Beneficial effects of long-term diltiazem treatment in dilated cardiomyopathy

Safety and Efficacy of Nondihydropyridine Calcium Channel Blockers for Acute Rate Control in Atrial Fibrillation with Rapid Ventricular Response and Comorbid Heart Failure with Reduced Ejection Fraction

The use of nondihydropyridine calcium channel blockers (NDCCBs) to achieve rate control in atrial fibrillation with the rapid ventricular rate (AF RVR) is not recommended in patients with comorbid heart failure with reduced ejection fraction (HFrEF) due to the concern for further blunting of contractility. However, these recommendations are extrapolated from data examining chronic NDCCB use in HFrEF patients, and comorbid AF was not analyzed. These recommendations also do not cite the hemodynamic effects or clinical outcomes of NDCCBs for acute rate control in HFrEF patients with AF RVR. It is our goal to open the discussion concerning the hemodynamic effects and safety profile of NDCCBs for acute rate control in this specific patient population. In the acute setting of AF RVR and HFrEF, there is a paucity of low-quality data on the safety and hemodynamic effects of NDCCBs, with mixed results. There has not been a clear signal toward adverse outcomes with NDCCBs, particularly for diltiazem. Data in this scenario is similarly limited for beta blockers, which provide the additional hemodynamic effect of the neurohormonal blockade, which provides a long-term mortality benefit to HFrEF patients. We support the cautious use of beta blockers as first-line therapy in clinical settings where an acute rate control strategy for AF RVR is warranted. We also support diltiazem as a reasonable second-line option, though the relative paucity of data calls for further research to validate this conclusion. Verapamil in this setting should be avoided until more data are available.

Coronary Artery Spasm-Related Heart Failure Syndrome: Literature Review

Although heart failure (HF) is a clinical syndrome that becomes worse over time, certain cases can be reversed with appropriate treatments. While coronary artery spasm (CAS) is still underappreciated and may be misdiagnosed, ischemia due to coronary artery disease and CAS is becoming the single most frequent cause of HF worldwide. CAS could lead to syncope, HF, arrhythmias, and myocardial ischemic syndromes such as asymptomatic ischemia, rest and/or effort angina, myocardial infarction, and sudden death. Albeit the clinical significance of asymptomatic CAS has been undervalued, affected individuals compared with those with classic Heberden's angina pectoris are at higher risk of syncope, life-threatening arrhythmias, and sudden death. As a result, a prompt diagnosis implements appropriate treatment strategies, which have significant life-changing consequences to prevent CAS-related complications, such as HF. Although an accurate diagnosis depends mainly on coronary angiography and provocative testing, clinical characteristics may help decision-making. Because the majority of CAS-related HF (CASHF) patients present with less severe phenotypes than overt HF, it underscores the importance of understanding risk factors correlated with CAS to prevent the future burden of HF. This narrative literature review summarises and discusses separately the epidemiology, clinical features, pathophysiology, and management of patients with CASHF.

Myocardial Ischemic Syndromes, Heart Failure Syndromes, Electrocardiographic Abnormalities, Arrhythmic Syndromes and Angiographic Diagnosis of Coronary Artery Spasm: Literature Review

In coronary artery spasm (CAS), an excess coronary vasoconstriction causing total or subtotal vessel occlusion could lead to syncope, heart failure syndromes, arrhythmic syndromes, and myocardial ischemic syndromes including asymptomatic myocardial ischemia, stable and unstable angina, acute myocardial infarction, and sudden cardiac death. Although the clinical significance of CAS has been underrated because of the frequent absence of symptoms, affected patients appear to be at higher risk of syncope, serious arrhythmias, and sudden death than those with classic Heberden's angina pectoris. Therefore, a prompt diagnosis has important therapeutic implications, and is needed to avoid CAS-related complications. While a definitive diagnosis is based mainly on coronary angiography and provocative testing, clinical features may help guide decision-making. We perform a literature review to assess the past and current state of knowledge regarding the clinical features, electrocardiographic abnormalities and angiographic diagnosis of CAS, while a discussion of mechanisms is beyond the scope of this review.

