Abstract Body (Do not enter title and authors here): Background: Acquired long QT syndrome is often underrecognized in critically ill patients, despite a high burden of contributing factors like electrolyte disturbances, medications, and comorbidities. However, its prognostic significance in this population remains insufficiently defined.
Objective: To determine prevalence, clinical characteristics, independent predictors, and ICU outcomes associated with QTc prolongation in critically ill adults.
Methods: In this prospective, single-center observational study (Jan–Jun 2024), we enrolled 245 consecutive adult ICU patients. QTc prolongation was defined as ≥450 ms in men and ≥460 ms in women; QTc ≥500 ms was considered markedly prolonged. Clinical profiles, labs, medication exposure, and outcomes were recorded. Multivariate logistic regression was used to identify independent predictors.
Results: Mean QTc was 479.7±56.9 ms. QTc prolongation was observed in 173 patients (70.6%), with 67 (27.3%) having QTc ≥500 ms. Prolonged QTc was significantly associated with heart failure (86.2%, p=0.003), shock (80.7%, p=0.013), and reduced LVEF (38.7% vs 45.7%, p=0.002). Electrolyte and biochemical abnormalities—including hypokalemia, hypocalcemia, hyponatremia, hypoalbuminemia, and elevated transaminases—were more prevalent in this group (all p<0.05). Medications such as amiodarone (85.1%), haloperidol (91.4%), furosemide (78.7%), levosalbutamol (45.6%) were significantly associated with QTc prolongation. Multivariate analysis identified heart failure [OR 3.4, 95% CI 1.2–9.2, p=0.015], amiodarone [OR 2.9, 95% CI 1.08–7.9, p=0.033], and haloperidol [OR 4.7, 95% CI 1.2–17.8, p=0.023] as independent predictors. Patients with prolonged QTc had longer ICU stay (median 6.5 vs 5 days, p=0.001) and higher incidence of ventricular tachycardia (94% vs 6%, p=0.004), though ICU mortality did not differ significantly (p=0.732).
Conclusion: QTc prolongation is significantly associated with adverse clinical outcomes, arrhythmic events, and longer ICU stay. Its high prevalence in this setting, makes this a common finding in critically ill patients and raises important questions regarding how strongly it should influence risk stratification and clinical decision-making. Routine QTc monitoring, particularly in patients with heart failure or exposure to QT-prolonging medications and in those with QTc >500ms may enhance early identification of high-risk individuals and proactive management strategies to mitigate cardiovascular complications.