WPF - Making an animation's execution conditional on a property of the bound data item

I have a data object -- a custom class called Notification -- that exposes a IsCritical property. The idea being that if a notification will expire, it has a period of validity and the user's attention should be drawn towards it.

Imagine a scenario with this test data:

_source = new[] {
    new Notification { Text = "Just thought you should know" },
    new Notification { Text = "Quick, run!", IsCritical = true },
  };

The second item should appear in the ItemsControl with a pulsing background. Here's a simple data template excerpt that shows the means by which I was thinking of animating the background between grey and yellow.

<DataTemplate DataType="Notification">
  <Border CornerRadius="5" Background="#DDD">
    <Border.Triggers>
      <EventTrigger RoutedEvent="Border.Loaded">
        <BeginStoryboard>
          <Storyboard>
            <ColorAnimation 
              Storyboard.TargetProperty="Background.Color"
              From="#DDD" To="#FF0" Duration="0:0:0.7" 
              AutoReverse="True" RepeatBehavior="Forever" />
          </Storyboard>
        </BeginStoryboard>
      </EventTrigger>
    </Border.Triggers>
    <ContentPresenter Content="{TemplateBinding Content}" />
  </Border>
</DataTemplate>

What I'm unsure about is how to make this animation conditional upon the value of IsCritical. If the bound value is false, then the default background colour of #DDD should be maintained.