Use of calcium-channel blocking drugs in hypertrophic cardiomyopathy

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.

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.

A complex unit for a complex disease: the HCM-Family Unit

Hypertrophic cardiomyopathy (HCM) is a group of heterogeneous disorders that are most commonly passed on in a heritable manner. It is a relatively rare disease around the globe, but due to increased rates of consanguinity within the Kingdom of Saudi Arabia, we speculate a high incidence of undiagnosed cases. The aim of this paper is to elucidate a systematic approach in dealing with HCM patients and since HCM has variable presentation, we have summarized differentials for diagnosis and how different subtypes and genes can have an impact on the clinical picture, management and prognosis. Moreover, we propose a referral multi-disciplinary team HCM-Family Unit in Saudi Arabia and an integrated role in a network between King Faisal Hospital and Inherited and Rare Cardiovascular Disease Unit-Monaldi Hospital, Italy (among the 24 excellence centers of the European Reference Network (ERN) GUARD-Heart).   Graphical Abstract.

Pharmacotherapy for the treatment of obstructive hypertrophic cardiomyopathy

Introduction: Hypertrophic cardiomyopathy (HCM) is one of the most common genetic heart diseases and represents a leading cause of sudden cardiac death as well as a prevalent cause of heart failure and stroke. HCM is characterized by a very complex pathophysiology, consisting of heterogeneous clinical manifestations and natural history. Left ventricular outflow tract (LVOT) obstruction has been considered the most knowable feature of HCM since the initial clinical descriptions of the disease.Areas covered: In this review, the authors discuss the most recent reports on the pharmacological treatment of obstructive HCM, mainly based on three different levels of intervention: control of symptoms, cardiac metabolism modulation and disease-modifying approaches, including genetic preventive therapies.Expert opinion: There are presently limited data supporting pharmacological interventions for this complex disease. However, an improved understanding of HCM pathophysiology will allow the development of novel treatment options. Two important key messages are to further study drugs with negative but limited previous results and to design new and larger trials for those molecules that have already produced positive results in HCM, especially for pressure gradients and symptoms control.

Diastolic heart failure: a concise review

The concept of “diastolic” heart failure grew out of the observation that many patients who have the symptoms and signs of heart failure had an apparently normal left ventricular (LV) ejection fraction. Thus it was assumed that since systolic function was “preserved” the problem must lie in diastole, although it is not clear by whom or when this assumption was made. Nevertheless, many guidelines followed on how to diagnose “diastolic” heart failure backed up by indicators of diastolic dysfunction derived from Doppler echoardiography. Diastolic heart failure is associated with a lower annual mortality rate of approximately 8% as compared to annual mortality of 19% in heart failure with systolic dysfunction, however, morbidity rate can be substantial. Thus, diastolic heart failure is an important clinical disorder mainly seen in the elderly patients with hypertensive heart disease. Early recognition and appropriate therapy of diastolic dysfunction is advisable to prevent further progression to diastolic heart failure and death. There is no specific therapy to improve LV diastolic function directly. Medical therapy of diastolic dysfunction is often empirical and lacks clear-cut pathophysiologic concepts. Nevertheless, there is growing evidence that calcium channel blockers, beta-blockers, ACE-inhibitors and ARB as well as nitric oxide donors can be beneficial. Treatment of the underlying disease is currently the most important therapeutic approach.

Pacing for drug-refractory or drug-intolerant hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a genetic disease with an autosomal-dominant inheritance for which negative inotropes are the most widely used initial therapies. Observational studies and small randomised trials have suggested symptomatic and functional benefits using pacing and several theories have been put forward to explain why. Pacing, although not the primary treatment for HCM, could be beneficial to patients with relative or absolute contraindications to surgery or alcohol ablation. Several randomised controlled trials comparing pacing to other therapeutic modalities have been conducted but no Cochrane-style systematic review has been done.

OBJECTIVES

To assess the effects of pacing in drug-refractory or drug-intolerant hypertrophic cardiomyopathy patients.

SEARCH METHODS

We searched the following on the 14/4/2010: CENTRAL (The Cochrane Library 2010, Issue 1), MEDLINE OVID (from 1950 onwards ), EMBASE OVID (from 1980 onwards ), Web of Science with Conference Proceedings (from 1970 onwards). No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials of either parallel or crossover design that assess the beneficial and harmful effects of pacing for hypertrophic cardiomyopathy were included. When crossover studies were identified, we considered data only from the first phase.

DATA COLLECTION AND ANALYSIS

Data from included studies were extracted onto a pre-formed data extraction paper by two authors independently. Data was then entered into Review Manager 5.1 for analysis. Risk of bias was assessed using the guidance provided in the Cochrane Handbook. For dichotomous data, relative risk was calculated; and for continuous data, the mean differences were calculated. Where appropriate data were available, meta-analysis was performed. Where meta-analysis was not possible, a narrative synthesis was written. A QUROUM flow chart was provided to show the flow of papers.

