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

## TL;DR

This study found that one-third of ICU patients in Pakistan had prolonged QTc intervals, which were linked to sepsis, kidney issues, and certain medications, increasing the risk of complications and death.

## Contribution

This is the first multicenter study in Pakistan to investigate QTc prolongation in ICU patients and identify its predictors.

## Key findings

- QTc prolongation occurred in 32% of ICU patients, with higher rates of sepsis and kidney injury in affected individuals.
- Prolonged QTc was associated with longer ICU stays and significantly higher mortality rates.
- Septic shock, renal dysfunction, and haloperidol use were identified as independent predictors of QTc prolongation.

## Abstract

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.

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.

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).

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.