Left ventricular regional wall motion assessment in myocardial infarction by phase analysis

Kim, Eun Young; Choe, Kyu Ok; Park, Chang Yun; Kim, Myeong Jin; Cho, Seung Yun

Abstract

BACKGROUND
In patients with myocardial infarction, one needs to know the location, extent and severity of wall motion abnormalities to assess prognosis and guide therapy. Thus more precise quantatative estimates of regional ventricular function are required. Regional wall motion has generally been assessed by displaying the multiple cardiac images of RVG as endless-loop movie, but the cinematic display was not objective. We used the usefulness of the phase analysis in evaluating the global left ventricular function and regional wall motion abnormalities of patients with myocardial infarction. The accuracy of the RVG cinematic display in detecting regional wall motion abnormalities in patients with myocardial infarction was also evaluated. METHODS: Studied cases were 97 patients with myocardial infarction and 20 normals with low likelihood of coronary artery disease. Coronary angiography and contrast left ventriculography were performed in all patients with myocardial infarction. The regional wall myocardial infarction(presence) is defined when the EKG presented the evidence of myocardial infarction, left ventriculogram showed RWMA(regional wall motion abnormality) along with stenosis of 50% or greater of the regional supplying coronary artery. Each patient was imaged in 45 left anterior oblique(LAO) view, anterior(Ant) view and left lateral(Lt Lat) view. We evaluated Left ventricular ejection fraction(LVEF) from time-activity curve. We constructed the histogram for the left ventricle and both ventricle separately to obtain the global and total phase angle(GPA, TPA), standard deviation of phase angle(GSDPh, TSDPh), full width half maximum(GFWHM, TFWHM). The left ventricle was divided into 7 segments. LAO projection ; septal, apical, basal lateral, apical lateral, Ant projection ; anterolateral, Lt Lat projection ; inferior, posterior, Phase angle(RPA) and full width half maximum(RFWHM) from the histogram (regional 7 segments) were examined. On the RVG cinematic display, the standard 4 grading system was used, normal, hypokinesia, akinesia, dyskinesia. The observer evaluated regional wall motion abnormality of the 7 segments for all cases. The sensitivity of the above parameters and RVG cinematic display was evaluated. We analyzed the regional parameters among the patents with regional wall myocardial infarction(presence), those without regional wall myocardial infarction(absence) and control group using the t-test. The statistical analysis was done by one way ANOVA between regional phase analysis and RVG cinematic display. RESULTS: The sensitivity of LVEF was lowest(70.1%) and the GFWHM was highest among the global parameters(89.1%). But RFWHM showed even higher sensitivity(96.9%), thus regional phase analysis was also required. The RVG cinematic display was also sensitive(92.7%), but less sensitive than the RFWHM. On regional phase analysis the RPA of septal, apical, inferior, posterior walls of the left ventricle was able to separate presence group from absence group and also presence group from control group and the RPA of the apical lateral wall could separate presence group from absence group. The RPA of basal lateral and anterolateral wall was inaccurate in diagnosing the regional wall myocardial infarction, because basal lateral wall was overlapped by adjacent vascular structures, and the area of anterolateral wall dose not correlate completely beteen the RVG & the left ventriculogram, also the anterolateral wall can be supplied by the obtuse marginal branch of left circumflex artery. The RFWHM of all regional walls of left ventricle could separate presence group from absence group and presence group from control group. We found good correlation between regional phase analysis & left ventriculogram for detection of regional wall myocardial infartion. On RVG cinematic display, the RPA of the normal group was different from that of dyskinesia, akinesia and hypokinesia groups. The RPA of the dyskinesia group was also different from that of skinesia and hypokinesia groups by oneway ANOVA(p<0.05). The RFWHM of the dskinesia group was different from that of the normal group and hypokinesia group. RVG cinematic display correlated well with regional phase analysis and also quantitation of wall motion. CONCLUSIONS: Thus RVG cinematic display was useful and can not be replaced by phase analysis. But the regional phase analysis was sensitive and objective in diagnosing the wall motion abnormality in myocardial infarction.