What can cause QT prolongation?

There are many factors that predispose to QT prolongation including, e.g. age, female gender, left ventricular hyperthrophy, heart failure, myocardial ischaemia, hypertension, diabetes mellitus, increased thyroid hormone concentrations, elevated serum cholesterol, high body mass index, slow heart rate and electrolyte …

What electrolyte causes prolonged QT?

Background: Prolonged QTc (corrected QT) interval and torsades de pointes (TDP) are associated with hypocalcemia, hypomagnesemia, hypokalemia, possibly alkalosis and may result in syncope and sudden cardiac death.

What is a prolonged QTc?

QTc is prolonged if > 440ms in men or > 460ms in women. QTc > 500 is associated with an increased risk of torsades de pointes. QTc is abnormally short if < 350ms. A useful rule of thumb is that a normal QT is less than half the preceding RR interval.

Who is at risk for QT prolongation?

Factors that predispose to QT prolongation and higher risk of torsades de pointes include older age, female sex, low left ventricular ejection fraction, left ventricular hypertrophy, ischemia, slow heart rate, and electrolyte abnormalities including hypokalemia and hypomagnesemia.

What medications cause torsades?

Other drugs that prolong the QT interval and have been implicated in cases of torsade include phenothiazines, tricyclic antidepressants, lithium carbonate, ziprasidone, cisapride, highly active antiretroviral drugs, high-dose methadone, anthracycline chemotherapeutic agents (eg, doxorubicin, daunomycin), some …

Why hypocalcemia causes QT prolongation?

Hypocalcaemia is a recognised cause of QT prolongation via prolongation of the plateau phase of the cardiac action potential. This causes calcium ion channels to remain open for a longer period, allowing a late calcium inflow and the formation of early after-depolarisations.

Does hypokalemia cause prolonged QT interval?

Hypokalemia is another common risk factor in drug-induced LQTS. Low extracellular potassium paradoxically reduces IKr by enhanced inactivation [42] or exaggerated competitive block by sodium [43]. As a result, hypokalemia prolongs the QT interval.

How do I lower my QTC?

Beta blockers used to treat long QT syndrome include nadolol (Corgard) and propranolol (Inderal LA, InnoPran XL). Mexiletine. Taking this heart rhythm drug in combination with a beta blocker might help shorten the QT interval and reduce your risk of fainting, seizure or sudden death.

What are the risks with prolonged QTc?

An abnormally prolonged QTc interval (>450 ms in men, >470 ms in women) was associated with a three-fold increased risk of sudden cardiac death (hazard ratio, 2.5; 95\% confidence interval, 1.3 to 4.7), after adjustment for age, gender, body mass index, hypertension, cholesterol/high-density lipoprotein ratio, diabetes …

Does lithium cause prolonged QTc?

Mood stabilizers. Among the mood stabilizers, lithium[22] has a moderate risk of QTc prolongation while the antiepileptics used for this purpose such as carbamazepine, oxcarbazepine, topiramate, valproate,[26] pregabalin, gabapentin,[27] and lamotrigine[28] are reported to be safe with a low risk of QTc prolongation.