MAIN RESULTS

Five studies (reported in 10 papers) were identified. However, three of the five studies provided un-usable data. Thus the data from only two studies (reported in seven papers) with 105 participants were included for this review. There was insufficient data to compare results on all-cause mortality, cost effectiveness, exercise capacity, Quality of life and Peak O2 consumption.When comparing active pacing versus placebo pacing on exercise capacity, one study showed that exercise time decreased from (13.1 ± 4.4) minutes to (12.6 ± 4.3) minutes in the placebo group and increased from (12.1 ± 5.6) minutes to (12.9 ± 4.2) minutes in the treatment group (MD 0.30; 95% CI -1.54 to 2.14). Statistically significant data from the same study showed that left ventricular outflow tract obstruction decreased from (71 ± 32) mm Hg to (52 ± 34) mm Hg in the placebo group and from (70 ± 24) mm Hg to (33 ± 27) mm Hg in the active pacing group (MD -19.00; 95% CI -32.29 to -5.71). This study was also able to show that New York Heart Association (NYHA) functional class decreased from (2.5 ± 0.5) to (2.2 ± 0.6) in the inactive pacing group and decreased from (2.6 ± 0.5) to (1.7 ± 0.7) in the placebo group (MD -0.50; 95% CI -0.78 to -0.22).When comparing active pacing versus trancoronary ablation of septal hypertrophy (TASH), data from one study showed that NYHA functional class decreased from (3.2 ± 0.7) to (1.5 ± 0.5) in the TASH group and decreased from (3.0 ± 0.1) to (1.9 ± 0.6) in the pacemaker group. This study also showed that LV wall thickness remained unchanged in the active pacing group compared to reduction from (22 ± 4) mm to (17 ± 3) mm in the TASH group (MD 0.60; 95% CI -5.65 to 6.85) and that LV outflow tract obstruction decreased from (80 ± 35.5) mm Hg in the TASH group to (49.3 ± 37.7) mm Hg in the pacemaker group.

AUTHORS' CONCLUSIONS

Trials published to date lack information on clinically relevant end-points. Existing data is derived from small trials at high risk of bias, which concentrate on physiological measures. Their results are inconclusive. Further large and high quality trials with more appropriate outcomes are warranted.

Microvascular dysfunction, myocardial ischemia, and progression to heart failure in patients with hypertrophic cardiomyopathy

Microvascular dysfunction can be demonstrated in most patients with hypertrophic cardiomyopathy (HCM), both in the hypertrophied and nonhypertrophied myocardial walls, mostly due to intimal and medial hyperplasia of the intramural coronary arteries and subsequent lumen reduction. As a consequence, regional myocardial ischemia may be triggered by exercise, increased heart rate, or arrhythmias, in areas which are unable to increase myocardial blood flow. In patients with HCM, microvascular dysfunction leading to severe myocardial hypoperfusion during maximal hyperemia represents a strong predictor of unfavorable outcome, left ventricular remodeling with progressive wall thinning, left ventricular dysfunction, and heart failure. Accurate quantitative assessment of microvascular dysfunction and myocardial ischemia is not easily feasible in clinical practice. Although signs of inducible myocardial ischemia may be detected by electrocardiogram, echocardiography, or myocardial scintigraphy, the vasodilator response to dipyridamole by positron emission tomography is considered the method of choice for the assessment of maximal regional and global flow. Cardiac magnetic resonance provides further information, by late gadolinium enhancement (LGE), which may show areas where replacement fibrosis has occurred following microvascular ischemia and focal necrosis. LGE areas colocalize with severe regional microvascular dysfunction, are associated with increased prevalence of ventricular arrhythmias, and show more extensive distribution in the late stages of the disease, when heart failure is the dominant feature. The present review aims to provide a concise overview of the available evidence of microvascular dysfunction and ischemia eventually leading to disease progression and heart failure in HCM patients.

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.

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.

Characteristics of hypertrophic obstructive cardiomyopathy refractory to medical treatment and selection of surgical methods

BACKGROUND AND AIM OF THE STUDY

Treatment for hypertrophic obstructive cardiomyopathy (HOCM) has been reported; however, there has been no report on the characteristics of medication-responsive and -refractory hypertrophic obstructive cardiomyopathy (HOCM). Using the classification of systolic anterior movement (SAM) which has been previously reported, we tried to identify the characteristics and use them to treat HOCM appropriately.

METHODS

The clinical, echocardiographic, catheterization, and surgical data of 29 hospitalized patients with HOCM during 1980 to 1999 were analyzed retrospectively. We classified SAM in all patients by echocardiography. Nineteen patients improved with medical treatment (medical group), and 10 patients underwent surgical treatment because of ineffectiveness of medication (surgical group). We studied the relation between types of SAM and medical/surgical groups, and examined the relation between types of SAM and the surgical methods.

RESULTS

Type I SAM was significantly more frequent in the medical group, while type II SAM was more frequent in the surgical group (p = 0.047). Patients in the surgical group underwent mitral valve replacement (MVR), myectomy, or a combination of MVR and myectomy. Left ventricular outflow gradient (LVOG) of over 100 mmHg was recognized in almost all patients with type II SAM.

CONCLUSIONS

It was suggested that patients with medication-responsive HOCM tended to have type I SAM and those with refractory HOCM tended to have type II SAM. We consider that in type I SAM, if the position of the papillary muscles changed with medication or myectomy, shift of the chordae and type I SAM were reduced or disappeared. However, in type II SAM, even if the position of the papillary muscles changed, SAM did not disappear because lifting of the mitral leaflets remained. It is therefore suggested that patients with type II SAM should undergo at least MVR.