Heart failure in which coronary spasms played an important role

A 69-year-old woman was admitted for further examinations and treatment of chest pain. Emergency cardiac catheterization showed no significant stenosis on coronary angiograms; however, diffuse wall hypokinesis was observed on a left ventriculogram. After treating the patient's heart failure, cardiac catheterization was performed again. A spasm provocation test showed coronary spasms of the right and left coronary arteries. A right ventricular endomyocardial biopsy revealed denaturation and fibrosis of the myocardium under the endocardium, thus suggesting the presence of myocardial ischemia. This case highlights coronary spasms as a cause of heart failure.

Diltiazem to treat sinus tachycardia in critically ill patients: a four-year experience

OBJECTIVES

To determine whether an intravenous infusion of the calcium channel blocker diltiazem was effective and safe in treating sinus tachycardia in critically ill adult patients with contraindications to beta-blockers or in whom beta-blockers were ineffective.

DESIGN

Retrospective chart review.

SETTING

University medical center.

PATIENTS

The records of 171 surgical intensive care unit patients with sinus tachycardia treated with intravenous diltiazem were evaluated.

INTERVENTIONS

In all patients with sinus tachycardia (heart rate >100 beats/min), heart rate control with intravenous diltiazem was attempted after adequate intravascular volume expansion, pain, and anxiety control. In all patients, beta-blockade either was contraindicated or (in 7%) had failed. Intravenous diltiazem was administered as a slow 10-mg bolus dose (0.1-0.2 mg/kg ideal body weight), and then an infusion was started at 5 or 10 mg/hr and increased up to 30 mg/hr, as needed, to decrease heart rate to <100 beats/min. Variables retrospectively collected included demographic data, preinfusion blood pressure, mean arterial pressure, heart rate, and preinfusion pressure-rate quotients (pressure-rate quotient = mean arterial pressure / heart rate). Intravenous bolus dose, when given, and diltiazem infusion rate and time necessary to achieve the target heart rate also were recorded. The lowest heart rate recorded within 24 hrs from the initiation of the infusion and the time necessary to achieve the lowest heart rate after beginning the infusion were recorded.

MEASUREMENTS AND RESULTS

Of 171 patients studied, 97 (56%) were classified as responders. Multiple linear regression suggested that response could be predicted by age, pressure-rate quotients, baseline mean arterial pressure, and central nervous system failure. In the responders, a heart rate <100 beats/min was achieved in an average of 2 hrs, at a mean diltiazem infusion of 13.3 mg/hr. The lowest rate reached by the responders in a 24-hr period averaged 86 beats/min and was achieved in 4.8 hrs with a mean infusion rate of 14.8 mg/hr. Both target and lowest rate values were statistically different from baseline heart rate.

CONCLUSION

Diltiazem was effective in achieving short-term control of heart rate in 56% of the patients, virtually without adverse effects, where beta-blockade was contraindicated or ineffective.

Diffuse and severe left ventricular dysfunction induced by epicardial coronary artery spasm

Endothelial dysfunction and effectiveness of treatment of calcium antagonists are suggestive of coronary artery spasm as an underlying disorder in dilated cardiomyopathy (DCM). The aim of this study is to determine whether or not the epicardial coronary artery spasm can induce severe cardiac dysfunction like DCM. Thirty-four consecutive patients with angiographically normal coronary arteries and diffuse left ventricular hypokinesis whose causes had been unknown underwent acetylcholine provocation test and left ventricular biopsy. Eight patients were excluded according to the clinical and laboratory data and biopsy findings suggesting myocarditis or other systemic diseases. According to the results of the acetylcholine provocation test, 17 patients were finally diagnosed as having DCM, and nine patients (35% of the study patients), who had acetylcholine-induced diffuse and multivessel coronary spasm, were diagnosed as having DCM-like vasospastic angina pectoris (VSA). Clinical and cardiac catheterization data including hemodynamics and biopsy findings were similar between the two groups except that left ventricular end-systolic volume was significantly greater in DCM than in DCM-like VSA. After the acetylcholine provocation test, DCM patients received both a beta blocker and an angiotensin-converting enzyme inhibitor, and DCM-like VSA patients received antianginal drugs. In echocardiographic findings at predischarge and those after 6-month drug treatment, both DCM-lke VSA and DCM showed significant reduction in end-diastolic and end-systolic diameters and significant increase in fractional shortening and ejection fraction, whereas changes in ejection fraction and fractional shortening were significantly greater in DCM-like VSA than those in DCM. Epicardial coronary artery spasm can induce diffuse and severe left ventricular dysfunction like DCM in VSA. Although antianginal drugs markedly improve left ventricular function of these patients, only the acetylcholine provocation test can identify DCM-like VSA.

