NEUROHORMONES IN PATIENTS WITH ISCHEMIC LEFT-VENTRICULAR DYSFUNCTION

Measurements of plasma neurohormones in patients with left ventricular dysfunction are generally performed for research purpose rather than for diagnostic purpose or to guide therapy. These studies have shown that in patients with left ventricular dysfunction, several neurohormonal systems were activated, even in the absence of symptoms of congestive heart failure. This suggested that the cardiovascular system was not in a steady state and pointed out potential culprits for the progression of the disease. It has also been shown that the levels of several of these markers, particularly plasma norepinephrine, had an important prognostic value. Another value of neurohormonal studies obviously is the design of new therapeutic approaches aimed at improving symptoms and prognosis. In this respect, important therapeutic successes have been obtained with agents that interfere with the actions of some of these neurohormonal systems, such as with the use of the angiotensin-converting enzyme (ACE) inhibitors, particularly captopril and enalapril, and to a lesser extent, with beta-blockers. It can therefore be expected that, in the future, most patients with severe ischemic dysfunction will be treated with an ACE inhibitor. Nonetheless, neurohormonal control is not complete with these drugs; powerful vasoconstrictor forces, such as endothelin-1, remain activated, and an escape of angiotensin II from the control of ACE inhibition may exist. Thus, morbidity (e.g., progression towards congestive heart failure and angina pectoris) and mortality remain high despite treatment with ACE inhibitors. In the search for further improvements, the new generation of long-acting dihydropyridines is worth considering. Their afterload reducing action, coupled with powerful coronary vasodilation, might hypothetically delay the progression of ischemic LV dysfunction. In addition, the improved pharmacokinetic profile of these drugs avoiding wide peak and trough variations in plasma levels may avoid triggering some neurohormonal reflexes.