Apical hypertrophic cardiomyopathy associated with life-threatening paroxysmal atrial flutter with a slow ventricular response: a case report

A 58-year-old male patient had apical hypertrophic cardiomyopathy (HCM) associated with a life-threatening tachycardia due to atrial flutter. Following palpitation and dyspnea for 2-3 h, he became unconscious because of circulatory catastrophe, but was fully resuscitated. An electrocardiogram recorded just before the loss of consciousness revealed atrial flutter at a rate of 260 beats/min with a 2:1 ventricular response. He was diagnosed as having apical HCM based on the echocardiographic and left ventriculographic findings. Atrial stimulation at a rate of 150 pacings/min for 1 min caused a marked drop in systemic systolic blood pressure from 170 to 120 mmHg. The patient was treated with 150 mg of cibenzoline per day to prevent supraventricular tachyarrhythmias and to improve left ventricular diastolic function. At the time of the recent follow-up at 2 and a half years, he felt quite well.

Short- and long-term effects of nisoldipine on cardiac function and exercise tolerance in patients with hypertrophic cardiomyopathy

Nisoldipine is a second generation dihydropyridine calcium antagonist having characteristics of strong coronary artery dilating effect and less negative inotropic action. The purpose of this study was to evaluate the effect of nisoldipine on the cardiac function (systolic and diastolic) and the exercise tolerance, in patients with hypertrophic cardiomyopathy (HCM).

SUBJECTS

Twenty-three patients with HCM were studied.

METHODS

We measured the following indices using M-mode and pulsed wave Doppler echocardiography before and after nisoldipine therapy; left ventricular fractional shortening (LVFS), isometric relaxation time (IRT), deceleration half-time (DHT) of early diastolic mitral (E) flow, late diastolic mitral (A) flow and A/E ratio. Symptom-limited treadmill exercise test was performed. Exercise tolerance (EX) time was measured. Nisoldipine of 10 mg/day was orally administered. Same tests were repeated on day 14 and after 6 months.

RESULTS

1) Short-term effects; LVFS did not change (55.9 +/- 5.9%-->57.0 +/- 7.4%, NS) after 2 weeks. However, LV diastolic function significantly improved (IRT; 92.1 +/- 7.7 ms-->85.2 +/- 11.6 ms, p < 0.05, DHT; 70.7 +/- 16.2 ms-->63.3 +/- 3.7 ms, p < 0.05). EX time increased (8.9 +/- 2.6 min-->10.0 +/- 3.3 min, p < 0.05), 2) Long-term effects; LV diastolic function had a tendency toward improvement, but is statistically not significant (IRT; 91.1 +/- 7.6-->83.8 +/- 11.6 ms, DHT; 73.1 +/- 23.4-->61.0 +/- 11.4 ms, A/E; 1.26 +/- 0.29-->1.11 +/- 0.36) after 6 months. EX time was significantly increased (9.4 +/- 1.7--> 10.1 +/- 1.7 min, p < 0.05).

CONCLUSIONS

Nisoldipine improved LV diastolic dysfunction and exercise tolerance in patients with HCM. These effects were similar to the first generation calcium antagonists. LV diastolic dysfunction may be improved due to the reduction of intracellular calcium concentration and the relief of myocardial ischemia by strong coronary artery dilating effect. However, nisoldipine did not affect the LV systolic function because of its less negative inotropic effect.

Long-term clinical and echocardiographic follow-up after surgical correction of hypertrophic obstructive cardiomyopathy with extended myectomy and reconstruction of the subvalvular mitral apparatus

BACKGROUND

The standard surgical approach to hypertrophic obstructive cardiomyopathy (HOCM) was modified in the present series with a combination of extended myectomy with partial excision and mobilization of the papillary muscles.

METHODS AND RESULTS

Between 1979 and 1992, 58 patients (38 men and 20 women; mean age, 49 +/- 24 years) with HOCM were operated on with the use of this different technique. Their intraventricular gradients were 79 +/- 33 (+/- SD) mm Hg at rest and increased to 147 +/- 48 mm Hg with provocative maneuvers. Mild-to-moderate mitral regurgitation was present in 60% of the patients, and severe regurgitation was present in 5%. Ten patients required additional aortocoronary bypass graft surgery. Follow-up (mean, 84 months) was complete (100%). Hemodynamic improvement was documented by a significant (P < .01) decrease in left ventricular end-diastolic pressure from 19 +/- 9 to 14 +/- 6 mm Hg and reduction of basal outflow tract gradients to 5 +/- 7 mm Hg at rest and 16 +/- 24 mm Hg after provocation. Late mortality was 1.4% per patient-year, and no sudden cardiac deaths occurred during follow-up. Functional status was excellent for 84% of the patients; 8 patients were in New York Heart Association functional class III, and none were in class IV. Echocardiography revealed no outflow tract obstruction.

CONCLUSIONS

Extended myectomy and reconstruction of the subvalvular mitral apparatus in HOCM result in excellent functional improvement with relief of outflow tract obstruction. The technique can be performed safely despite its more aggressive surgical nature and allows an individualized strategy depending on the patient's extent and distribution of left ventricular hypertrophy.

Effect of verapamil on absolute myocardial blood flow in hypertrophic cardiomyopathy

Angina, despite angiographically normal coronary arteries, is a common symptom in patients with hypertrophic cardiomyopathy (HC). Verapamil has been shown to ameliorate silent myocardial perfusion defects documented by thallium-201 in patients with HC. The aim of this study was to investigate the effects of verapamil on absolute regional myocardial blood flow and flow reserve, measured by positron emission tomography (PET) in patients with HC. Echocardiography, exercise stress testing, and measurements of myocardial blood flow at rest and after administration of intravenous dipyridamole (0.56 mg/kg) were undertaken in 20 patients with HC at baseline study and 8 +/- 2 weeks after double-blind randomization to either slow-release verapamil 240 mg or placebo once daily. During treatment, resting myocardial blood flow in the interventricular septum was 0.81 +/- 0.23 versus 0.96 +/- 0.42 ml/min/g in the placebo and verapamil group, respectively (p = NS between groups and when compared with respective baseline study); resting myocardial blood flow in the left ventricular free wall was 0.67 +/- 0.17 versus 0.74 +/- 0.45 ml/min/g, respectively (p = NS). After dipyridamole infusion, myocardial blood flow in the interventricular septum was 1.42 +/- 0.52 versus 1.92 +/- 1.23 ml/min/g (p = NS between groups and when compared with respective baseline study); myocardial blood flow in the left ventricular free wall was 1.25 +/- 0.41 versus 1.68 +/- 1.37 ml/min/g, respectively (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Hypertrophic Cardiomyopathy in Athletes

