DRUGS AND QTc INTERVAL DISPERSION

The measure of delayed ventricular repolarization most frequently used clinically is the ability of the new chemical entity to prolong the QTc interval on surface electrocardiogram. Intramyocardial dispersion of repolarization appears to play a more important role both in electrical stability of the ventricles and in arrhythmogenesis. The potential importance of myocardial dispersion of refractoriness in arrhythmogenesis has led to a number of attempts to assess it from the surface electrocardiogram. The QTc interval dispersion is the difference between maximal and minimal QTc intervals obtained from 12 electrocardiographic leads. Drugs which prolong QTc interval have different effect on QTc interval dispersion. Beta blockers decrease QTc interval and QTc dispersion. Amiodarone and sotalol increase QTc inerval but decrease QTc dispersion. Quinidine and flecainide increase QTc interval and QTc interval dispersion. Propafenone increases QTc interval dispersion in patients with myocardial ishemia. Treatment of patients with drugs which can improve inhomogenous ventricular repolarization leads to better prognosis. We should consider this more seriously when prescribing drugs.