Low-dose dobutamine echocardiography predicts recovery of left ventricular systolic function following revascularization even in presence of low contractile reserve.

BACKGROUND: Coronary revascularization is known to improve left ventricular ejection function (LVEF) in patients with severe left ventricular systolic dysfunction if there is myocardial viability and contractile reserve is >40% as determined by low-dose dobutamine echocardiography (LDDE). We tried to assess effect of coronary revascularization on left ventricular systolic function in patients with low contractile reserve (40%).

METHODS AND RESULTS: In a retrospective analysis we studied 114 consecutive patients with left ventricular systolic dysfunction (LVEF <40%) with low contractile reserve (<40%) as detected by LDDE (16-segment model). Contractile reserve was defined as number of dysfunctional segments that improved on LDDE divided by total number of left ventricular segments studied. Dysfunctional segments at baseline that improved on low-dose dobutamine were considered viable. On the basis of presence or absence of viability and treatment modality, patients were grouped as: revascularization with viability-group A; revascularization without viability-group B; medical therapy with viability-group C, and; medical therapy without viability-group D. At subsequent follow-up (3 months, 1 year and 2 years) left ventricular systolic function was assessed by LVEF and wall motion score index (WMSI). Improvement in left ventricular systolic function was considered to have occurred only if both LVEF and WMSI showed statistically significant ( p<0.05) improvement from baseline. The mean LVEF in viable and non-viable groups were 33.3 -/+ 6.8% and 30.3 -/+ 7.1%, respectively. In patients with viability, the mean number of dysfunctional segments that improved at LDDE was 3.4 -/+ 1.7 and mean contractile reserve was 21.1 -/+ 17.8%. At LDDE, significant improvement in LVEF was seen in all four groups; however, significant improvement in WMSI was seen only in those with viability. At subsequent follow-up (3 months, 1 year and 2 years), significant improvement in LVEF and WMSI as compared to baseline was evident in group A alone. At two years, although the improvement in WMSI was of borderline significance (p = 0.05), the improvement in LVEF was significant ( p < 0.05). No significant improvement was seen in LVEF and/or WMSI in groups B, C and D.

CONCLUSION: Presence of myocardial viability on LDDE predicts recovery of left ventricular systolic function even in patients with low contractile reserve which is maintained at long-term follow-up, following revascularization.