In brief Hypertrophic cardiomyopathy brief (HCM) accounts for a large proportion of sudden deaths in young athletes. HCM is a complex disease with a broad clinical and morphologic spectrum. Most patients with HCM have impaired diastolic filling of the left ventricle, and about 25% have left ventricular outflow tract obstruction. Cardiac symptoms and/or signs are often present, and the condition is most effectively identified with echocardiography. Propranolol or verapamil relieves symptoms in many patients; surgery may benefit patients who have outflow obstruction associated with symptoms that persist after pharmacologic therapy. Patients with HCM should not engage in organized competitive sports or particularly strenuous exercise, although moderate recreational exercise is likely to be acceptable for such individuals.

Reversal of cardiogenic shock and severe mitral regurgitation through verapamil in hypertensive hypertrophic cardiomyopathy

A 65-year-old man with long-standing hypertension developed cardiogenic shock due to the onset of left ventricular outflow obstruction and severe mitral regurgitation after surgical repair for abdominal aortic aneurysm. This complication occurred in the early postoperative period and reversed immediately after treatment with intravenous verapamil.

A double-blind, placebo-controlled crossover trial of nadolol and verapamil in mild and moderately symptomatic hypertrophic cardiomyopathy

OBJECTIVES

The aim of this study was to determine whether therapy with a beta-adrenergic or calcium channel blocking agent can improve the functional capacity and quality of life of patients with mild or moderately symptomatic hypertrophic cardiomyopathy.

BACKGROUND

Both beta-blockers and calcium channel blockers may alleviate symptoms in hypertrophic cardiomyopathy, but previous studies have been performed in hospitalized patients or have been open studies without control subjects.

METHODS

A randomized, double-blind crossover trial of nadolol, verapamil and placebo, administered for periods of 4 weeks each, was performed in 18 patients with mild or moderately symptomatic hypertrophic cardiomyopathy (10 men, 8 women; mean age +/- SD 39 +/- 17 years). A detailed symptom assessment, bicycle exercise testing, echocardiography and Holter monitoring were performed in each period.

RESULTS

Two patients withdrew from the study owing to symptomatic sinus bradycardia during nadolol therapy. Neither drug improved maximal oxygen consumption (placebo 26 +/- 8, verapamil 23 +/- 6, nadolol 21 +/- 7 ml/kg per min; p = 0.1). Peak exercise work load was reduced by > or = 10 W in 13 patients (81%) during nadolol therapy and in 4 patients (25%) during verapamil therapy (p = 0.005, nadolol vs. verapamil). Despite the effects on exercise capacity, 13 patients (81%) preferred drug treatment (8 verapamil, 5 nadolol) over placebo (p = 0.001). Verapamil improved reported performance at work compared with nadolol (p = 0.01) and tended to improve other measures of health-related behavior and symptoms compared with nadolol and placebo.

CONCLUSIONS

In patients with mild or moderately symptomatic hypertrophic cardiomyopathy, exercise capacity was not improved by nadolol or verapamil, and individuals were more often impaired by nadolol than with verapamil. Nevertheless, many patients derived symptomatic benefit from drug therapy, especially with verapamil.

Effects on left ventricular function of pindolol added to verapamil in hypertrophic cardiomyopathy

The aim of the study was to assess the effect of adding pindolol to previously used verapamil monotherapy on left ventricular (LV) systolic and diastolic function in 20 patients with hypertrophic cardiomyopathy. Patients were initially treated with verapamil in maximal well-tolerated doses for 16 +/- 14 months; pindolol, 5 mg twice daily, was added. In a Doppler echocardiographic study all patients had altered LV diastolic filling despite verapamil therapy. The control examination, which consisted of echocardiographic study and New York Heart Association functional status classification, was performed after 20 days and repeated after > or = 6 months of follow-up. Combined pindolol and verapamil therapy caused an increase in LV diastolic filling manifested by beneficial changes of transmitral flow parameters. Also, inhibition of hypercontractile LV function expressed by reduction of LV outflow tract pressure gradient and ejection fraction was observed. New York Heart Association functional class was reduced in 13 patients. The magnitude and distribution of LV myocardial hypertrophy did not change significantly. It is concluded that pindolol and verapamil combined therapy is superior to verapamil monotherapy because of improved LV diastolic function (probably due to partial agonist activity of pindolol) and reduced hypercontractile function in patients with hypertrophic cardiomyopathy.

