high filling pressures.

Risk factors for development of heart failure are a generalized pattern of hypertrophy with a left ventricular posterior wall-to-cavity ratio >0.30, the presence of left ventricular outflow tract obstruction at rest, and the co-existence of syndromes in the Noonan/Leopard/Costello spectrum. The 5-year survival of high-risk patients is improved from 54% to 93% by high-dose beta-blocker therapy (>4.5 mg/kg/day propranolol). The mechanism of the beneficial effect of beta-blockers is to improve diastolic function by lengthening of diastole, reducing outflow-obstruction, and inducing a beneficial remodelling resulting in a larger left ventricular cavity, and improved stroke volume. Hypertrophic cardiomyopathy is associated with increased activity of cardiac sympathetic nerves, and infants in heart failure with hypertrophic cardiomyopathy show signs of extreme sympathetic over-activity, and require exceptionally high doses of beta-blockers to achieve effective beta-blockade as judged by 24 h Holter recordings, often 8-24 mg/kg/day of propranolol or equivalent.

Conclusion: Beta-blocker therapy is without doubt the treatment of choice for patients with heart failure caused by hypertrophic cardiomyopathy, but the dose needs to carefully titrated on an individual basis for maximum benefit, and the dose required is surprisingly large in infants with heart failure due to hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy: a review

Hypertrophic cardiomyopathy (HCM) is a global disease with cases reported in all continents, affecting people of both genders and of various racial and ethnic origins. Widely accepted as a monogenic disease caused by a mutation in 1 of 13 or more sarcomeric genes, HCM can present catastrophically with sudden cardiac death (SCD) or ventricular arrhythmias or insidiously with symptoms of heart failure. Given the velocity of progress in both the fields of heart failure and HCM, we present a review of the approach to patients with HCM, with particular attention to those with HCM and the clinical syndrome of heart failure.

Echocardiography to individualize treatment for hypertrophic cardiomyopathy

Treatments for hypertrophic cardiomyopathy are largely selected based on patient symptoms and echocardiographic findings. Moreover, all the advanced treatments for heart failure symptoms depend on such imaging for planning and monitoring response to therapy. Risk of sudden death correlates with maximum left ventricular (LV) wall thickness. Massive LV thickening of 30 mm or more is an indication for primary prevention of sudden death with an implanted defibrillator. In this review, we will underscore potential pitfalls in echocardiographic diagnosis. Also we will review, a newly appreciated pathophysiologic mechanism in obstruction dynamic systolic dysfunction due to gradient.

Pharmacological treatment options for hypertrophic cardiomyopathy: high time for evidence

Hypertrophic cardiomyopathy (HCM) is the most common genetic heart disease, affecting over one million individuals in Europe. Hypertrophic cardiomyopathy patients often require pharmacological intervention for control of symptoms, dynamic left ventricular outflow obstruction, supraventricular and ventricular arrhythmias, and microvascular ischaemia. Current treatment strategies in HCM are predicated on the empirical use of long-standing drugs, such as beta-adrenergic and calcium blockers, although with little evidence supporting their clinical benefit in this disease. In the six decades since the original description of the disease, <50 pharmacological studies enrolling little over 2000 HCM patients have been performed, the majority of which were small, non-randomized cohorts. As our understanding of the genetic basis and pathophysiology of HCM improves, the availability of transgenic and preclinical models uncovers clues to novel and promising treatment modalities. Furthermore, the number of patients identified and followed at international referral centres has grown steadily over the decades. As a result, the opportunity now exists to implement adequately designed pharmacological trials in HCM, using established as well as novel drug therapies, to potentially intervene on the complex pathophysiology of the disease and alter its natural course. Therefore, it is timely to review the available evidence for pharmacological therapy of HCM patients, highlight the most relevant gaps in knowledge, and address some of the most promising areas for future pharmacological research, in an effort to move HCM into the era of evidence-based management.

