Excessive D2 receptor blockade can lead to which of the following cardiac concerns?

Excessive D2 receptor blockade is known to interfere with the normal cardiovascular function, particularly through the effects on cardiac repolarization. Dopamine receptors, specifically the D2 subtype, play a crucial role in modulating various pathways in the heart. When D2 receptors are excessively blocked, it can lead to a disruption in the electrical activity of the heart, resulting in QT prolongation.

QT prolongation is significant because it increases the risk of developing life-threatening arrhythmias such as Torsades de Pointes, which can lead to syncope or sudden cardiac death. This phenomenon is particularly associated with the use of certain antipsychotics and other medications that block dopamine receptors.

While bradycardia and myocardial infarction can be serious cardiac events, they are not directly linked to D2 receptor blockade in the same way that QT prolongation is. Ventricular hypertrophy may be related to long-term stress on the heart but is not an immediate effect of D2 receptor antagonism. Therefore, the most relevant cardiac concern resulting from excessive D2 receptor blockade is specifically QT prolongation.