Effect of disopyramide on left ventricular diastolic function in patients with hypertrophic cardiomyopathy: comparison with diltiazem

Left ventricular diastolic function before and after the administration of disopyramide (100 mg) or diltiazem (30 mg) was assessed in 10 patients with nonobstructive type hypertrophic cardiomyopathy. Left ventricular diastolic function was assessed by Doppler echocardiography. The peak early (E) and late (A) diastolic flow velocities and E/A ratio (E/A) were measured. Three hours after the administration of disopyramide, blood pressure did not significantly change, but heart rate was decreased significantly (p less than 0.01). Disopyramide increased the E velocity and E/A ratio from 43.8 +/- 15.0 cm/sec to 51.3 +/- 16.1 cm/sec and from 0.71 +/- 0.20 to 1.00 +/- 0.24 (each p less than 0.01), respectively, and decreased the A velocity from 63.9 +/- 18.5 cm/sec to 52.1 +/- 14.9 cm/sec (p less than 0.01). Diltiazem increased the E velocity and E/A ratio from 42.8 +/- 12.5 cm/sec to 46.4 +/- 13.4 cm/sec (p less than 0.05) and from 0.74 +/- 0.21 to 0.96 +/- 0.28 (p less than 0.01), respectively, and decreased the A velocity from 60.6 +/- 16.4 cm/sec to 50.2 +/- 15.6 cm/sec (p less than 0.01). These results indicate that disopyramide improved left ventricular diastolic filling in hypertrophic cardiomyopathy, and its effect was similar to that of diltiazem.

Evidence for or against the efficacy of calcium channel blockers for management of hypertrophic cardiomyopathy in cats

The positive lusitropic and direct coronary vasodilating properties of the calcium channel blocking agents are beneficial therapeutic effects not provided by the beta-adrenergic blocking agents for the management of feline HCM. Data from cats studied at the University of Tennessee suggest that diltiazem more consistently alleviates clinical signs and more effectively prolongs survival in cats with HCM than either propranolol or verapamil. Orally administered diltiazem appears to have sustained beneficial effects on left ventricular filling and cardiac performance based on its ability to reduce resting heart rate, decrease blood lactate concentration, increase venous oxygen tension, improve echocardiographic parameters, and resolve radiographic abnormalities. Long-term diltiazem administration may also reverse myocardial hypertrophy in some patients. There appear to be few if any side effects of this drug. Diltiazem, therefore, provides a safe and effective approach for the management of feline HCM.

Evidence for or against the efficacy of afterload reducers for management of heart failure in dogs

Therapeutic decision making is facilitated by knowledge of the short-term and long-term hemodynamic effects of the available vasodilating agents, the nature and prevalence of their adverse side effects, and their abilities to ameliorate the signs of heart disease, to improve exercise capacity, and to prolong patient survival. This article is intended to provide the reader with a comprehensive list of the available afterload-reducing agents, to review the relevant studies of these drugs in humans and dogs with heart failure, and to provide guidelines for their use in commonly encountered clinical situations.

Effect of disopyramide on systolic and early diastolic time intervals in patients with hypertrophic cardiomyopathy

The present study clarified the effect of disopyramide on left-ventricular function in patients with hypertrophic cardiomyopathy (5 obstructive type: HOCM, 21 non-obstructive type: HNCM). The systolic and early diastolic time intervals were assessed 3 hours after a single oral administration of 100-mg disopyramide. The following parameters were evaluated at rest and after administration of disopyramide: 1) left-ventricular ejection time index (LVETI), 2) pre-ejection period index (PEPI), 3) the interval from aortic component of the second heart sound to mitral valve opening (IIA-MVO), and 4) the interval from MVO to O point of apexcardiogram (MVO-O). LVETI in HNCM did not change after disopyramide but that in HOCM was significantly shortened (P less than .05). PEPI in both HOCM and HNCM was significantly prolonged after administration of disopyramide. IIA-MVO time in both HOCM and HNCM was not influenced by disopyramide. MVO-O time in both HOCM and HNCM was significantly shortened after disopyramide. These results suggest that 1) shortening of LVETI in HOCM after disopyramide seemed to be due to the decrease in pressure gradient, 2) PEPI prolongation after disopyramide reflected the decrease in myocardial contractility, and 3) shortening of MVO-O time after disopyramide indicated the improvement of left-ventricular filling. The authors conclude that disopyramide may be an important new therapeutic agent in the treatment of patients with hypertrophic cardiomyopathy.

Dynamic changes in left ventricular outflow tract flow velocities after amyl nitrite inhalation in hypertrophic cardiomyopathy

Doppler echocardiography was performed in 21 patients with hypertrophic cardiomyopathy (HC), in nine patients with no evidence of left ventricular (LV) hypertrophy by two-dimensional echocardiography, and in five patients with systemic hypertension and concentric LV hypertrophy. The LV outflow tract (LVOT) peak velocity was recorded by continuous wave Doppler technique at rest and after amyl nitrite inhalation. The LVOT pressure gradient was calculated by the modified Bernoulli equation. A significant increase in heart rate and a drop in systolic blood pressure were observed in all patients after amyl nitrite inhalation; no adverse effects were encountered. The peak LVOT velocity and pressure gradient increased significantly after provocation in all patients, but the increase was much more pronounced in patients with HC (peak LVOT velocity increased from 2.2 +/- 0.8 to 4.3 +/- 1.0 m/sec and peak gradient increased from 22 +/- 17 to 78 +/- 36 mm Hg). The Doppler spectral signal in patients with HC demonstrated a characteristic contour, with peak velocity occurring in late systole. However, the observed increase in LVOT peak velocity was not statistically different between treated (with beta-blockers and calcium blockers) and untreated patients with HC. We conclude that LVOT peak velocity and pressure gradients in patients with HC can be readily assessed by Doppler echocardiography both at rest and after amyl nitrite inhalation. The dynamic changes in LVOT velocity induced by this provocation have certain characteristic features in obstructive HC but appear to be independent of the medical regimen used, at least in the dosages tested in our study.

