Right ventricular stunning in inferior myocardial infarction

To assess right ventricular (RV) function in patients with inferior myocardial infarction (IMI) and to observe changes following thrombolysis.

RV dysfunction occurs in 30% of patients with IMI. The extent of such involvement and its potential, recovery has not been determined.

We studied 30 patients with acute IMI (age 56+/-12 years), on admission, day 7 and day 30 post thrombolysis. No patient had clinical signs of RV failure. RV segmental function was assessed from free wall long axis and global function from filling and ejection velocities. Values were compared with 15 age-matched controls.

On admission, RV long axis amplitude, systolic and diastolic velocities were depressed (2.09+/-0.39 vs 2.6+/-0.3 cm, 8.18+/-1.8 vs 10.0+/-2.0 cm/s and 6.9+/-2.7 vs 10.0+/-2.5 cm/s, p<0.01 for all) and global function impaired; reduced Z ratio (0.85+/-0.07 vs 0.9+/-0.04, p<0.01), raised Tei index (0.49+/-0.26 vs 0.3+/-0.1, p<0.001) and prolonged t-IVT (8.16+/-3.9 vs 4.8+/-2 s/m, p<0.01) compared to controls. After thrombolysis, RV long axis amplitude (2.28+/-0.3 cm, p<0.05), systolic velocity (10.0+/-2.7 cm/s, p<0.01), early diastolic velocity (8.3+/-2.16, p<0.05), Z ratio (0.9+/-0.05, p<0.01), Tei index (0.34+/-0.17, p<0.01) and t-IVT (6.2+/-2.7 s/m, p<0.05) all normalised at day 30. Only 4 (13%) patients remained with RV long axis amplitude and one with t-IVT and Tei index values outside the normal 95% CI at day 30. RV inflow diameter and tricuspid regurgitation did not change.

In IMI, RV segmental and global functions are acutely impaired, and recover in 87% of patients following thrombolysis. In the absence of clear evidence for RV infarction the disturbances in the remaining 13% may represent stunned myocardium that may demonstrate delayed recovery.