let actpders = ActivePresentation.Slides.Item(1).Shapes.Placeholders
if(actpders.Count > 0){
    switch (actpders.Item(1).PlaceholderFormat.Type){
        case ppPlaceholderTitle:
            actpders.Item(1).TextFrame.TextRange = "Title Text"
            break
        case ppPlaceholderCenterTitle:
            actpders.Item(1).TextFrame.TextRange = "Centered Title Text"
            break
        default:
            MsgBox ("There's no horizontal" + "title on this slide")
    }
}