High-Dose Aldactone for Treatment of Diuretic Resistant Heart Failure

Congestive heart failure (CHF) is common and currently affects an estimated 6.6 million adults in the United States (1). In addition being highly prevalent, CHF is responsible for ~ 1 million hospital discharges per year and approximately 50% of patients with CHF will die within 5 years making it a highly morbid and lethal disease (1).

Manifestations of CHF include symptoms of volume overload such as dyspnea, abdominal bloating and/or fatigue. The genesis of these symptoms begins with loss of the integrity of arterial circulation due to decreased cardiac output (2). Decreased activation of mechanoreceptors in the carotid sinus, left ventricle, aortic arch and renal afferent arterioles due to lower systemic arterial pressure stimulates the sympathetic nervous system (SNS), renal-angiotensin-aldosterone system (RAAS) and non-osmotic release of arginine vasopressin (3). As a result, sodium reabsorption in the proximal tubule followed by water absorption increases causing accumulation of intravascular volume to compensating for arterial underfilling (4). Consequently, activation of neurohumoral reflexes result in increased cardiac afterload and preload, cardiac remodeling, hyponatremia and pulmonary edema (5). Renal vasoconstriction, sodium and water retention leads to a continuous positive feedback loop of further salt and water accumulation accompanied by further renal vasoconstriction (6).

Diuretic therapy is the most common means to relieve congestion in acute decompensated heart failure (ADHF) and approximately 90% of patients are treated with loop diuretics (7). Although loop diuretics are a cornerstone ADHF care and carries the highest level of recommendation by the American Heart Association (Class I); the guideline is supported by the lowest level of evidence (Class C) (8). While effective at natriuresis, loop diuretics are known to stimulate the SNS and RAAS, both of which have adverse consequence in heart failure (9,10). Not only is the RAAS system stimulated due to changes in arterial filling, furosemide blocks sodium chloride transport at the macula densa causing renin release independent of renal sodium loss (11). With increase stimulation of renin release, vasoconstriction of the renal artery ensues causing or further exacerbating renal insufficiency (12). Long-term utilization of loop diuretics results in hypertrophy of the distal nephron and increased expression of a sodium chloride co-transporter (13). These changes along with increased aldosterone levels further enhances distal sodium reabsorption and prevents aldosterone escape (14).

In treating heart failure patients as a population, diuretic resistance is encountered commonly and escalating doses of furosemide may be utilized to achieve fluid loss (15). Clinically, use of high-doses of loop diuretics is associated with greater rates of clinical events such as mechanical ventilation and myocardial infarction compared to low-dose loop diuretics (16). High-dose loop diuretic administration is associated with worsening renal function (17), increased length of hospital stay and greater in-hospital mortality (17-19). There is in fact a linear correlation with diuretic dose and mortality (20).

Given the potential hazards of administering loop diuretics in CHF patients, the remaining options are limited. Changing diuretics strategies from bolus to continuous loop diuretic infusion does not appear to change overall outcomes (21). Alternative strategies for relieving congestion include inhibition of the distal nephron using thiazide diuretics. Thiazide diuretics work synergistically with loop diuretics to induce natriuresis but have an independent association with worsening renal function and death (20,22). Utilizing inotropes to increasing renal perfusion pressure may improve natriuresis, however, it comes with the price of increasing mortality regardless of whether beta-adrenergic agonists (dobutamine) or phosphodiesterase inhibitors are used (23,24). Ultrafiltration and mechanical unloading of the heart is another therapeutic option, however it was found to be ineffective and associated with worsening renal function (25). Even low doses of dopamine or nesiritide were not effective in improving outcomes in patients with cardiorenal syndrome (26). Higher doses of spironolactone were recently shown to be safe in a prospective cohort treated for acute decompensated heart failure (27). Recently a case report was published showing that patients hospitalized with congestive heart failure, worsening renal function and diuretic resistance were able to be diuresed without adverse effect on renal function or hyperkalemia by treating with escalating doses of spironolactone (28)