Calcium channel blockers in cardiac failure

Congestive cardiac failure is an increasingly prevalent syndrome associated with a high morbidity and mortality. The role of calcium channel blockers in the treatment of heart failure is unclear. The potential benefits of these agents derive not only from their vasodilator properties, but also from anti-ischemic effects, beneficial effects on endothelial function and the development of atherosclerosis, and favorable effects on calcium cycling at a molecular level. Pitted against this array of potential benefits are direct negative inotropic effects and the potential for neuroendocrine activation. Treatment with short-acting dihydropyridine agents has not resulted in long-term clinical benefits in patients with cardiac failure. Diltiazem may be beneficial in patients with nonischemic heart failure, and verapamil has a neutral effect in cardiac failure, although it may have a role in combination with ace inhibition. To date, amlodipine has been associated with the most promising results, with evidence of a mortality benefit in nonischemic heart failure. Mibefradil is of no benefit in the management of heart failure, although the trend toward increased mortality in the treatment arm of the Mortality Assessment in Congestive Heart Failure (MACH)-1 trial may have been due to drug interactions. The potential role of calcium blockers in diastolic dysfunction and in combination with ace-inhibition requires further study.

Interventional study of diltiazem in dilated cardiomyopathy: a report of multiple centre clinical trial in China. Chinese Cooperative Group of Diltiazem Intervention Trial in Dilated Cardiomyopathy

The aim of this study was to determine the interventional effects of diltiazem on autoantibody mediated myocardial damage in dilated cardiomyopathy (DCM). 221 patients with DCM in 16 hospitals were included in the multiple centre clinical trial from January 1995 to November 1996, using the diltiazem or placebo based on the background therapy for heart failure. Patients were randomly divided into groups for a single blind trial, followed by observation for an average of 7.4 months. After treatment, the heart function of 84% of patients in the diltiazem group recovered to grade I or II, but this occurred for 64% of patients in the placebo group. Heart-thorax ratio was decreased from 0.59+/-0.07 to 0.56+/-0.07 and the left ventricular end-diastolic dimension (LVEDd) from 65.40+/-8.60 mm to 61.12+/-9.86 mm, the left ventricular ejection fraction (EF) was increased from 35.75+/-10.78% to 42.52%+/-11.41% (P<0.01) in the diltiazem group (n=114). The above parameters were not significantly changed in the placebo group (n=107). Mortality was 3.5% in the diltiazem group and 11.2% in the placebo group (P<0.05). Further analysis also shows that LVEDd were reduced and EF were obviously elevated in patients with DCM of LVEDd <70 mm, but the above parameters weren't improved in patients of LVEDd >70 mm. The study suggests that diltiazem is safe and effective in the treatment of DCM, the action mechanism might be intervention in antibody-mediated myocardial damage and protection of myocardium. Diltiazem is suitable for the treatment of the early stage in DCM.

Beneficial effects of amlodipine in a murine model of congestive heart failure induced by viral myocarditis. A possible mechanism through inhibition of nitric oxide production

BACKGROUND

Although calcium channel blockers have not been shown to be beneficial for the treatment of patients with heart failure, a recent clinical trial demonstrated a favorable effect of amlodipine on the survival of patients with heart failure resulting from nonischemic dilated cardiomyopathy. We investigated the effects of amlodipine on a murine model of congestive heart failure induced by the M variant of encephalomyocarditis virus (EMCV).

