Is it time to leave diagnostics based on ejection fraction?

At first glance, left ventricular (LV) function may seem easy to understand, and most physicians are familiar with frequently used parameters such as ejection fraction (EF), stroke volume, and cardiac output. Although well known, these measurements do not necessarily provide a comprehensive measurement of LV function. - Smiseth, Aalen and Skulstad write in Heart failure and systolic function: time to leave diagnostics based on ejection fraction?.

The apparent discrepancy between global longitudinal strain (GLS) and ejection fraction (EF) is explained by EF being related predominantly to left ventricular (LV) circumferential shortening, whereas GLS measures longitudinal shortening. Since myofibres that account for longitudinal shortening are located mainly in the vulnerable subendocardium, reduction in GLS may precede reduction in LVEF. Furthermore, with concentric hypertrophy, which is common in HFpEF patients, there is typically a small LV cavity and therefore normal or supernormal EF even when stroke volume is reduced. A limitation of GLS, as well as of EF, is the marked afterload dependency. Additionally, reduced GLS is found in only ∼50% of HFpEF cases. Therefore, in a large fraction of HFpEF patients, GLS will not provide the information needed.

With the exception of antihypertensive therapy, there is essentially only symptomatic therapy available for patients with HFpEF. The exception is a few relatively rare phenotypes with specific therapies. The rather non-specific nature of HF symptoms and lack of unified diagnostic criteria for HFpEF are major limitations for clinical trials of medical therapies for HFpEF. A non-invasive method which can quantify LV pump function better than EF would be a major step forward. In this regard, LV global longitudinal strain (GLS), is more sensitive than LVEF for mild systolic dysfunction and is a useful supplementary method. Therefore, when patients with HF symptoms and normal LVEF have reduced GLS (<16%), it is likely that LV dysfunction contributes to their symptoms.