Long-term follow-up of medical versus surgical therapy for hypertrophic cardiomyopathy: a retrospective study

In a retrospective analysis 139 patients with hypertrophic cardiomyopathy were followed up for 8.9 years (range 1 to 28 years). Patients were divided into two groups: Group 1 consisted of 60 patients with medical therapy and Group 2 of 79 patients with surgical therapy (septal myectomy). Groups 1 and 2 were subdivided according to the medical treatment. Group 1a received propranolol, 160 mg/day (n = 20); Group 1b verapamil, 360 mg/day (n = 18); and Group 1c, no therapy (n = 22). Group 2a received verapamil, 120 to 360 mg/day, after septal myectomy (n = 17) and Group 2b had no medical therapy after surgery (n = 62). In Group 1, 19 patients died (annual mortality rate 3.6%) and in Group 2, 17 patients died (mortality rate 2.4%, p = NS). Of the patients who died, approximately one half to two thirds in both Groups 1 and 2 died suddenly and the other one half to one third died because of congestive heart failure. The 10 year cumulative survival rate was 67% in Group 1, significantly smaller than that in Group 2 (84%, p less than 0.05). In the subgroups, the 10 year survival rate was 67% in Group 1a, 80% in 1b (p less than 0.05 versus 1a) and 65% in 1c (p less than 0.05 versus 1b). The 10 year survival rate was 100% in Group 2a (p less than 0.05 versus 1a, 1b, 1c) and 78% in Group 2b (p less than 0.05 versus 2a). It is concluded that cumulative survival rate is significantly better in surgically than in medically treated patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac determinants of regression of left ventricular hypertrophy in essential hypertension with antihypertensive treatment

To study the cardiac determinants of regression of left ventricular hypertrophy in hypertension, left ventricular mass, fractional shortening and end-systolic wall stress were measured echocardiographically in 36 patients with essential hypertension and left ventricular hypertrophy. The patients were classified into two groups. Group I consisted of 15 patients with subnormal end-systolic wall stress, and Group II consisted of 21 patients with normal end-systolic wall stress. There were no significant differences between groups in systolic or diastolic blood pressure. After treatment for 4.4 +/- 1.7 years, echocardiographic studies were repeated. There were no significant differences between groups in the duration of the follow-up period and the kinds of antihypertensive drugs. After treatment, blood pressure decreased significantly in both groups (p less than 0.001 for both), with no significant difference between groups. Left ventricular mass increased significantly in Group I (from 331 +/- 7 to 363 +/- 24 g, mean +/- SEM, p less than 0.05), whereas it decreased significantly in Group II (from 318 +/- 16 to 268 +/- 17 g, p less than 0.001). Myocardial contractility (the relation between end-systolic wall stress and fractional shortening) remained almost the same as before treatment. In conclusion, in patients with hypertensive ventricular hypertrophy with subnormal end-systolic wall stress (inappropriate hypertrophy, probably induced by a neurohumoral factor), a decrease in blood pressure with antihypertensive treatment does not lead to regression of left ventricular hypertrophy, but rather to an increase in left ventricular mass.(ABSTRACT TRUNCATED AT 250 WORDS)

Verapamil. An updated review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in hypertension

Although verapamil is a well-established treatment for angina, cardiac arrhythmias and cardiomyopathies, this review reflects current interest in calcium antagonists as anti-hypertensive agents by focusing on the role of verapamil in hypertension. Verapamil is a phenylalkylamine derivative which antagonises calcium influx through the slow channels of vascular smooth muscle and cardiac cell membranes. By reducing intracellular free calcium concentrations, verapamil causes coronary and peripheral vasodilation and depresses myocardial contractility and electrical activity in the atrioventricular and sinoatrial nodes. Verapamil is well suited for the management of essential hypertension since it produces generalised systemic vasodilation resulting in a marked reduction in systemic vascular resistance and, consequently, blood pressure. Evidence from clinical studies supports the role of oral verapamil as an effective and well-tolerated first-line treatment for the management of patients with mild to moderate essential hypertension. Clinical studies have shown that verapamil is more effective the higher the pretreatment blood pressure and some authors have found a more pronounced antihypertensive effect in older patients or in patients with low plasma renin activity. Sustained release verapamil formulations are available for oral administration which, as a single daily dose, are as effective in lowering blood pressure over 24 hours as equivalent doses of conventional verapamil formulations given 3 times daily. As a first-line antihypertensive agent, oral verapamil is equivalent to several other calcium antagonists, beta-blockers, diuretics, angiotensin-converting enzyme (ACE) inhibitors and other vasodilators, and is not associated with many of the common adverse effects of these treatments. Verapamil may be preferred as an alternative first-line antihypertensive treatment to diuretics in elderly patients because it has similar efficacy in these patients without causing the adverse effects commonly linked with diuretic treatment. Furthermore, because verapamil does not cause bronchoconstriction, it may be used in preference to beta-blockers in patients with asthma or chronic obstructive airway disease. Reflex tachycardia, orthostatic hypotension or development of tolerance is not evident following verapamil administration. As a second- or third-line treatment for patients refractory to established antihypertensive regimens, verapamil produces marked blood pressure reductions when combined with diuretics and/or ACE inhibitors, beta-blockers and vasodilators such as prazosin.(ABSTRACT TRUNCATED AT 400 WORDS)

Verapamil prevents silent myocardial perfusion abnormalities during exercise in asymptomatic patients with hypertrophic cardiomyopathy