METHODS AND RESULTS

Four-week-old male DBA/2 mice were inoculated with EMCV and administered amlodipine, diltiazem, or vehicle PO for 2 weeks. The heart weight-to-body weight ratio and the histopathological grades of myocardial lesions were significantly lower and survival was significantly increased in the amlodipine-treated group (P < .01, P < .05, and P < .05, respectively) than in the control group. In vitro, amlodipine added to murine J774A.1 macrophages concomitant with EMCV inhibited nitrite formation in a concentration-dependent manner, but diltiazem did not. Furthermore, NG-monomethyl-L-arginine, an inhibitor of NO synthesis, decreased myocardial lesions significantly in this murine model. Immunohistochemistry revealed that the number of cells stained with antibody against an inducible NO synthase decreased significantly in the amlodipine-treated group compared with that in the control group (P < .01).

CONCLUSIONS

Amlodipine appears to have a protective effect against myocardial injury in this animal model of congestive heart failure. The therapeutic effect of amlodipine may be in part resulting from inhibition of overproduction of NO.

Comparison of the therapeutic effects of the beta-blocking agent bisoprolol and the calcium-blocking agent diltiazem in patients with heart failure due to dilated cardiomyopathy

Beta-blocking agents reduce mortality and improve symptoms in patients with dilated cardiomyopathy (DCM). There have been reports that diltiazem, a calcium-blocking agent, is also effective in such patients. We prospectively compared the effects of the beta-blocking agent bisoprolol with those of the calcium-blocking agent diltiazem in 18 patients (11 males and 7 females, age 14 to 68) with DCM. The 18 patients, (10 in New York Heart Association functional class III and 8 in class IV) were randomly assigned to 2 groups. Bisoprolol was administered as the first drug in 10 patients and diltiazem was administered in 8. Cross-over to bisoprolol was also performed in 3 patients. At the end of the study, among the 13 patients who had been given bisoprolol, 9 showed a good response (efficacy rate: 69%). In contrast, only 3 of the 8 patients who received diltiazem showed a good response (efficacy rate: 37.5%). Among the patients in NYHA class III, all 7 (100%) who were treated with bisoprolol responded but only 2 of the 4 (50%) treated with diltiazem responded (p < 0.05). Among the patients in class IV, 2 of 6 (33%) responded to bisoprolol and 1 of 4 (25%) responded to diltiazem (not significant). These results suggest that diltiazem, like bisoprolol, has a beneficial effect in patients with DCM, with a greater effect in class III patients. However, we conclude that diltiazem should usually be used as a second choice to improve heart failure in DCM, and as the first medication only in those with contraindications to beta-blocking agents.

Heart Frequency Modulation: An Emerging Therapeutic Modality in the Failing Heart

Understanding of the importance of the role of compensatoty mechanisms in heart failure has been translated into therapeutic options which can improve cardiac function, favorably alter disease progression, and improve survival. Sinus tachycardia in heart failure results from neurohormonal activation, which reduces ventricular filling time and thus further increases atrial pressure and venous congestion. It may also cause myocardial ischemia, leading to progressive ventricular dysfunction. In this review, the role of heart frequency modulators in heart failure is discussed.

Diltiazem improves cardiac function and exercise capacity in patients with idiopathic dilated cardiomyopathy. Results of the Diltiazem in Dilated Cardiomyopathy Trial

BACKGROUND

Evidence is arising that calcium antagonists in idiopathic dilated cardiomyopathy (IDC) may have beneficial effects on virus-induced cardiopathology, alcohol toxicity, micro-circulatory disorders, and impaired calcium cycling, all possibly involved in the pathogenesis of the disease. Thus, the effect of adjunct diltiazem (60 to 90 mg TID) on standard treatment was investigated.

