Tissue doppler echocardiographic assessment of right ventricular function in patients with acute inferior myocardial Infarction

ABSTRACT

Unlike left ventricular [LV] function, right ventricular [RV] function has not been widely studied after myocardial infarction [RVMI]. Furthermore, rapid, accurate, and widely available non-invasive evaluation of RV function still presents a problem. The purpose of this study was to determine whether parameters derived from tissue Doppler imaging [TDI] of tricuspid annulus could be used to detect RV infarction and so to assess RV function in patients with first acute inferior myocardial infarction [AIMI]. Patients and. We examined 27 patients with first AIMI admitted to CCU at El Minia University Hospital between March 2005 and October 2007, 12 with [group I] and 15 without ECG signs of RVMI [group II]. Twenty adults served as controls [group III]. Patients with any cardiovascular risk factor were excluded. Tissue Doppler Echocardiographic [TDE] study included recording of peak systolic [Sm], early diastolic [Em], late diastolic [Am] and [Em/Am] ratio of tricuspid annular velocities at 2 sites corresponding to the septum and RV free wall from apical 4 chamber view. Ejection time [ET], isovolumic relaxation time [IVRT], and isovolumic contraction time [IVCI'] were also recorded, then, Tie index [MPI] was calculated for each site. Standard echo Doppler study, electrocardiogram [ECG] and cardiac enzymes were also performed. Patients with AIMI had significantly reduced peak Sm, Em, Am and Em/Am ratio and increased IVRT, IVCT, ET and Tei index at the 2 sites especially at the RV free wall [infarction site] compared with healthy controls. At septal side of the tricuspid annulus, the peak Sm, Em, and Am were significantly reduced in group I compared with both group II, p=0.032. p<0.0001, p=0.001 respectively and group Ill, p<0.0001 for all velocities, with slightly significantly reduced velocities in group II compared with controls, p=0.012, 0.016, 0.030 respectively. The Sm/Am ratio was significantly decreased in group I compared with both group II, p<0.0001 and group Ill, p<0.0001 without significant difference between the latter two groups. While, the IVRT, IVCT, and ET were significantly increased in group I compared with both group II, p=0.004, 0.043, 0.005 and group Ill, p<0.0001, 0.0001, 0,026 respectively. Apart from ET, both of IVRT and IVCT were also increased in group II compared with group lII, p=0.03, 0.009. The septal MPI was significantly increased in both group I, p=0.002 and group II, 0.003 compared with controls without difference between both groups. On the other hand, at RV free wall, these myocardial velocities and Em/Am ratio were significantly reduced only in group I compared with both group 11, [p<0.0001 for all, p=0.029 for Em/Am ratio] and group Ill, [p<0.0001 for all, p=0.016 for Em/Am ratio] without significant difference between the latter two groups. While, IVRT, IVCT, ET, and RV MPI were significantly increased also only in group I compared with both group II, p<0.0001 for all and group Ill, p<0.0001 for all, without significant difference between the latter two groups. At Sm cutoff value of <12 cm/s, we were able to detect RVMI by 85% sensitivity, 93% specificity, 92% PPV, and 87% NPV, while at RV MPI >0.7, these were 92%, 100%, 100%, and 93% respectively. Systolic and diastolic myocardial velocities at the tricuspid annulus can be easily and quickly recorded by pulsed wave TDE. The decreased velocities and increased MPI seem to be an expression of regionally reduced myocardial function especially at the RV infarction site and so reflects RV systolic and diastolic dysfunction. Therefore, TDE can be used to assess RV systolic and diastolic function in patients with AIMI