Clinical significance of body surface mapping for a diagnosis of left ventricular hypertrophy : Special reference to a differential diagnosis between hypertrophic cardiomyopathy and hypertension-induced left ventricular hypertrophy

The present study was conducted to clarify electrophysiological characteristics of left ventricular hypertrophy (LVH) and to discriminate hypertrophic cardiomyopathy (HCM) from hypertension-induced LVH with body surface mapping. QRS area map, QRST area map and VAT map of body surface mapping were recorded on 37 patients with HCM, 37 with essential hypertension (EH) and 21 with aortic regurgitation (AR) using Yamada's method. HCM, EH and AR showed similar patterns of QRS area map. However, the maximum points of QRST area map located at the midsternal line (E5) in HCM, and positioned on the left midclavicular line (G4) in EH and AR. The minimum point of the QRST area map appeared at the left midclavicular line (G3) where the maximum point of the QRS area map was located. These findings indicate that the QRST area map would enable to differentiate HCM from EH and AR. With the VAT map, AR showed closed isochrone lines on the left precordium, which indicated delayed ventricular activation in this region. Statistical analysis revealed that the value of the maximum point of the QRST area (Max. QRST) and the sum of values of the positive QRST area (∑ positive QRST area) differentiates HCM from EH. When the Max. QRST was 0.6μVs or less and the ∑ positive QRST area was 14μVs or less, the diagnostic accuracy of HCM could be made more than 70%. These findings suggested that the diagnostic criteria derived from the QRST area map is of use to distinguish HCM from hypertension-induced LVH