Hypertrophic Cardiomyopathy in a Young Adult with RV Aneurysm: Report of a Rare Finding and Review of the Literature

We report a case of a 22-year-old patient with a severe form of hypertrophic cardiomyopathy involving both ventricles, for which he underwent surgical treatment. Echocardiogram and magnetic resonance imaging confirmed the presence of an aneurysm in the inferior-anterior portion of the right ventricle.

Hypertrophic cardiomyopathy: infants, children, and adolescents

Hypertrophic cardiomyopathy (HCM) is characterized by inappropriate left ventricular hypertrophy (LVH) in the setting of a nondilated left ventricle. HCM is often associated with asymmetric LVH, a family history of HCM, sarcomeric genetic mutations, and an increased risk of sudden cardiac death. There is a wide clinical variability in HCM presenting during childhood and a relative lack of data on the pediatric population. This review will cover HCM presenting in infancy, childhood, and adolescence.

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.

Hypertrophic cardiomyopathy in childhood and adolescence - strategies to prevent sudden death

Clinically overt hypertrophic cardiomyopathy is the most common cause of sudden unexpected death in childhood and has significantly higher sudden death mortality in the 8- to 16-year age range than in the 17- to 30-year age range. A combination of electrocardiographic risk factors (a limb-lead ECG voltage sum >10 mV) and/or a septal wall thickness >190% of upper limit of normal for age (z-score > 3.72) defines a paediatric high-risk patient with great sensitivity. Syncope, blunted blood pressure response to exercise, non-sustained ventricular tachycardia and a malignant family history are additional risk factors. Of the medical treatments used, only beta-blocker therapy with lipophilic beta-blockers (i.e. propranolol, metoprolol or bisoprolol) have been shown to significantly reduce risk of sudden death, with doses ≥ 6 mg/kg BW in propranolol equivalents giving around a tenfold reduction in risk. Disopyramide therapy is a very useful adjunct to beta-blockers to improve prognosis in those patients that have dynamic outflow obstruction in spite of large doses of beta-blocker, and its use in patients with hypertrophic cardiomyopathy is not associated with significant pro-arrhythmia mortality. Calcium-channel blockers increase the risk of heart failure-associated death in hypertrophic cardiomyopathy (HCM) patients with severe generalized hypertrophy and should be avoided in such patients. Amiodarone does not protect against sudden death, and long-term use in children usually has to be terminated because of side effects. Therapy with internal cardioverter defibrillator implantation has high paediatric morbidity, 27% incidence of inappropriate shocks, and does not absolutely protect against mortality but is indicated as secondary prevention or in very high-risk patients.

Relationship between circulating levels of monocyte chemoattractant protein-1 and systolic dysfunction in patients with hypertrophic cardiomyopathy

BACKGROUND

Progression of hypertrophic cardiomyopathy (HCM) to left ventricular dilatation and systolic dysfunction sometimes occurs. However, the mechanism of the transition from hypertrophy to dysfunction has not been elucidated. It has been reported that circulating levels of monocyte chemoattractant protein-1 (MCP-1), which is a major factor promoting the accumulation of macrophages, are increased in patients with congestive heart failure. We measured circulating levels of MCP-1 in patients with HCM and examined whether MCP-1 was expressed in the myocardium of HCM patients. We also examined whether circulating levels of MCP-1 were correlated with left ventricular dysfunction.

METHODS

Circulating levels of MCP-1 were measured by an enzyme immunoassay in 26 patients with HCM (60+/-2 years old) and 20 control subjects (57+/-2 years old). Cardiac function was evaluated by two-dimensional echocardiography and cardiac catheterization.

RESULTS

HCM patients had significantly elevated levels of MCP-1 (HCM: 309+/-30 vs. control: 178+/-8 pg/ml, P<.001). MCP-1 levels in patients with systolic dysfunction were significantly higher than those in patients without systolic dysfunction (P<.05) and were also significantly higher than those in patients with outflow obstruction (P<.05). Immunohistochemical analysis revealed that MCP-1 was expressed in endomyocardial biopsy samples obtained from HCM patients with systolic dysfunction. Furthermore, MCP-1 levels were inversely correlated with fractional shortening (r=-.401, P<.05) and correlated with left ventricular end-diastolic pressure (r=-.579, P<.01).

