Comparison of electrocardiographic and vectorcardiographic planes on a set of left ventricular hypertrophy patients

Abstract

Most common electrocardiographic diagnostic criteria for left ventricular hypertrophy (LVH) are based on depolarization information. However, reports support that LVH also alters repolarization. Two measures relate depolarization/ repolarization: the angle between the QRS-complex and the T-wave in a plane; the planar QRST (QRST p) and the vector obtained from the cross sum of the depolarization and repolarization vectors (RTa and RTm). We compared the performance of these measures as hypertrophy markers in two sets of planes: the ECG frontal plane (FP) versus the VCG frontal plane (XYP) and the ECG horizontal plane (HP) versus the VCG horizontal plane (XZP). The horizontal views picked up a significant increase of the QRSTp (HP controls vs LVH: 40.18±41.20° vs 66.50±51.65°, p<0.05; XZP controls vs LVH: 43.87±39.76° vs 66.35±38.30°, p<0.05) and a consistent behaviour in the frontal views (XYP controls vs LVH: 17.71±37.23° vs 35.60±47.98°, p<0.005). On the other hand, the angle of the equivalent RT vector significantly increased in the HP (HP controls vs LVH: 24.28±26.50° vs 33.53±22.42°, p<0.05). In conclusion, the angular information in their two forms (QRSTp and RTα) relating depolarization and repolarization was the most informative parameter and should be regarded for the construction of more sensitive electrocardiographic LVH indexes.