Hemodynamic trial of sequential treatment with diuretic, vasodilator, and positive inotropic drugs in left ventricular failure following acute myocardial infarction

Nitrates for the Management of Acute Heart Failure Syndromes, A Systematic Review

Intravenous nitrates are widely used in the management of acute heart failure syndrome (AHFS) yet with lack of robust evidence to support their use. We therefore sought to analyze all randomized studies that evaluated the effects of nitrates on clinical outcomes in patients with AHFS. In total, 15 relevant trials comparing nitrates and alternative interventions in 1824 patients were identified. All but 3 were conducted before 1998. No trials demonstrated a beneficial effect on mortality, apart from 1 trial reporting a reduction in mortality, which was related to the time of treatment. Retrospective review suggests that there is a lack of data to draw any firm conclusions concerning the use of nitrates in patients with AHFS. More studies are needed to evaluate the safety and efficacy of these agents in the modern era of guideline-directed use of heart failure therapy.

Comparative efficacy of short-term intravenous infusions of milrinone and dobutamine in acute congestive heart failure following acute myocardial infarction. Milrinone-Dobutamine Study Group

The purpose of this study was to compare the hemodynamic and clinical effects of milrinone, a vasodilating and positive inotropic agent, with those of dobutamine in patients with congestive heart failure (CHF) following acute myocardial infarction (AMI). Thirty-three patients in Killip classification II or III within 12 h to 5 days after AMI were randomized in a multicenter, open-label clinical trial to receive a 24-h infusion of milrinone or dobutamine. Drugs were titrated to achieve at least a 30% increase in cardiac index (CI) from mean baseline or at least a 25% decrease in mean pulmonary capillary wedge pressure (MPCWP) from baseline. Both drugs improved CI, MPCWP, and other hemodynamic parameters. Criteria for decrease in MPCWP were met by 94% (15/16) of the milrinone-treated patients and 57% (8/14) of dobutamine-treated patients (p = 0.03). Both groups met the minimum efficacy criterion for CI. Maximal reduction in MPCWP over 0-3 h was greater in the milrinone group (-53.2%) than in the dobutamine group (-31.0%; p < or = 0.01); reductions were sustained over 24 h. Both drugs improved echocardiographic global ejection fraction and were generally well tolerated. The short-term infusion of milrinone may have a role in the management of CHF following AMI, especially when the aim is the rapid reduction of pulmonary congestion.

Diuretics in postinfarction heart failure

Severe left ventricular failure, as evidenced by radiographic pulmonary edema or raised left ventricular filling pressure, accompanying acute myocardial infarction, carries a high mortality risk. In this situation, the intravenous loop-diuretic furosemide induces a rapid reduction in the raised left ventricular filling pressure due to an immediate and substantial increase in systemic venous compliance accompanied by increasing diuresis. This diuretic-induced venodilatation is probably due to the release of prostaglandins. The transient systemic arterial constriction and small increase in systemic blood pressure that follows intravenous furosemide probably results from the release of renin and subsequent activation of angiotensin. These diuretic induced hemodynamic changes are accompanied by restoration of the vasodilator reflex, which enables the heart to accommodate an acute volume load. Orally administered loop diuretics achieve slower, but similar, directional hemodynamic changes. There is no information on hemodynamic or neuroendocrine dose-response effects of loop diuretics, and there is no information pertaining to the use of other diuretic groups in this situation. The hemodynamic changes induced by furosemide summate with the changes induced by other anti-heart-failure drugs. In this subset of patients with acute myocardial infarction and severe heart failure, the influence of the diuretics on morbidity incidence and mortality risk remains to be measured.

Combination of positive inotropic and vasodilating substances in congestive heart failure

Therapy combining vasodilators and inotropic agents is considered to be one of the most powerful means of improving cardiac function in patients with congestive heart failure (CHF). The vasodilators enhance the effectiveness of inotropic agents by providing a reduction in preload and/or afterload. Inotropic drugs with different mechanisms of action, such as digitalis glycosides, ephedrine, dopamine, dobutamine, ibopamine, terbutaline, salbutamol, pirbuterol, prenalterol, amrinone, and milrinone, have been tested in combination with vasodilators with a predominant effect on preload (nitrates, molsidomine), with a predominant effect on afterload (hydralazine, nifedipine), or with a balanced action on both arterial and venous beds (nitroprusside, prazosin, captopril), showing positive results. The problem of the combination of digitalis glycosides and vasodilators with different sites of action has been considered by our group. In 42 patients with CHF, digoxin (DIG, 0.01 mg/kg intravenously) was tested in combination with molsidomine (MLS, 4 mg sublingually) (12 patients), a nitrate-like agent with a predominant vasodilating action on the capacitance vessels, nifedipine (NFP, 10 mg sublingually) (22 patients), a Ca2+ antagonist drug with a predominant action on the resistance vessels, and captopril (CPT, 25 mg orally) (8 patients), an ACE inhibitor with a balanced effect on both preload and afterload. The combination DIG plus MLS caused a reduction in left ventricular filling pressure (LVFP) greater than that achieved with either agent alone. The hemodynamic improvement was obtained without side effects, in spite of the striking fall in preload. We stress that this investigation was performed on patients with CHF following acute myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

A decade of developments in diuretic drug therapy

New diuretics introduced into clinical medicine during the past decade include potent new loop diuretics such as bumetanide and piretanide, the uricosuric indanyloxyacetic acid derivative indacrinone, and a new generation of sulfamoyl diuretics such as indapamide and xipamide, which are recommended primarily for the treatment of hypertension. Pharmacokinetic studies of individual diuretics have demonstrated that the diuretic and natriuretic responses to the newer agents generally follow the plasma drug concentration-time curves and urinary drug excretion rates. Therapeutic monitoring can therefore be achieved in most patients with edema or hypertension by close clinical observation and laboratory analysis of plasma electrolyte and creatinine concentrations and urinary electrolyte excretion rates. Interest in the mechanisms involved in the renal and extrarenal vascular actions of the newer diuretics has led to a better understanding of how changes in venous compliance, peripheral vascular resistance, and renal blood flow distribution may contribute to the overall therapeutic response to these agents, especially in patients with severe congestive heart failure, renal insufficiency with low glomerular filtration rates, and hypertension with cardiorenal complications. Adverse reactions to modern diuretics, which are mainly an extension of their renal pharmacodynamic effects, have proved to be minimal, provided that the dosage is adjusted to meet but not exceed individual patient requirements. However, the long-term consequences of prolonged periods of diuretic-induced alterations in plasma potassium levels, and metabolic effects that include elevated blood lipids, are still under investigation.

Congestive heart failure

A review of the epidemiology, pathophysiology, and treatment of congestive heart failure is presented, with particular attention given to newer modalities of therapy.