Complex electrophysiological remodeling in postinfarction ischemic heart failure.

Area of Science:

• Cardiovascular Physiology
• Cardiac Electrophysiology
• Translational Research

Background:

• Heart failure (HF) post-myocardial infarction (MI) significantly increases cardiac arrhythmia risk.
• Electrophysiological remodeling in ischemic HF is not fully understood, particularly in large animal models.

Purpose of the Study:

• To systematically measure major ionic currents in ventricular myocytes from infarct border and remote zones in a porcine model of post-MI HF.
• To elucidate the electrophysiological remodeling contributing to arrhythmias in HF.

Main Methods:

• Utilized self-AP-clamp sequential dissection to record eight ionic currents under physiological conditions.
• Compared ionic currents in healthy controls versus HF-remote and HF-border zone myocytes.

Main Results:

• HF myocytes showed altered ionic currents, including increased late Na+, Ca2+-activated K+, and Ca2+-activated Cl- currents, and decreased rapid delayed rectifier K+ current.
• Border zone myocytes also had decreased L-type Ca2+ and inward rectifier K+ currents, with delayed after-depolarizations.
• Differential remodeling resulted in shortened AP in border zones and prolonged AP in remote zones, increasing repolarization inhomogeneity.

Conclusions:

• The integrated impact of multiple ionic current changes, not just individual ones, drives arrhythmogenesis in post-MI HF.
• Understanding this complex interplay is crucial for developing effective anti-arrhythmia strategies, as single-channel blockers may be insufficient.