Can isovolumic acceleration be used in clinical practice to estimate ventricular contractile function? Reproducibility and regional variation of a new noninvasive index.

BACKGROUND

Myocardial acceleration during isovolumic contraction (IVA) has been validated as a relatively load-insensitive noninvasive index of contractility. Its feasibility, reproducibility, and variation between segments have not been studied in detail, and thus its utility in clinical practice has not been established.

METHODS

We analyzed myocardial velocity loops (median frame rate 182 s(-1)) from 20 young volunteers (10 men, aged 25.7 +/- 2.9 years), 20 patients with type 2 diabetes (14 men, aged 64.1 +/- 8.5 years), and 20 patients with heart failure (17 men, aged 64.6 +/- 7.7 years). Long-axis IVA was measured in all walls at the annulus and in basal and mid-ventricular segments. Intraobserver reproducibility for 1 observer in all subjects and interobserver reproducibility among 3 observers in 10 subjects from each group were assessed.

RESULTS

In control subjects, subjects with diabetes, and subjects with heart failure, the feasibility of measuring IVA was 97%, 89%, and 82%, respectively; intraobserver reproducibility was 12%, 18%, and 30%, respectively (pooled coefficients of variation); and mean interobserver reproducibility was 23%, 21%, and 28%, respectively. IVA was lower in the mid-ventricular segments by 24% to 43% compared with the annulus, and IVA was higher in the right than the left ventricle (P < .001). IVA of the medial mitral annulus discriminated those with heart failure from those with diabetes and controls, and had acceptable intraobserver reproducibility across groups (mean coefficient of variation 13%).

CONCLUSION

IVA may be used as a research tool if it is measured at the medial mitral annulus, but its clinical applicability is hampered by low reproducibility, especially in patients with impaired left ventricular function in whom it would otherwise be most useful.