CONCLUSION

These results show that MCP-1 is associated with, and might be involved in the pathogenesis of, left ventricular systolic dysfunction in patients with HCM.

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.

Pathophysiology and Treatment of Hypertrophic Cardiomyopathy

All patients with hypertrophic cardiomyopathy (HCM) should have five aspects of care addressed. An attempt should be made to detect the presence or absence of risk factors for sudden arrhythmic death. If the patient appears to be at high risk, discussion of the benefits and risks of ICD are indicated, and many such patients will be implanted. Symptoms are appraised and treated. Bacterial endocarditis prophylaxis is recommended. Patients are advised to avoid athletic competition and extremes of physical exertion. First degree family members should be screened with echocardiography and ECG.

Relationship between oxidative stress and systolic dysfunction in patients with hypertrophic cardiomyopathy

BACKGROUND

Progression of hypertrophic cardiomyopathy (HCM) to left ventricular dilatation and systolic dysfunction sometimes occurs. However, the mechanism is not known. We examined whether oxidative stress was elevated in myocardia of HCM patients and whether the levels were correlated with left ventricular dilatation and systolic dysfunction.

METHODS AND RESULTS

Endomyocardial biopsy samples obtained from the right ventricular side of the septum of 31 patients with HCM, and 10 control subjects were studied immunohistochemically for the expression of 4-hydroxy-2-nonenal (HNE)-modified protein, which is a major lipid peroxidation product. Expression of HNE-modified protein was found in all myocardial biopsy samples from patients with HCM. Expression was distinct in the cytosol of cardiomyocytes. The expression levels in patients with HCM were significantly increased compared with those in control subjects (P = .0005). The expression levels in patients with HCM were correlated with left ventricular end-diastolic diameter (r = 0.483, P = .0053) and end-systolic diameter (r = 0.500, P = .0037) determined by echocardiography. The expression levels were inversely correlated with left ventricular ejection fraction determined by left ventriculography (r = -0.640, P = .0001).

CONCLUSION

Oxidative stress was elevated in myocardia of HCM patients and the levels were correlated with left ventricular dilatation and systolic dysfunction. Oxidative stress is involved in the pathogenesis of heart failure in patients with HCM.

Multicenter study of the efficacy and safety of disopyramide in obstructive hypertrophic cardiomyopathy

OBJECTIVES

In this study we assessed the long-term efficacy and safety of disopyramide for patients with obstructive hypertrophic cardiomyopathy (HCM).

BACKGROUND

It has been reported that disopyramide may reduce left ventricular outflow gradient and improve symptoms in patients with HCM. However, long-term efficacy and safety of disopyramide has not been shown in a large cohort.

METHODS

Clinical and echocardiographic data were evaluated in 118 obstructive HCM patients treated with disopyramide at 4 HCM treatment centers. Mortality in the disopyramide-treated patients was compared with 373 obstructive HCM patients not treated with disopyramide.

RESULTS

Patients were followed with disopyramide for 3.1 +/- 2.6 years; dose 432 +/- 181 mg/day (97% also received beta-blockers). Seventy-eight patients (66%) were maintained with disopyramide without the necessity for major non-pharmacologic intervention with surgical myectomy, alcohol ablation, or pacing; outflow gradient at rest decreased from 75 +/- 33 to 40 +/- 32 mm Hg (p < 0.0001) and mean New York Heart Association functional class from 2.3 +/- 0.7 to 1.7 +/- 0.6 (p < 0.0001). Forty other patients (34%) could not be satisfactorily managed with disopyramide and required major invasive interventions because of inadequate symptom and gradient control or vagolytic side effects. All-cause annual cardiac death rate between disopyramide and non-disopyramide-treated patients did not differ significantly, 1.4% versus 2.6%/year (p = 0.07). There was also no difference in sudden death rate, 1.0%/year versus 1.8%/year (p = 0.08).