Recent studies indicate that reversible 201Tl perfusion defects, compatible with silent myocardial ischemia, commonly develop during exercise in asymptomatic or mildly symptomatic patients with hypertrophic cardiomyopathy (HCM). To determine whether this represents a dynamic process that may be modified favorably by medical therapy, we studied 29 asymptomatic or minimally symptomatic patients with HCM, aged 12-55 years (mean, 28), with exercise 201Tl emission computed tomography under control conditions and again after 1 week of oral verapamil (mean dosage, 453 mg/day). Treadmill time increased slightly during verapamil (21.0 +/- 3.6 to 21.9 +/- 2.7 minutes, p less than 0.005), but peak heart rate-blood pressure product was unchanged (26.3 +/- 6.0 X 10(3) compared with 25.0 +/- 6.4 X 10(3). Two midventricular short-axis images per study were divided into five regions each, and each of these 10 regions was then analyzed on a 0-2 scale by three observers blinded with regard to the patients' therapy. Average regional scores of 1.5 or less were considered to represent perfusion defects, and a change in regional score of 0.5 or more was considered to constitute a significant change. During control studies, 15 patients (52%) developed perfusion defects with exercise (average, 3.7 regions per patient). In 14 of these patients, all perfusion defects completely reversed after 3 hours of rest; one patient had fixed defects. After administration of verapamil, exercise perfusion scores improved in 10 of the 14 patients (71%) with reversible defects; there was overall improvement in 34 of 50 (68%) regions with initially reversible perfusion defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary flow reserve and diastolic dysfunction in hypertrophic cardiomyopathy

We studied 14 patients with hypertrophic cardiomyopathy during and after atrial pacing by simultaneous registration of left ventricular high fidelity pressure measurements and M-mode echocardiography together with great cardiac vein flow measured by thermodilution. Heart rate rose from 75 +/- 18 to 142 +/- 14 beats/minute with an increase of 93 +/- 30 to 127 +/- 46 milliliters/minute of great cardiac vein flow (increase of flow/beat: 0.8 versus 1.5 milliliters/beat in normal individuals; P less than 0.05). In addition, diastolic hemodynamic parameters (such as left ventricular end-diastolic pressure, T1 (time constant of relaxation) (of first 40 milliseconds) and T2 (of second 40 milliseconds) and LVdP/dt-) changed from, respectively, 27.4 +/- 7.1 to 24.0 +/- 10.3 mm Hg; (NS), 67.3 +/- 16.1 to 65.7 +/- 22.2 liters/second; (NS) 68.6 +/- 36.9 to 52.9 +/- 19.4 (P less than 0.05), and 1592 +/- 75 to 1302 +/- 48 mm Hg/sec; P less than 0.05. Left ventricular end-diastolic dimensions decreased whereas end-diastolic wall thickness increased from, respectively, 37 +/- 3 to 34 +/- 4 millimeters; (P less than 0.05) and 14 +/- 2 to 17 +/- 1 millimeters (P less than 0.05). Eleven of the 14 patients experienced angina pectoris concomitant with ST-T depression of 1 millimeter or more on the electro-cardiogram. No correlations were found between great cardiac venous flow and hemodynamically or ultrasonically derived diastolic parameters of left ventricular function.

Hypertrophic cardiomyopathy: current views on etiology, pathophysiology, and management

Hypertrophic cardiomyopathy (HCM) is a primary myocardial disease of unknown cause that is characterized by a hypertrophied, nondilated, hypercontractile left ventricle. Its etiology and pathogenesis remain undefined but the three principal factors implicated are a genetic predisposition, a hypersensitivity to catecholamines, and an abnormal calcium metabolism. The hypertrophy typically involves the intraventricular septum to varying degrees, but may also involve the apex or free wall and even be concentric. The disease occurs in either an obstructive or a nonobstructive form depending on whether an intraventricular pressure gradient can be demonstrated at rest or on provocation. The gradient and obstruction to outflow is usually seen in patients with asymmetric septal hypertrophy (ASH) and anterior motion of the mitral valve during systole (SAM). Abnormal left ventricular diastolic function characterized by inadequate filling and impaired relaxation has been shown to be very important in both the obstructive and nonobstructive forms of the disease. In addition, inadequate coronary vasodilator reserve as a result of small vessel disease, microvascular spasm, and/or low capillary density per unit myocardial mass has been implicated as an important cause of ischemia in patients without coronary artery disease. HCM is a disease of young adulthood with relatively slow progression; young patients are often asymptomatic, whereas older patients are more limited by dyspnea, angina, dizziness, or syncope. Supraventricular tachyarrhythmias occur in 30% of patients, and high-grade ventricular arrhythmias occur in over 75%. The annual mortality is 3-5%. The common mode of demise is sudden cardiac death. Therefore, the primary objectives of treatment are the amelioration of symptoms, the control of arrhythmias, and the prevention of sudden death. Beta-adrenoreceptor blocking agents decrease myocardial contractility and oxygen demands and increase ventricular volume; therefore, they are most useful in patients with the obstructive form of HCM. Calcium channel antagonists enhance left ventricular relaxation, relieve microvascular spasm, and improve coronary filling and therefore are the agents of choice in patients with diastolic dysfunction. The ability of the calcium channel antagonists to decrease contractility makes them valuable in patients with obstructive HCM. Arterial vasodilators, diuretics, nitrates, and inotropic agents should be avoided because they can increase the intraventricular gradient. Myomyectomy is reserved for those patients with the obstructive form of HCM whose symptoms are refractory to medical therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Calcium modulators: future agents, future uses

The calcium modulators have been a significant therapeutic advancement for the treatment of angina. Structural analogs of verapamil and nifedipine have been synthesized, as have structurally unique compounds. As the role of calcium in body processes is further elucidated, the efficacy of the calcium modulators is being evaluated for numerous disorders. It is anticipated that the newly synthesized compounds will have specificity toward particular body processes, thus providing efficacy with minimal side effects.