METHODS AND RESULTS

The Diltiazem in Dilated Cardiomyopathy (DiDi) trial was a randomized, double-blind, placebo-controlled, multicenter trial of 186 patients (92 receiving diltiazem, 94 receiving placebo) with IDC diagnosed by coronary angiography, catheterization of the left side of the heart, and a left ventricular ejection fraction of < 0.50 (mean, 0.34 +/- 0.11). The effect of adjunct diltiazem treatment on transplant listing-free survival, hemodynamics, exercise capacity, and subjective status was investigated. During the 24-month study period, 33 patients dropped out of the study; 153 patients finished the study protocol. Twenty-seven patients died or had a listing for heart transplantation: 16 in the placebo group and 11 in the diltiazem group. The transplant listing-free survival rate was 85% for diltiazem and 80% for placebo recipients (P = .444). After 24 months, only diltiazem significantly increased cardiac index at rest (P = .01) and under a workload (P = .02), systolic and diastolic pressures (P = .003 and P = .004), stroke volume index (P = .003), and stroke work index (P = .000) and decreased both pulmonary artery pressure under workload (P = .007) and heart rate (P = .001). Diltiazem also increased exercise capacity (P = .002) and subjective well-being (P = .01). Adverse reactions were minor and evenly distributed in both groups, except for an increase in the PQ interval in the diltiazem group.

CONCLUSIONS

In patients with IDC, the adjunct therapy of diltiazem improves cardiac function, exercise capacity, and subjective status without deleterious effects on transplant listing-free survival.

Treatment of end stage dilated cardiomyopathy

Patients should be referred for cardiac transplantation only after all other means of management of congestive heart failure have been attempted and have been unsuccessful (table 3). An adequate therapeutic trial of conventional and experimental agents including beta blockade and vesnarinone should be completed and be shown to be unsuccessful before transplantation is considered in patients in NYHA class III. Prospective clinical trials need to be completed to define the role of newer therapeutic options. The scarcity of donor organs will probably preclude the use of cardiac transplantation in all patients who may benefit. Alternative methods of cardiac replacement (such as dynamic cardiomyoplasty, permanent implantable mechanical circulatory assistance, and xenografting) must be developed. These methods coupled with better pharmacological treatment will greatly improve the outcome of patients with dilated cardiomyopathy.

Intravenous diltiazem for the treatment of patients with atrial fibrillation or flutter and moderate to severe congestive heart failure

The objective of this multicenter, randomized, double-blind, placebo-controlled study was to determine the safety and efficacy of intravenous diltiazem in the treatment of 37 patients with rapid (ventricular rate, mean +/- SD 142 +/- 17 beats/min) atrial fibrillation or flutter and moderate to severe congestive heart failure (ejection fraction, mean +/- SD 36 +/- 14%; New York Heart Association class III [23 patients], class IV [14 patients]). During the double-blind portion of the study, patients received either intravenous diltiazem, 0.25 mg/kg over 2 minutes, or placebo followed 15 minutes later by diltiazem or placebo, 0.35 mg/kg over 2 minutes, if the first dose was tolerated but ineffective. Placebo nonresponders were given open-label intravenous diltiazem in a similar fashion as in the double-blind portion of the study. In the double-blind part of the study, 21 (18 with 0.25 mg/kg, 3 with an additional 0.35 mg/kg) of the 22 patients (95%) responded to diltiazem, and 0 of 15 patients (0%) responded to placebo (p < 0.001). All 15 patients (13 with 0.25 mg/kg and 2 with an additional 0.35 mg/kg) who received placebo during the double-blind period had a therapeutic response to diltiazem during open-label therapy. Overall, 36 of 37 patients (97%) had a therapeutic response to intravenous diltiazem. Heart rate response to diltiazem after the 2-minute bolus infusions consisted of a > or = 20% decrease in heart rate from baseline in 36 patients; in addition, 17 patients also had heart rates decreased to < 100 beats/min, whereas no patient had conversion to sinus rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetic cardiomyopathy

