Drug-Induced Prolonged QT in the U.S.

Drug induced QT prolongation in the US ¹

• 12,000+ cases annually of drug induced TdP in the US
• 66% of cases occur in females
• 100% of patients had at least 1 risk factor, 71% had 2 risk factors

LQTS risk factors²

• Female
• Age 65+ years
• Bradycardia
• Congenital LQTS
• Heart failure
• Heart block
• Myocardial infarction
• Genetic polymorphisms

TdP symptoms³

• Heart palpitations 
• Dizziness
• Nausea
• Cold sweats
• Chest pain
• Shotness of breath
• Low blood pressure
• Bradycardia

Drugs associated with QT prolongation⁴

• Antiarrhythmics
• Antidepressants
• Antimicrobials
• Antipsychotics

Drugs are the greatest risk of QTc prolongation

QTc>500 ms increases risk of TdP. ⁵ Each 10 ms increase, increases a 5-6% the risk of TdP. ⁵

Preventing Tordades de Pointe (TdP)⁶

1. Assess the patient
   1. History
   2. Symptoms of TdP
2. Assess the therapy
   1. Drugs & doses
   2. ECG (if risk factors)
3. Take action
   1. QT interval monitoring
   2. Adapt therapy

References:

1. https://www.ahajournals.org/doi/10.1161/CIR.0000000000000558 
2. https://www.uspharmacist.com/article/medication-induced-qtinterval-prol…;
3. https://www.medicalnewstoday.com/articles/320619.php 
4. https://crediblemeds.org/new-drug-list/ 
5. Sauer, A. J., et al. (2007). "Long QT syndrome in adults." J Am Coll Cardiol 49(3): 329-337. 
6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4860754/