Statistical details :
The ability of ordinal variables (E/A, S/D, E/Vp) to predict PCWP was tested for previously determined cutoffs as per extant guidelines. Based on diastolic function guidelines4, sensitivity and specificity were calculated for prefixed cutoff values i.e.,(E/A<1, E/A1-2, E/A>2, S/D<1 & E/Vp>2.5). For continuous data, optimal cut off values were determined by constructing ROC curves i.e., for echocardiographic variables ( SF, E/Ea, DT).
As per new revision of diastolic function guidelines 201616, evaluation of diastolic function should proceed on different lines in patients with normal versus depressed left ventricular systolic function because of high prevalance of diastolic dysfunction in the latter. Accordingly, when the pretest probability of diastolic dysfunction is much higher in patients with systolic dysfunction, any attempt to distinguish presence or absence of diastolic dysfunction should stress on specificity.
For patients with normal systolic function, cut off values using ROC curve analysis were calculated by focusing on sensitivity. So, for variables (SF, E/Ea, DT), cut off values were calculated based on both maximizing sensitivity and specificity. In all the cases, validity parameters such as sensitivity, specificity, predictive value of positives, predictive value of negatives & accuracy were computed.