ABSTRACT
BACKGROUND: The impact of angiotensin-converting enzyme (ACE) gene polymorphism on neurohormonal dose response to ACE inhibitor therapy is unclear. METHODS: ACE Insertion (I) or Deletion (D) genotype was determined in 74 patients with chronic heart failure who were randomly assigned to receive either high-dose or low-dose enalapril over a period of 6 months. Monthly pre-enalapril and post-enalapril neurohormone levels (serum ACE activity (sACE), plasma angiotensin II (A-II), plasma renin activity (PRA), and serum aldosterone (ALDO) were compared between genotype subgroups and between patients who received high- or low-dose enalapril within each genotype subgroup. RESULTS: At baseline, predose/postdose sACE and postdose PRA were significantly higher in the DD genotype. At 6-month follow-up, postdose sACE was reduced in a dose-dependent fashion in all three genotypes (P < .05). However, predose and postdose ALDO and A-II levels did not differ between each genotype subgroup at baseline or by enalapril dose within each genotype subgroup. ALDO escape and A-II reactivation were not affected by ACE genotype or enalapril dosage. CONCLUSIONS: Predose sACE were consistently higher in the DD genotype when compared with ID or II subgroups. Despite a dose-dependent suppression of sACE, there were no observed statistically significant differences in ALDO and A-II suppression or escape with escalating doses of enalapril within each subgroup.
Subject(s)
Angiotensin-Converting Enzyme Inhibitors/administration & dosage , Enalapril/administration & dosage , Heart Failure/genetics , Neurotransmitter Agents/blood , Peptidyl-Dipeptidase A/genetics , Polymorphism, Genetic , Aldosterone/blood , Angiotensin II/blood , Dose-Response Relationship, Drug , Double-Blind Method , Female , Genotype , Heart Failure/blood , Heart Failure/drug therapy , Humans , Male , Middle Aged , Peptidyl-Dipeptidase A/blood , Renin/bloodABSTRACT
OBJECTIVES: We sought to compare the neurohormonal responses and clinical effects of long-term, high-dose versus low-dose enalapril in patients with chronic heart failure (CHF). BACKGROUND: Examination of neurohormonal and clinical responses in patients receiving different doses of angiotensin-converting enzyme (ACE) inhibitors may provide insight into the potential for additional suppression with angiotensin II (AT-II) or aldosterone antagonists. METHODS: Seventy-five patients with CHF were randomized to receive either high-dose (40 mg/day, n = 37) or low-dose (5 mg/day, n = 38) enalapril over six months. The results from exercise testing, echocardiography, tissue-specific ACE activity and monthly pre- and post-enalapril neurohormonal levels were compared. RESULTS: Despite greater intra-group improvements in plasma renin activity and serum aldosterone levels in the high-dose group, no statistically significant differences were observed between the two groups in all variables, except for serum ACE activity at the end of study. Elevated serum aldosterone and plasma AT-II levels were observed in 35% and 85% of patients, respectively, at 34 weeks, an inter-group difference that was not statistically significant. A trend toward higher levels of tissue-specific ACE activity in the high-dose group compared with the low-dose group at the end of study was observed (p = 0.054). A predefined composite end point of clinical events had a trend toward better improvement in the high-dose group. CONCLUSIONS: This study could not demonstrate a difference between high- and low-dose enalapril in terms of serum aldosterone and plasma AT-II suppression, despite a dose-dependent reduction in serum ACE activity. Even at maximal doses of enalapril, elevated serum aldosterone and plasma AT-II levels were frequently observed.
