Does normal pump function belie muscle dysfunction in patients with chronic severe mitral regurgitation?

Area of Science:

• Cardiology
• Cardiovascular Physiology

Background:

• Chronic severe mitral regurgitation (MR) can affect left ventricular function.
• Assessing myocardial contractile function in MR is crucial for surgical decision-making.

Purpose of the Study:

• To evaluate left ventricular contractile function in patients with chronic severe MR.
• To correlate ejection fraction (EF) and afterload with myocardial function.
• To assess the impact of MR on myocardial stiffness.

Main Methods:

• Simultaneous left ventricular cineangiography and micromanometry in 27 MR patients and 23 normal subjects.
• Pharmacologic load manipulation to assess stress-strain relationships.
• Calculation of ejection fraction (EFc) and end-systolic stress (sigma es).

Main Results:

• A normal inverse relationship between EFc and sigma es was observed in the normal group.
• In the MR group, 10/14 with EF < 0.60 showed muscle dysfunction.
• Maximum myocardial stiffness (maxEN) was not significantly different between MR and normal groups.
• Ejection fraction (EF) was similar between MR (0.62 ± 0.13) and normal (0.65 ± 0.08) groups.

Conclusions:

• Contractile function is frequently normal in MR patients with normal EF.
• Depressed EF in MR patients may indicate muscle dysfunction, but does not preclude successful mitral valve surgery.
• Mitral valve surgery improved symptoms in most patients, despite underlying contractile dysfunction.