There's simpler solution for that - set fixed height of card elements - header and body. This way, we can set resposive layout with standard boostrap column grid.
Here is my example: http://codeply.com/go/RHDawRSBol
<div class="card-deck text-center">
<div class="col-sm-6 col-md-4 col-lg-3">
<div class="card mb-4">
<img class="card-img-top img-fluid" src="//placehold.it/500x280" alt="Card image cap">
<div class="card-body" style="height: 20rem">
<h4 class="card-title">1 Card title</h4>
<p class="card-text">This is a longer card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
<p class="card-text"><small class="text-muted">Last updated 3 mins ago</small></p>
</div>
</div>