Looks like a ~21% increase in risk over the metoprolol for diltiazem doses > 120 mg and ~14% increase for lower doses.
Patients receiving diltiazem treatment had increased risk for the primary outcome (RD, 10.6 [95% CI, 7.0-14.2] per 1000 PY. In absolute terms, a 1.06% risk per person year. For metoprolol, the risk would be 21% less or 0.79 x 1.06% = 0.84% risk per person year. A difference, yes. However the absolute risk is low to begin with.