Introduction:
The myocardial contraction fraction (MCF), the ratio of LV stroke volume (SV) to myocardial volume (MV), is a volumetric measure of myocardial shortening. With 3D-echocardiography and MRI, MCF distinguished pathologic from physiologic hypertrophy and predicted incident CV events. However, the association between 2D echo-determined MCF and adverse CV outcomes is not known, nor has the premise that this ratio adequately captures the predictive information of its components, SV and MV, been tested.
Methods:
Using CHS data, we calculated MCF from 2-D guided M-mode echo dimensions to estimate LV volumes and SV. MV was estimated from the measurements of LV mass divided by myocardial density. Among individuals with a normal EF, Cox regression was used to examine the associations between MCF with incident heart failure (HF), cardiovascular disease (CVD), and all-cause mortality adjusting for clinical and echo parameters. We further examined the validity of the premise that log(SV) and log(MV) contribute in the expected ratio of 1: -1 with our outcomes of interest.
Results:
1556 participants were identified with an EF ≥ 55% (age 72±5) that had baseline echo data and available covariate information. MCF averaged 58% (Range: 21-104%). After controlling for CV, clinical risk factors, echo variables and NT-proBNP, a 10% relative increase in MCF was significantly associated with reduced risk of HF, CVD and death. When included separately in the models, both MV and SV showed significant associations with CVD and death, however, only MV was significant for HF and the coefficients violated the 1:-1 ratio suggesting MCF is not the best way to model this relationship.
Conclusions:
Among older adults with normal EF, 2D-echo MCF was associated with a lower risk of adverse CV outcomes after adjustment for clinical factors, echo parameters, and NT-proBNP. However, MCF compared to its component measures might be inadequate for risk prediction in HF.
Association of Blood Pressure Trajectory With Mortality, Incident Cardiovascular Disease, and Heart Failure in the Cardiovascular Health Study
