Clinical Heart Failure
A growing body of literature supports the pivotal role of LA functional
failure leading to pulmonary congestion and symptom onset. Specifically,
atrial contractile failure to compensate for reservoir and/or conduit
dysfunction may lead to overt clinical heart failure32 (Figures 3). Atrial fibrillation leading
to failure of contractile compensation, may be large determinant of
symptom onset, and compensatory enhanced conduit function becomes
essential in this situation. Early exercise-induced symptoms may also be
related to conduit function failure in the setting of impaired reservoir
function 33. Advanced symptomatic HFpEF is
characterized by an eventual impairment in all three atrial functional
phases34 (Figures 2 and 3).
Hewing et al demonstrated that in patients with sinus rhythm, LA
reservoir, conduit, and contractile function all inversely correlated
with pulmonary capillary wedge pressure. However, LA contractile strain
could independently predict invasively measured pulmonary capillary
wedge pressure with a higher diagnostic accuracy than average E/E’
ratio35. Furthermore, Lundberg et al found LA strain
to outperform the current guideline recommended algorithm incorporating
E/e’, LA volume index, and max tricuspid regurgitation velocity in
determining invasively measured elevated pulmonary capillary wedge
pressure36.
Impaired LA reservoir strain may provide enhanced diagnostic accuracy
beyond conventional echocardiographic measures to discriminate true
HFpEF from non-cardiac dyspnea 37. Impaired resting LA
reservoir strain is associated with decreased peak oxygen
consumption38. LA reservoir strain normally increases
during exercise, but this typical exercise related augmentation is
blunted in symptomatic patients. Impaired LA reservoir augmentation with
exercise leads to right ventricular-pulmonary circulation uncoupling and
exercise ventilatory inefficiency39. Furthermore,
resting LA reservoir strain may outperformed LV GLS in its diagnostic
utility and prognostic ability for prediction of heart failure
hospitalization38.