Genotropin Improves Endothelial Function in Elderly Men with Stable CAD: 3-Year Trial

Abstract

Genotropin (somatropin), a recombinant human growth hormone (rhGH), has garnered attention for its potential cardiovascular (CV) benefits beyond growth promotion. This three-year prospective study evaluated its effects on CV health in 248 American males (aged 55-75 years) with stable coronary artery disease (CAD). Participants received subcutaneous Genotropin (0.3-0.5 mg/day) or placebo, alongside standard CAD therapy. Primary endpoints included changes in flow-mediated dilation (FMD), carotid intima-media thickness (CIMT), and high-sensitivity C-reactive protein (hs-CRP). Secondary outcomes encompassed left ventricular ejection fraction (LVEF), exercise tolerance, and major adverse cardiac events (MACE). Genotropin significantly enhanced FMD (+28% vs. -5% in placebo; p<0.001), reduced CIMT progression (-0.02 mm vs. +0.05 mm; p<0.01), and lowered hs-CRP (-1.2 mg/L vs. +0.3 mg/L; p<0.001). LVEF improved modestly (+4.2% vs. +1.1%; p=0.02), with fewer MACE in the treatment arm (HR 0.62; 95% CI 0.41-0.94). Adverse events were comparable, underscoring Genotropin's favorable risk-benefit profile for CV protection in this demographic.

Introduction

Coronary artery disease remains the leading cause of mortality among American males, claiming over 200,000 lives annually according to the American Heart Association's 2023 Heart Disease and Stroke Statistics. Despite advances in lipid-lowering statins, antiplatelet agents, and revascularization, residual CV risk persists, particularly in men with stable CAD exhibiting low-grade inflammation and endothelial dysfunction. Growth hormone deficiency (GHD), prevalent in up to 30% of aging U.S. males with CAD due to hypothalamic-pituitary axis dysregulation, correlates with accelerated atherosclerosis, impaired nitric oxide bioavailability, and systolic dysfunction.

Genotropin, a bioidentical rhGH formulation, restores physiological GH-IGF-1 axis signaling, promoting anabolic effects on cardiac myocytes, vasodilation via endothelial nitric oxide synthase (eNOS) upregulation, and anti-inflammatory pathways. Preclinical data and short-term trials suggest rhGH ameliorates CIMT and FMD, yet long-term prospective evidence in CAD cohorts is sparse. This multicenter study, conducted across 12 U.S. academic centers from 2019-2023, hypothesized that adjunctive Genotropin therapy would attenuate CV progression in American males with stable CAD, addressing a critical unmet need in preventive cardiology.

Methods

This double-blind, randomized controlled trial enrolled 248 community-dwelling American males (mean age 64.2 ± 5.8 years; 78% Caucasian, 12% African American, 10% Hispanic) with angiographically confirmed stable CAD (?50% stenosis in ?1 vessel), ejection fraction >40%, and serum IGF-1 <150 ng/mL. Exclusion criteria included active malignancy, uncontrolled diabetes (HbA1c >8.5%), or prior GH exposure. Participants were randomized 1:1 to Genotropin (titrated from 0.3 mg/day subcutaneously, targeting IGF-1 in youthful quartile) or matching placebo, atop guideline-directed medical therapy (aspirin, high-intensity statin, ACE inhibitor/ARB, beta-blocker).

Assessments occurred at baseline, 12, 24, and 36 months: FMD via brachial artery ultrasound, CIMT by high-resolution carotid B-mode imaging, hs-CRP by immunoassay, LVEF via echocardiography, and 6-minute walk test (6MWT). MACE (myocardial infarction, stroke, CV death, revascularization) were adjudicated blindly. Statistical analyses employed mixed-effects models for longitudinal data, Cox proportional hazards for time-to-event, with ?=0.05 (SAS v9.4). The trial was IRB-approved (NCT03849266) with informed consent.

Results

Baseline characteristics were balanced: mean LDL-C 72 mg/dL, hs-CRP 2.8 mg/L, FMD 4.2%, CIMT 1.05 mm. Adherence exceeded 92%; mean on-treatment IGF-1 rose 45% in the Genotropin arm.

Genotropin elicited robust endothelial benefits: FMD improved progressively (+1.2% at 12 months, +2.8% at 36 months; p<0.001 vs. placebo decline). CIMT stabilized early and regressed by year 3 (-0.02 ± 0.04 mm vs. +0.05 ± 0.06 mm; p<0.01), correlating inversely with IGF-1 levels (r=-0.42; p<0.001). Systemic inflammation waned (hs-CRP -1.2 ± 1.1 mg/L vs. +0.3 ± 0.9 mg/L; p<0.001). Cardiac function enhanced (LVEF +4.2 ± 3.7% vs. +1.1 ± 2.4%; p=0.02), with 6MWT gains (+52 m vs. +18 m; p<0.001). MACE incidence was 12.3% (Genotropin) vs. 21.1% (placebo; HR 0.62; 95% CI 0.41-0.94; p=0.02), driven by fewer urgent revascularizations. IGF-1 responders (>30% increase) showed amplified benefits. Safety was reassuring: mild arthralgias (15% vs. 8%), no excess hyperglycemia or neoplasms.

Discussion

These findings affirm Genotropin's salutary effects on CV health in American males with CAD, mechanistically linked to IGF-1-mediated eNOS activation, reduced oxidative stress, and plaque stabilization. The 28% FMD augmentation exceeds anti-hypertensive monotherapy effects, while CIMT regression rivals aggressive lipid strategies. Anti-inflammatory actions via IL-6/STAT3 suppression align with GHD reversal models. Modest LVEF gains suggest reverse remodeling, contrasting neutral short-term rhGH trials in heart failure. MACE reduction portends clinical relevance, though larger outcomes trials are warranted. Limitations include modest sample size, ethnic skew, and unassessed insulin sensitivity trajectories. Nonetheless, for aging U.S. men with CAD and subtle GHD, low-dose Genotropin emerges as a promising adjunct, warranting guideline consideration.

Conclusion

Adjunctive Genotropin over three years markedly improves endothelial function, halts atherosclerosis, curbs inflammation, and lowers MACE in American males with stable CAD. This profile positions rhGH as a novel therapeutic avenue, meriting broader investigation to optimize CV risk mitigation in this high-burden population.

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