Left atrioventricular ratio (LA:LV): using left ventricular size as the reference for identifying maladaptive left...

Area of Science:

• Cardiology
• Cardiac Physiology
• Echocardiography

Background:

• Cardiac remodelling of the left atrium (LA) and left ventricle (LV) is a response to various stimuli.
• The inter-dependence of LA and LV remodelling is often overlooked.
• The left atrioventricular ratio (LA:LV) may help differentiate physiological from pathological cardiac remodelling.

Purpose of the Study:

• To evaluate the utility of the LA:LV ratio in distinguishing adaptive from maladaptive cardiac remodelling.
• To assess the relationship between LA:LV ratio, cardiorespiratory fitness (VO2peak), and cardiac structural differences.

Main Methods:

• A multi-centre international cohort study involving 2,943 adults (1,600 healthy, 1,343 with pathology).
• Echocardiography was used to assess the LA:LV ratio (maximal LA end-systolic volume to LV end-diastolic volume).
• Cardiorespiratory fitness was assessed as peak oxygen uptake (VO2peak) and categorized into quartiles.

Main Results:

• Healthy individuals had a median LA:LV of 0.49, while those with pathology showed higher ratios (0.53, p<0.001), particularly in atrial fibrillation (0.60) and heart failure with preserved ejection fraction (0.70).
• The highest indexed LA volumes were observed in the highest VO2peak quartile, but the LA:LV ratio was highest in the lowest VO2peak quartile.
• Among individuals with enlarged LA volumes, the concordance with an elevated LA:LV ratio varied significantly by fitness level, being higher in lower fitness quartiles.

Conclusions:

• The LA:LV ratio is an effective discriminator of adaptive versus maladaptive atrial remodelling.
• A typical LA:LV ratio is approximately 0.5; lower ratios correlate with higher functional capacity and physiological remodelling.
• LA:LV ratios of 0.75 or higher may indicate pathological remodelling and warrant further investigation for atrial pathology, especially when considered in the context of cardiorespiratory fitness.