CONCLUSIONS

Two-thirds of obstructed HCM patients treated with disopyramide could be managed medically with amelioration of symptoms and about 50% reduction in subaortic gradient over >/=3 years. Disopyramide therapy does not appear to be proarrhythmic in HCM and should be considered before proceeding to surgical myectomy or alternate strategies.

Antiarrhythmic drug therapy of atrial fibrillation

In the post-AFFIRM era, treatment of AF has become the treatment of symptoms. In some patients, this will be simple rate control, but there remain a significant cohort of patients in whom rate control alone does not give acceptable symptom relief. In this group, antiarrhythmic therapy still has a role, and the AFFIRM trial indicates that this therapeutic strategy is without significant deleterious effect on mortality. The choice of antiarrhythmic agent must be individualized according to underlying cardiac pathologies and comorbidities, however. Most recently, the introduction of dofetilide has widened the therapeutic options in patients with severe heart disease, and the Canadian Trial of Atrial Fibrillation indicated the superior efficacy of amiodarone at low doses. The release/ development of newer Class III antiarrhythmic agents may offer hope for the benefits of amiodarone without the serious adverse effects with long-term therapy.

Failure of Disopyramide to Improve Right Ventricular Outflow Tract Obstruction After Living-Donor Lobar Lung Transplantation

Right ventricular (RV) outflow tract obstruction (RVOTO) is an uncommon complication of lung transplantation in patients with pulmonary hypertension (PH) and both medical management and surgical intervention are required. A 28-year-old female with primary PH was referred and because she did not respond to medical treatment, living-donor lobar lung transplantation was performed. The operation was successful, but dyspnea and exercise intolerance developed during rehabilitation and transthoracic echocardiography revealed RVOTO. Intravenous disopyramide during cardiac catheterization reduced the pressure gradient from 35 mmHg to 16 mmHg without decreasing RV systolic pressure. However, electrical and hemodynamic parameters were adversely affected by disopyramide and thus, after cardiac catheterization, administration of fluid and a low dose of atenolol was started, and her symptoms improved. Transthoracic echocardiography showed improvement in the RVOTO. This case suggests that disopyramide should be avoided for patients with RVOTO following lung transplantation and that other negative inotropic agents, such as beta-blockers, are more effective for relief of RVOTO.

A cohort study of childhood hypertrophic cardiomyopathy: improved survival following high-dose beta-adrenoceptor antagonist treatment

OBJECTIVES

The study analyzed factors, including treatment, affecting disease-related death in patients with hypertrophic cardiomyopathy (HCM) presenting in childhood.

BACKGROUND

Previous smaller studies suggest that mortality is higher in patients with HCM presenting in childhood compared with presentation in adulthood, but these studies have all originated from selected patient populations in tertiary referral centers, and reported no significant protection by treatment.

METHODS

Retrospective comparisons of mortality were done in total cohort of patients presenting to three regional centers of pediatric cardiology. There were 66 patients (25 with Noonan's syndrome) with HCM presenting at age <19 years; mean follow-up was 12.0 years.

RESULTS

Among risk factors for death were congestive heart failure (p = 0.008), large electrocardiogram voltages (Sokolow-Lyon index p = 0.0003), and degree of septal (p = 0.004) and left ventricular (p = 0.028) hypertrophy expressed as percent of 95th centile value. The only treatment that significantly reduced the risk of death on multifactorial analysis of variance was high-dose beta-adrenoceptor antagonist therapy (propranolol 5 to 23 mg/kg/day or equivalent; p = 0.0001). Nineteen out of 40 patients managed conventionally (no treatment, 0.8 to 4 mg/kg of propranolol, or verapamil) died, median survival 15.8 years, with no deaths among 26 patients on high-dose beta-blockers (p = 0.0004); survival proportions at 10 years were 0.65 (95% confidence interval 0.49-0.80) and 1.0, respectively (p = 0.0015). Survival time analysis shows better survival in the high-dose beta-blocker group compared with the "no specific therapy" group (p = 0.0009) and with the conventional-dose beta-blocker group (p = 0.002). Hazard ratio analysis suggests that high-dose beta-blocker therapy produces a 5-10-fold reduction in the risk of disease-related death.

