Interatrial block and P-terminal force: A reflection of echocardiographic severity of mitral stenosis on ECG

Interatrial block (IAB), frequently overlooked conduction delay between the atria. IAB is simply defined as prolonged P waves (?110 ms). Importance of IAB and P terminal force as reflection of echocardiographic severity in rheumatic mitral stenosis has not been established so far. Our purpose was to test hypothesis that IAB with P terminal force can be used as reflection of echocardiographic severity of mitral stenosis on ECG. Patients with rheumatic mitral stenosis referred to a single cardiac center for echocardiography between July 2009 and October 2009, and who met the entry criteria for the study, were invited to participate. We prospectively studied 116 consecutive patients with echocardiography documented rheumatic mitral stenosis (mean age 39±11) were enrolled to the study. Age/gender matched 92 subjects without echocardiographic signs of rheumatic valve involvement were used as controls (mean age 37±11). For increased specificity, P wave ?120 ms was used to diagnose significant IAB. P-terminal force biphasic P in lead V1 ? area of 1 small square on the electrocardiogram was used as criterion to diagnose IAB. We echocardiographically analysed 116 patients with mitral stenosis and 92 normal subjects. There is no difference in terms of ages and gender beween two groups. Statisticallly positive correlation were present between IAB (?120ms) and mean mitral valve gradient (R=0.3, p<0.001). Statistically strong negative correlation were present between mitral valve area and presence of IAB (?120ms) (R=-0.3, p<0.001). Presence of, pulmonary hypertension and poor functional NYHA class were associated with high incidence of significant IAB (R=0.4, p<0.001; R=0.3, p<0.001, respectively). There were statistically strong correlation between IAB (?120ms) and P terminal force (p<0.001). Subgroup analysis in view of the presence valve calcification revealed that both of the presence of significant IAB and P terminal force were correlated with calcific mitral valve (p<0.001). Only mitral valve area (ß=0.3; p=0.008) was predictor of IAB in multivariate analysis. We demonstrated that severe mitral gradient, decreased mitral valve area, increased pulmonary hypertension, and poor NYHA class are predicted with significant IAB and P terminal force. Significant IAB (?120ms) and P terminal force might be considered as novel indicator of echocardiographic severity and associated complication during follow-up of mitral stenosis.Key words: Mitral stenosis, Echocardiography, Interatrial block, P wave terminal force.