Pathologic hypertrophy with fibrosis: the structural basis for myocardial failure.

Area of Science:

• Cardiovascular Medicine
• Pathology
• Pharmacology

Background:

• Left ventricular hypertrophy (LVH) is a major risk factor for cardiovascular events.
• LVH-related adverse outcomes stem from structural disruption, specifically myocardial fibrosis, rather than increased heart muscle mass alone.
• This fibrosis impairs the electrical and mechanical functions of the hypertrophied heart.

Purpose of the Study:

• To investigate the mechanisms behind fibrillar collagen accumulation in the heart.
• To determine the role of the renin-angiotensin-aldosterone system in myocardial fibrosis.
• To explore the potential for reversing cardiac fibrosis and improving heart function.

Main Methods:

• In vivo studies in animals examining myocardial fibrosis in relation to mineralocorticoid excess and hemodynamic workload.
• In vitro studies using cultured cardiac fibroblasts to assess the effects of hormones on collagen synthesis.
• Pharmacological interventions including aldosterone receptor antagonists and angiotensin-converting enzyme (ACE) inhibitors.

Main Results:

• Myocardial fibrosis is linked to chronic mineralocorticoid excess, independent of workload, and can occur in various forms of hypertrophy.
• Aldosterone receptor antagonists and ACE inhibitors effectively prevented or reversed myocardial fibrosis in animal models.
• In vitro, aldosterone and angiotensin II were found to stimulate fibroblast collagen synthesis.

Conclusions:

• Myocardial fibrosis, driven by hormones of the renin-angiotensin-aldosterone system, is a key structural basis for pathological hypertrophy and cardiovascular events.
• Pharmacological interventions targeting this system show promise for cardioreparation and treating heart failure.
• Reversing cardiac fibrosis may offer a new therapeutic strategy for heart failure management.