CONCLUSIONS

High-dose beta-blocker therapy improves survival in childhood HCM.

Dynamic outflow obstruction due to the transient extensive left ventricular wall motion abnormalities caused by acute myocarditis in a patient with hypertrophic cardiomyopathy: reduction in ventricular afterload by disopyramide

A 65-year-old woman was admitted to the coronary care unit because of acute pulmonary edema. Immediate 2-dimensional and Doppler echocardiograms revealed extensive left ventricular wall motion abnormalities and left ventricular hypertrophy with extreme outflow obstruction. Although an ECG showed ST-segment elevation in the anterolateral leads, a coronary arteriogram revealed normal epicardial arteries. Heart failure was relieved after diminishing the dynamic outflow obstruction with disopyramide administration. An endomyocardial biopsy from the right ventricle on the 8th hospital day showed borderline myocarditis. Wall motion abnormalities gradually normalized within 2 weeks. It is speculated that her pulmonary edema would not have been relieved so readily without the immediate reduction in ventricular afterload by disopyramide. These clinical changes over time were observed with serial echo-Doppler examinations.

Effect of disopyramide on left ventricular pressure gradient in hypertrophic obstructive cardiomyopathy in comparison with propranolol--a case report

The effect of intravenous administration of disopyramide (total dose 100 mg, bolus 20 mg every 5 minutes) was compared with that of propranolol (total dose 10 mg, bolus 2 mg every 5 minutes) in a patient with hypertrophic obstructive cardiomyopathy. Left ventricular pressure gradient (LVPG) was assessed by continuous wave Doppler flowmetry. LVPG markedly decreased (97 to 16 mmHg), and preejection period (PEP) increased with an increase in heart rate (HR) during disopyramide injection. No changes were observed in LVPG and PEP, and a decrease occurred in HR during propranolol administration. These results indicate that disopyramide produced greater effects on the reduction of LVPG than propranolol, a negative inotropic agent, did.

Heart conduction disturbances and cardiovascular collapse after disopyramide and low-dose metoprolol in a patient with hypertrophic obstructive cardiomyopathy

Disopyramide as an antiarrhythmic can be prescribed to patients with atrial fibrillation and, owing to its negative inotropic effect, to patients with hypertrophic obstructive cardiomyopathy. It is known that in patients with cardiac conduction disturbances and heart failure, disopyramide can adversely affect heart rhythm and conduction and induce cardiovascular collapse. A patient with hypertrophic obstructive cardiomyopathy and paroxysms of atrial fibrillation is described who was treated with disopyramide and also, during the 5 days before admission, with metoprolol. In spite of normal cardiac conduction and function before disopyramide, this treatment was followed by hypotension, bradycardia, and cardiac conduction disturbances. Our case shows the potential for disopyramide, especially when combined with metoprolol, to induce grave adverse effects even in patients with normal cardiac conduction and ventricular function.

Disopyramide improves the balance between myocardial oxygen supply and demand in patients with hypertrophic obstructive cardiomyopathy

We evaluated the effects of disopyramide in terms of the balance between myocardial oxygen supply and demand in patients with hypertrophic obstructive cardiomyopathy (HOCM). The myocardial oxygen supply was evaluated by measuring coronary flow velocity and the myocardial oxygen demand was assessed by the pressure-volume area (PVA). The time velocity integral of coronary flow did not change significantly (20 +/- 6 to 21 +/- 8 cm), but the peak left ventricular pressure and left ventricular external work decreased significantly (206 +/- 44 to 157 +/- 37 mmHg, P < 0.001; 1.09 +/- 0.33 to 0.80 +/- 0.23 J/beat, P < 0.001) after disopyramide administration. From theoretical analysis using these data, we concluded that disopyramide improves the myocardial oxygen supply-demand balance in patients with HOCM.