Diabetic cardiomyopathy as a distinct entity was first recognized by Rubler et al. in diabetics with congestive heart failure (CHF), who had no evidence of coronary atherosclerosis. The Framingham study showed a 2.4-fold increased incidence of CHF in diabetic men and a 5.1-fold increase in diabetic women over 18 years. Pathological studies show left ventricular hypertrophy and fibrosis with varying degrees of small vessel disease, the functional significance of which is uncertain. Hypertension was recognized as an important cofactor in the development of fatal congestive heart failure in diabetics. On cardiac catheterization, in patients symptomatic of heart failure, either congestive or restrictive patterns have been observed. In contrast, asymptomatic diabetics had decreased left ventricular compliance but normal systolic function on hemodynamic study. Noninvasive studies show alterations in systolic and especially diastolic function, particularly in diabetics with microvascular complications and/or coexistent hypertension. Using load-independent measures of contractility, however, systolic function was generally found to be normal in asymptomatic normotensive diabetics. Experimental studies have focused on the mildly diabetic dog and the severely diabetic rat. Decreased left ventricular compliance and increased interstitial connective tissue were observed in chronically diabetic dogs. In contrast, ventricular myocardium from diabetic rats exhibits a reversible decrease in the speed of contraction, prolongation of contraction, and a delay in relaxation. These mechanical changes are associated with a decreased myosin ATPase, a shift in myosin isoenzyme distribution, alterations in a variety of Ca2+ fluxes, and changes in responses to alpha- and beta-adrenergic and cholinergic stimulation. These biochemical changes may be secondary to alterations in carbohydrate, lipid, and adenine nucleotide metabolism in the diabetic heart.(ABSTRACT TRUNCATED AT 250 WORDS)

Viral myocarditis: a paradigm for understanding the pathogenesis and treatment of dilated cardiomyopathy

Although an etiologic link between viral myocarditis and idiopathic dilated cardiomyopathy has long been recognized, the actual extent of this relation has been uncertain. In this review, we examine recent developments in the molecular analysis of endomyocardial biopsy specimens, particularly techniques for gene amplification, which have unequivocally confirmed this relation and given us some insight into its significance. In addition, we show that viral myocarditis in a murine model is associated with spasm of the coronary microvasculature, leading to myocyte necrosis, fibrosis, calcification and cardiac dilation. These findings are similar to those seen in the hearts of genetically cardiomyopathic hamsters, rats and humans with hypertension and diabetes, rats after acute brain injury and models of Chagas' disease. Treatment of microvascular spasm with verapamil, captopril or alpha 1-adrenergic blocking agents appears to interrupt this pathway and has been shown to markedly impede the evolution of dilated cardiomyopathy in the genetic hamster model and a murine model of myocarditis. There is some suggestion that digitalis, though beneficial during cardiac decompensation, may actually be detrimental when administered during the early stages of myocardial disease. These experiments have led to a new paradigm for the pathogenesis of cardiomyopathy after viral myocarditis, as well as a general hypothesis for the pathogenesis of some types of dilated cardiomyopathy. They also suggest that the selection of therapeutic agents for some forms of dilated cardiomyopathy may differ significantly between the early and late stages of the disease.

Calcium channel blockers in heart failure

The rationale for the use of calcium channel blockers in patients with chronic heart failure lies in their vasodilator action, antiischemic effect, ability to lessen left ventricular diastolic dysfunction and data showing their effect in preventing progression of myocardial dysfunction in animals with cardiomyopathy. Despite initial studies reporting improvement of the hemodynamic profile with nifedipine, further evaluation showed variable results, with hemodynamic worsening seen in up to 29% of patients. Longer-term controlled studies evaluating symptoms and clinical status demonstrated worsening chronic heart failure in approximately 25% of patients within 8 weeks of nifedipine therapy. Although diltiazem has a lesser myocardial depressant effect and its short-term use was associated with less frequent hemodynamic and clinical worsening, long-term exposure to the drug in a large group of patients with chronic heart failure due to left ventricular systolic dysfunction after myocardial infarction resulted in an increased incidence of cardiac events, with worsening heart failure and death. The use of verapamil in a similar patient cohort showed the loss of its demonstrated protective effect in patients with clinical evidence of heart failure. In an attempt to improve the safety of calcium channel blockers, the following approaches were suggested: 1) use of second-generation drugs with less myocardial depressant effect; 2) concomitant use of angiotensin-converting enzyme inhibitors to prevent reported neurohormonal activation; and 3) development of drugs with favorable neurohormonal effects. These approaches led to mixed results.(ABSTRACT TRUNCATED AT 250 WORDS)

