Contraindicated if the QTc interval is >450 ms. CrCl should be calculated before dosing. If CrCl >60 mL/min, then dosing frequency is twice daily. If CrCl 40 60 mL/min, dosing interval is every 24 h. If CrCl <40 mL/min, should not be used.) 160 mg every 12 h (During initiation and titration, the QT interval should be monitored 2 4 h after each dose. If the QT interval prolongs to 500 ms, the dose must be reduced or the drug discontinued.) QT prolongation, torsades de pointes, bradycardia, bronchospasm Prolonged QT Renal dysfunction Hypokalemia Diuretic therapy Avoid other QT-prolonging drugs Sinus or AV nodal dysfunction (in absence of pacemaker) Decompensated systolic HF Cardiogenic shock Reactive airway disease Drugs with SA and/or AV nodal blocking properties Table 7. Continued Drug Initial Daily Dose(s) Maximum Total Daily Maintenance Dose Potential Adverse Effects Precautions (Exclude or Use With Caution) and Interactions Page et al 2015 ACC/AHA/HRS SVT Guideline e531 patients with MAT who do not have ventricular dysfunction, sinus node dysfunction, or AV block227,228 ; although diltiazem has not been studied, it may provide a class effect with similar mechanism to verapamil. Beta blockers can be used with cau- tion to treat MAT in the absence of respiratory decompensa- tion, sinus node dysfunction, or AV block.229,230 Amiodarone has been reported to be useful in 1 report.231 Cardioversion is not useful in MAT.223 4.2.1. Acute Treatment: Recommendation 4.2.2. Ongoing Management: Recommendations 5.Atrioventricular Nodal Reentrant Tachycardia See Figure 12 for the algorithm for acute treatment of AVNRT and Figure 13 for the algorithm for ongoing management of AVNRT. AVNRT is the most common SVT. 