Left ventricular torsion, energetics, and diastolic function in normal human aging

Area of Science:

• Cardiology
• Physiology
• Biophysics

Background:

• Normal aging affects cardiac function, but the underlying mechanisms, particularly energetic deficits, remain unclear.
• Understanding age-related changes in cardiac function is crucial for distinguishing normal aging from cardiovascular disease.

Purpose of the Study:

• To investigate the relationship between normal aging, left ventricular function, and myocardial energetics.
• To determine if impaired cardiac function in aging is linked to underlying energetic defects.

Main Methods:

• Cardiac magnetic resonance imaging with tissue tagging was used to assess left ventricular structure and function.
• Phosphorus-31 magnetic resonance spectroscopy ((31)P MRS) measured myocardial energetics, specifically the phosphocreatine-to-ATP ratio (PCr/ATP).
• 49 healthy subjects aged 20-69 years were studied to evaluate age-related changes.

Main Results:

• Increasing age was associated with decreased early filling percentage (EFP), indicating impaired diastolic filling (r = -0.72, P < 0.0001).
• Age correlated with an increased torsion-to-shortening ratio (TSR), suggesting relative subendocardial dysfunction (r = 0.44, P < 0.02).
• The PCr/ATP ratio decreased with age (r = -0.52, P < 0.003), but EFP and TSR were not significantly related to PCr/ATP.

Conclusions:

• Normal aging leads to impaired early diastolic filling and relative subendocardial dysfunction.
• While energetics (PCr/ATP) decline with age, they do not appear to be the primary drivers of observed functional changes in systolic and diastolic function.
• The observed functional changes in aging likely share a common pathophysiology unrelated to energetics.