Mineralocorticoid Receptor Antagonists in the Management of Heart Failure and Resistant Hypertension: A Review.

IMPORTANCE: Heart failure (HF), with or without reduced ejection fraction, and multidrug-resistant hypertension (RHT) are major worldwide health problems of ever-increasing proportions. The mineralocorticoid receptor antagonists (MRAs) spironolactone and eplerenone have proved valuable additions to the overall management of these disorders in patients without significant renal dysfunction. OBSERVATIONS: Neurohormonal activation, including aldosteronism, in HF and RHT, has provided the pathophysiologic basis for the inclusion of MRA in the overall management of these disorders and the respective survival benefit and control of blood pressure. Furthermore, MRAs attenuate the appearance of secondary hyperparathyroidism that accompanies excretory Ca2+ losses induced by aldosteronism in which elevated parathyroid hormone levels raise the risk of adverse cardiovascular events and atraumatic bone fracture. Serial surveillance of serum electrolytes and creatinine levels is mandated to avoid serious hyperkalemia (potassium concentration >5.5 mEq/L) and its attendant risks in patients receiving MRAs. CONCLUSIONS AND RELEVANCE: Mineralocorticoid receptor antagonists are a valuable addition to the practice of medicine. Their judicious use in patients with HF or RHT can improve treatment of these patients.

Atrophied cardiomyocytes and their potential for rescue and recovery of ventricular function.

Cardiomyocytes must be responsive to demands placed on the heart's contractile work as a muscular pump. In turn, myocyte size is largely dependent on the workload they perform. Both hypertrophied and atrophic myocytes are found in the normal and diseased ventricle. Individual myocytes become atrophic when encumbered by fibrillar collagen, such as occurs at sites of fibrosis. The mechanisms include: (a) being immobilized and subject to disuse with ensuing protein degradation mediated by redox-sensitive, proteolytic ligases of the ubiquitin-proteasome system and (b) dedifferentiated re-expressing fetal genes induced by low intracellular triiodothyronine (T3) via thyroid hormone receptor ß1. This myocyte-selective, low T3 state is a consequence of heterocellular signaling emanating from juxtaposed scar tissue myofibroblasts and their secretome with its de novo generation of angiotensin II. In a paracrine manner, angiotensin II promotes myocyte Ca(2+) entry and subsequent Ca(2+) overload with ensuing oxidative stress that overwhelms antioxidant defenses to activate deiodinase-3 and its enzymatic degradation of T3. In the failing heart, atrophic myocytes represent an endogenous population of viable myocytes which could be rescued to augment contractile mass, reduce systolic wall stress (afterload) and recover ventricular function. Experimental studies have shown the potential for the rescue and recovery of atrophic myocytes in rebuilding the myocardium--a method complementary to today's quest in regenerating myocardium using progenitor cells.