Calcium channel blockers and cardiac surgery

Calcium channel blockers have an important role in the pharmacotherapy of cardiovascular disorders. These agents act by inhibiting the slow inward current into excitable cells, exert direct negative inotropic, chronotropic, and dromotropic activity, and are potent vasodilators. These direct effects are modified by reflex autonomic stimulation and by pathologic states. Serious adverse effects of the calcium channel blockers are most frequently observed in patients with ventricular dysfunction, conduction system disease, or concomitant beta blockade. Calcium channel blockers are indicated in the treatment of angina pectoris, supraventricular arrhythmias, and hypertension. The use of these agents in patients with hypertrophic cardiomyopathy, congestive heart failure, and pulmonary hypertension is investigational. The calcium channel blockers are gaining increased importance in the management of patients undergoing cardiac surgery. Verapamil is indicated for the treatment of post-cardiac-surgical atrial flutter and fibrillation; however, the calcium antagonists are not effective as prophylaxis against postoperative supraventricular arrhythmias. Laboratory studies have shown that drug interactions exist between calcium channel blockers and inhalational anesthetics and nondepolarizing neuromuscular blocking agents; clinical studies have demonstrated that these interactions are rarely significant. Perioperative coronary spasm can be effectively treated with the calcium channel blockers. The timing of calcium antagonist withdrawal prior to surgery is controversial, but continuation of therapy until surgery is usually safe. The clinical significance of platelet function inhibition by the calcium antagonists is unknown. Protection of ischemic myocardium by calcium channel blockers has been demonstrated. Important interactions between the calcium antagonists, hypothermia, and the ionic constituents of cardioplegia require further study before the role of these agents as adjuncts to clinical cardioplegia is defined. Expanded indications and the introduction of new calcium channel blockers will result in increased use of these agents in the future.

The mechanism of action of calcium antagonists relative to their clinical applications

As a class of therapeutic agents calcium antagonists have attracted increasing attention in recent years. Their major indications have been in the treatment of ischaemic myocardial syndromes, certain cardiac arrhythmias, hypertension, obstructive cardiomyopathies, and a number of lesser clinical disorders in which their role is less clearly defined. With the widening spectrum of therapeutic utility and an increasing plethora of newer agents under development, it is of importance to relate the overall pharmacodynamics of individual agents to their clinical effects. Calcium antagonists have a variable specificity for cardiac and peripheral activity. Based on such activity, it is useful to construct a classification of these compounds, new and old, into four categories. Type I agents, typified by verapamil and its congeners (tiapamil and gallopamil) and diltiazem, prolong AV nodal conduction and refractoriness with little effect on ventricular or atrial refractory period. These actions account for their direct antiarrhythmic properties. Type II agents include nifedipine and other dihydropyridines. In vivo, these agents are devoid of electrophysiologic effects in usual doses. They are potent peripheral vasodilators with some selectivity of action for different vascular beds; their overall haemodynamic effects are dominated by this peripheral vasodilatation and reflex augmentation of sympathetic reflexes. Type III agents include flunarizine and cinnarizine (piperazine derivatives), which, in vitro and in vivo, are potent dilators of peripheral vessels, with no corresponding calcium-blocking actions in the heart. Type IV agents are agents with a broader pharmacologic profile (perhexiline, lidoflazine and bepridil); they block calcium fluxes in the heart, in the peripheral vessels, or both. They may inhibit the fast channel in the heart and have other electrophysiologic actions. A clear understanding of the varied pharmacologic properties of the different classes of calcium antagonists is likely to provide a rational basis for the use of these agents in clinical therapeutics.

Effects of sublingual nifedipine on hemodynamics and systolic and diastolic function in patients with hypertrophic cardiomyopathy

The hemodynamic effects of sublingual nifedipine were examined in 36 patients with hypertrophic cardiomyopathy. Twenty-one patients were initially given 20 mg and 15 patients were given 10 mg of the drug; 30 min after this first dose 26 patients received 10 mg and one patient 20 mg as a second dose. Hemodynamic findings in patients who received different doses of the drug were similar. Peak effects included an increase in heart rate from 79 +/- 12 to 91 +/- 14 (mean +/- 1 SD) beats/min (p less than .01), and a decrease in mean blood pressure from 89 +/- 12 to 77 +/- 10 mm Hg (p less than .01). Cardiac index increased after nifedipine (2.8 +/- 0.6 to 3.3 +/- 0.8 liters/min/m2; p less than .01); stroke volume index, however, did not change (36 +/- 7 to 36 +/- 8 ml/beat/m2; NS). Peripheral vascular resistance index fell significantly from 822 +/- 261 to 610 +/- 197 dynes X sec X cm-5 (p less than .01). Overall, left ventricular outflow tract gradient (LVOTG) did not change in patients with significant (greater than or equal to 30 mm Hg) basal LVOTG (75 +/- 22 to 83 +/- 22 mm Hg; NS), but it increased significantly in those six patients in whom peripheral vascular resistance fell by 25% or more (73 +/- 28 to 99 +/- 22 mm Hg; p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)