Natural History of Myocardial Function in Adults
What are the determinants of aging-related left ventricular (LV) remodeling and function in a large multiethnic population?
The investigators examined 757 participants who were free of clinical cardiovascular disease and underwent tagged cardiac magnetic resonance both at baseline and at the 10-year follow-up as part of the MESA (Multi-Ethnic Study of Atherosclerosis) study. LV remodeling, circumferential shortening (CS), and torsion were assessed by tagged cardiac magnetic resonance. Multivariable linear regression was used to determine the association of changes in risk factors with changes in cardiac geometry and function.
The mean age of participants was 63 ± 9 years at baseline; 50% were women. Overall, the LV mass-to-volume ratio increased by 10% over 10 years (p < 0.01). CS was unchanged (17.8%-17.9%, p = 0.246), whereas torsion increased by 13% (3.8º/cm to 4.3º/cm, p < 0.001). Increased systolic blood pressure was associated with reduced CS (-0.02%/mm Hg, p < 0.01). Participants who remained on antihypertensive therapy during the whole study had a greater decrease in LV mass-to-volume ratio (-0.045 vs. no medication, p < 0.05) with a greater increase in CS (0.78% vs. no medication, p < 0.01). Moreover, greater LV mass at baseline was significantly associated with reduced CS (-0.02%/g, p < 0.01) and torsion (-0.02º/cm/g, p < 0.01) independently of risk factors.
The authors concluded that longitudinal observation demonstrates that LV mass and worsening risk factors are fundamental determinants of reduced regional myocardial shortening over 10 years.
This study reports that over the second half of the adult human lifespan, increased LV mass, male sex, increased blood pressure, increased heart rate, and reduced high-density lipoprotein cholesterol are associated with reduced CS. However, individuals who remained on antihypertensive therapy during the entire follow-up study period maintained or improved myocardial shortening. Furthermore, increased torsion may be a key compensation mechanism to counter adverse remodeling alterations and maintain systolic function in association with aging. Overall, these observations suggest that controlling traditional risk factors is important to prevent reduction of LV systolic function.
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