P-wave configuration as an indicator of echocardiographic indices of cardiac structure and function in normotensive adolescents

We evaluated the associations of a bimodal P-wave in ECG lead V1 to cardiac structure and function in healthy normotensive adolescents. Two-dimensional-guided M-mode echocardiography, 12-lead ECG, and conventional and 2-hour averaged automated blood pressure (BP) measurements were obtained in 40 normotensive (conventional BP less than 140/90 mm Hg) adolescents (mean age, 13 +/- 1 years). Compared with subjects with simple unimodal P-waves (n = 18), those with a normal yet bimodal P-wave in lead V1 (n = 22) had higher two-hour averaged systolic BP (108 +/- 12 mm Hg vs 99 +/- 7 mm Hg, p less than 0.01) and conventional sphygmomanometer systolic BP (110 +/- 11 mm Hg vs 103 +/- 10 mm Hg, p = 0.05). Structurally, the bimodal P-wave group had greater left ventricular mass (174 +/- 40 g vs 144 +/- 26 g, p less than 0.01), and functionally, they had a greater stroke volume (68 +/- 15 ml vs 57 +/- 13 ml, p less than 0.05) than the unimodal P-wave group. In the group with bimodal P-waves, left atrial size was directly related to left ventricular mass (r = 0.63). By step-wise multiple linear regression analysis, this correlation coefficient increased to 0.74 with inclusion of heart rate and to 0.82 with inclusion of systolic BP. Although left atrial size was similar in the unimodal and bimodal P-wave groups, it was unrelated to any parameter in the unimodal P-wave group. Thus, a bimodal P-wave in lead V1, while generally considered a normal variant, is associated with slightly higher systolic BP, significantly greater left ventricular mass, and greater stroke volume. Additionally, a bimodal P-wave in V1 is predictive of the parameters that influence left atrial size, especially left ventricular mass. While all of these findings fall within the traditionally defined normal ranges, the existence of a bimodal P-wave might identify young individuals who are vulnerable to early cardiovascular manifestations of hypertension.