QTc interval prolongation in ICU patients: risk assessment and predictors.

BACKGROUND

Prolonged corrected QTcs are a frequent and potentially life-threatening finding In ICU patients, the presence of prolonged QTc is a prevalent and potentially life-threatening condition, as it increases the risk of TdP and sudden cardiac death. Risk factors include sepsis, electrolyte imbalances, and QTc-prolonging drugs. However, data from South Asian ICUs remain limited.

METHODS

We conducted a 12-month prospective observational study in two tertiary care ICUs in Lahore and Karachi, enrolling 812 adult patients without pre-existing QTc abnormalities. QTc was calculated using Bazett’s formula, with prolongation defined as QTc ≥ 450ms (men) or QTc ≥ 470 ms (women). Clinical, biochemical, and pharmacologic data were collected. Multivariate logistic regression identified independent predictors of ICU-acquired QTc prolongation.

RESULTS

QTc prolongation occurred in 260 (32.0%) patients. These individuals had higher rates of sepsis (55%), acute kidney injury (45%), and electrolyte disturbances (hypokalemia 35%, hypomagnesemia 30%). QTc-prolonging medications, particularly haloperidol (22%), were more common among cases. Septic shock, coronary artery disease, renal dysfunction, and haloperidol were significant independent predictors. Prolonged QTc was associated with longer ICU stays (median 10 vs. 5 days) and higher mortality (45% vs. 18%, p < 0.001).

CONCLUSION

In this inaugural multicenter study conducted in Pakistan, it was observed that one-third of patients in the ICU experienced QTc prolongation, which was associated with sepsis, renal dysfunction, and the administration of specific medications. These findings underscore the importance of QTc monitoring, electrolyte management, and cautious drug selection to reduce arrhythmia-related complications.