One study suggests low doses of QTc prolonging meds are unlikely to cause TdP in your avg patient, but would be careful if QTc > 500 or patient/drug is higher risk.
3/4: Not all drugs are created equal!
Common antiarrhythmics are more likely to cause TdP. Other drugs have a risk, but most are only documented as case reports (PMID: 32929996)
4/4: Here’s my summary on QT prolonging medications categorized by risk for Torsades de Pointes