Effect of nisoldipine on exercise performance in heart failure following myocardial infarction

Defining the role of calcium channel antagonists in heart failure due to systolic dysfunction

Calcium channel antagonists (CCAs) may either be divided into the dihydropyridines (e.g. amlodipine, felodipine, isradipine, lacidipine, nilvadipine, nifedipine, nicardipine etc.), the phenylalkylamines (e.g. verapamil) and the benzothiazepines (e.g. diltiazem) according to their chemical structure, or into first generation agents (nifedipine, verapamil and diltiazem) and second generation agents (subsequently developed dihydropyridine-derivatives). Second generation CCAs are characterized by greater selectivity for calcium channels in vascular smooth muscle cells than the myocardium, a longer duration of action and a small trough-to-peak variation in plasma concentrations. Heart failure is characterized by decreased cardiac output resulting in inadequate oxygen delivery to peripheral tissues. Although the accompanying neurohormonal activation, leading to vasoconstriction and increased blood pressure, is initially beneficial in increasing tissue perfusion, prolonged activation is detrimental because it increases afterload and further reduces cardiac output. At the level of the myocyte, heart failure is associated with increased intracellular calcium levels which are thought to impair diastolic function. These changes indicate that the CCAs would be beneficial in patients with heart failure. There has been a strong interest and increasing experience in the use of CCAs in patients with heart failure. Despite potential beneficial effects in initial small trials, findings from larger trials suggest that CCA may have detrimental effects upon survival and cardiovascular events. However, this may not necessarily be a 'class b' effect of the CCAs as there is considerable heterogeneity in the chemical structure of individual agents. Clinical experience with different CCAs in patients with heart failure includes trials that evaluated their effects on hemodynamic parameters, exercise tolerance and on symptomatology. However, the most relevant results are those from randomized clinical trials that assessed mortality as the primary endpoint. First generation CCAs have direct negative inotropic effects and even sustained release formulations have not proved any beneficial effect upon survival. With second generation CCAs, some benefit on hemodynamic parameters has been observed but none on survival, alone or in combination with ACE inhibitors. It is noteworthy that although amlodipine had a neutral effect on morbidity and mortality in large, randomized, placebo-controlled trials in patients with heart failure, the drug was well tolerated. There is no specific indication for CCAs (first or second generation) in patients with systolic heart failure, alone or in combination with ACE inhibitors, but amlodipine may be a considered in the management of hypertension or coronary artery disease in patients with heart failure.

[Evidence based medical treatment of heart failure]

INTRODUCTION AND OBJECTIVES

Recommendations for the treatment of heart failure were carried out by a systematic review of the available evidence of the different pharmacologic treatments.

MATERIAL AND METHODS

The review focused on the treatment of chronic and systolic heart failure. All the studies published in english about the pharmacologic treatment of heart failure where identified. The evidence of every pharmacologic treatment was classified according to: a) efficacy variables (reduction of mortality and hospitalizations, improvement of functional class, ejection fraction and exercise tolerance), and b) the level of quality of the evidence according to an evaluation scale. The evidence was also reviewed for the comparisons and the combinations of the pharmacologic treatments, as well as for the toxicity and costs of treatments.

RESULTS

The recommendations were defined according to the NYHA functional class and were classified in the A, B and C categories according to the level of quality of the available evidence. The evidence on mortality was considered the most important. First line drugs, the alternatives and other possible treatments were take into account.

CONCLUSIONS

There is enough evidence based on information about some variables such as reduction of mortality or hospitalizations to carry out treatment recommendations in all stages of heart failure. This point out the interest ant the priority of used them in the evaluation and improvement of the results of heart failure.

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.

Calcium antagonist use in congestive heart failure: still a bridge too far?

Calcium antagonists continue to be used to treat congestive heart failure (CHF), despite clinical evidence that they may exacerbate the disease. The systemic vasodilatory actions of these drugs make them potentially attractive for use as afterload reducing agents in patients with CHF. Newer calcium antagonists of the 1,4-dihydropyridine class, with claims of little or no negative inotropic properties and minimal effects on the sympathetic nervous system, seem a promising treatment of this disease. All calcium antagonists, however, consistent with their ability to block transmembrane calcium transport in cardiac muscle cells, are intrinsically negative inotropes. Moreover, clinical trial data are inconclusive about the ability of these newer calcium antagonists to activate the sympathetic nervous system. The relatively small numbers of patients with CHF, the differing degrees of CHF in different patient groups, and the variation in route of administration, dosage, and schedule of hemodynamic measurements make analyses of published data difficult. Although some patients with CHF respond positively to treatment with calcium antagonists, there is great individual variability of response, and the majority of patients show deterioration of myocardial function when taking calcium antagonists. Until conclusive clinical evidence of the safety and effectiveness of calcium antagonists in the treatment CHF is available, they should not be used to treat this disease unless individual patient characteristics clearly indicate a positive benefit/risk ratio.