Vasodilators. A re-evaluation of their role in heart failure

Over the past 25 years, the concept of circulation in heart failure has evolved from that of a simple circuit with a weak pump and high pressures to a complex integrated system of cellular modification, cardiac compensation and systemic neurohumoral responses. The original model of cardiac afterload as the systemic vascular resistance has been refined to reflect the interdependence of preload and afterload and the central role of atrioventricular valve regurgitation. It is becoming increasingly apparent that the impact of vasodilator therapy far exceeds the direct haemodynamic effects on preload and afterload, and depends on the mechanism by which vasodilation is achieved, with increasing emphasis on those agents which oppose neurohumoral activation. The potential goals of therapy have broadened to include not only haemodynamic stabilisation through tailored therapy for patients referred with advanced heart failure, but also the prevention of disease progression for patients with asymptomatic ventricular dilation. As the different profiles of heart failure have come to be recognised, the purpose and design of vasodilator treatment must now be considered individually for each patient.

Calcium antagonists and left ventricular function

Calcium antagonists impede the entry of calcium into myocytes and inhibit myocardial contraction. Calcium antagonists differ in their relative negative inotropic potency and can provoke baroreceptor stimulation that modulates left ventricular (LV) performance. Calcium antagonists are uniformly well tolerated in patients with normal LV function. Use of these agents in patients with suspected LV function impairment has yielded results ranging from hemodynamic improvement to clinical deterioration and increased mortality. Reports of clinical deterioration when calcium antagonists were combined with beta blockers underscore the importance of reflex adrenergic support for the myocardium. Although calcium antagonists are potent vasodilators and produce short-term hemodynamic improvement, they are not useful as primary treatment in patients with congestive heart failure (CHF). They may have a place in the treatment of coexistent problems in patients with LV dysfunction. Short-term use of calcium antagonists for myocardial ischemia or rapid atrial fibrillation is probably safe in the presence of LV dysfunction and overt CHF. Calcium antagonists appear to have a role in the treatment of patients with diastolic dysfunction of diverse etiologies.

Beneficial effects of diltiazem on the natural history of hypertensive diabetic cardiomyopathy in rats

Hypertensive diabetic rats develop a cardiomyopathy characterized by systolic and diastolic ventricular dysfunction, myocardial hypertrophy and fibrosis, pulmonary congestion and a very high mortality rate. Alterations in contractile proteins and sarcoplasmic reticular calcium (Ca2+) transport in diabetic myocardium and their partial reversal with verapamil suggest that calcium channel blockade may prevent death from congestive heart failure in hypertensive diabetic rats. A large group of rats with renovascular hypertension and streptozotocin diabetes were divided into four groups: untreated animals (Group 1) and animals treated with 100 (Group 2), 300 (Group 3) or 600 (Group 4) mg/kg per day of sustained release diltiazem mixed in their food. Treatment was begun shortly after the onset of hypertension and diabetes. Mortality rates after 4 months were 59% (19 of 32), 53% (17 of 32), 27% (7 of 26) and 35% (12 of 34) in Groups 1, 2, 3 and 4, respectively; the mortality rate in age-matched control rats was 5% (1 of 19). The reductions in mortality rates in Groups 3 and 4 were statistically significant. Diltiazem did not change systolic blood pressure, serum glucose concentration, heart rate or left ventricular mass. There was a trend to decreased left ventricular interstitial fibrosis and perivascular fibrosis in diltiazem-treated animals. Ventricular collagen concentration was similar in untreated hypertensive diabetic and control rats; levels were higher in hypertensive diabetic rats that died than in those that survived. There was a trend to decreased collagen concentration as diltiazem dose increased. Myosin isoenzyme distribution was not changed in Groups 3 and 4 (in comparison with Group 1). In all hypertensive diabetic groups, rats that died had a higher blood pressure, heart rate, relative left ventricular mass, lung weight and lung water than did survivors. The mortality rate was two to three times higher among rats with an initial blood pressure greater than or equal to 180 mm Hg. The beneficial effects of diltiazem on survival were most significant among rats with severe hypertension.