Although
flecainide and
verapamil have been used together successfully, serious and potentially life-threatening cardiogenic shock and asystole have been seen in a few patients. This is probably because the cardiac depressant effects of the two drugs can be additive.
The additive cardiac depressant effects are probably of little importance in many patients, but may represent the last straw' in a few who have seriously compromised cardiac function. Monitor concurrent use carefully.