Diltiazem in the Treatment of Atrial Fibrillation or Atrial Flutter With Rapid Ventricular Rate

To compare the relative efficacy for calcium pre-treatment in decreasing incidence of drug induced hypotension after diltiazem administration for treatment of AFF with RVR.Null Hypothesis: There will be no difference between groups in incidence of hypotension after pretreatment with calcium prior to bolus of diltiazem.

Inclusion Criteria:Age > 18 years or olderAble to provide informed consentPrimary diagnosis AFF with RVR greater than or equal to 120 bpmExclusion Criteria:Pregnancy defined as a positive urine HCGHemodynamically unstable patients (SBP <90, MAP <65)Stated history of systolic heart failure with reduced ejection fraction (<40%) or evidence of acute heart failure or reduced EF (peripheral edema, JVD, pulmonary edema) on clinical exam or bedside echoPatients with left ventricular assist deviceSinus node dysfunction or preexcitation with accessory pathway (known diagnosis of SVT, WPW or sick sinus syndrome. Delta waves or other evidence of accessory pathway on EKG)2nd or 3rd degree atrioventricular blockAllergy or sensitivity to any study drugsPreviously enrolled in this trial during a different patient encounterNon-English speaking