Variability of Myocardial Strain During Isometric Exercise in Subjects With and Without Heart Failure

Area of Science:

• Cardiology
• Medical Imaging
• Biomedical Engineering

Background:

• Fast strain-encoded cardiac magnetic resonance imaging (cMRI, fast-SENC) is a novel technique for quantifying cardiac strain, potentially enhancing heart failure (HF) characterization.
• Investigating the impact of isometric handgrip exercise (HG) on cardiac strain using fast-SENC in HF patients and healthy controls is crucial for understanding cardiac response.
• This study aims to describe the changes in left ventricular (LV) global longitudinal strain (GLS) and global circumferential strain (GCS) during HG exercise in various HF subgroups and controls.

Observation:

• The study included 72 participants: 18 HFrEF, 18 HFmrEF, 17 HFpEF, and 19 controls.
• LV GLS response to HG exercise was heterogeneous across all groups, with no significant difference in mean GLS change between HF subgroups and controls.
• However, the absolute magnitude of LV GLS change during HG exercise was significantly greater in HF patients compared to controls.

Findings:

• The absolute value of LV GLS change during HG exercise was significantly elevated in HF patients (HFpEF, HFmrEF, HFrEF) compared to controls (p=0.005).
• This absolute LV GLS change demonstrated a significant correlation with resting left ventricular ejection fraction (LVEF), NTproBNP levels, and Minnesota Living with Heart Failure questionnaire scores.
• The findings suggest that while the pattern of GLS response is variable, the extent of strain change during isometric stress is a marker of HF severity.

Implications:

• The absolute change in LV GLS during isometric handgrip exercise, assessed by fast-SENC, may serve as a valuable indicator of heart failure severity.
• Despite heterogeneous strain responses, the magnitude of GLS change during HG exercise is associated with established markers of HF, suggesting potential clinical utility.
• The diagnostic utility of fast-SENC strain assessment combined with HG exercise appears limited for differentiating HF subtypes based on strain response patterns alone, but the magnitude of change holds significance.