Intravenous Citalopram and acute cardiac repolarisation: a pilot electrocardiographic monitoring study

Citalopram is associated with dose-dependent prolongation of cardiac repolarisation, and monitoring of Fridericia-corrected QT (QTcF) is recommended in patients with additional risk factors [1]. While most evidence concerns oral administration, data on acute QTcF changes following intravenous (i.v.) administration in psychiatric inpatients remain limited [2]. Repeated electrocardiographic (ECG) sampling may help characterise short-term, time-dependent effects [2,3].AimsThis exploratory pilot study aimed to describe short-term QTcF variability before and after administration of 20 mg i.v. citalopram in routine inpatient care, and to record any clinically relevant QTc prolongation or treatment-emergent cardiac events. The study was hypothesis-generating and not powered for statistical inference.MethodsThis observational ECG monitoring study was conducted in routine clinical practice. Four inpatients receiving 20 mg i.v. citalopram contributed analysable paired QTcF data across eight monitored infusion-days from treatment initiation. On each monitored day, a 12-lead ECG was recorded before infusion (T0), immediately after (T1), and 2 hours post-infusion (T2), yielding 24 recordings.The primary endpoint was the paired change in QTcF between T0 and T1. Secondary endpoints included QTcF change between T0 and T2, maximum post-infusion QTcF, Bazett-corrected QT (QTcB) as a sensitivity measure, and any treatment-emergent cardiac symptoms or discontinuations. Clinically relevant QTc prolongation was defined, in line with ICH E14 [3] and FDA labelling [1], as QTcF ≥500 ms or an increase ≥60 ms from baseline. Continuous variables were summarised as mean ± SD, median, and range. Paired changes were analysed using Wilcoxon signed-rank tests, presented as exploratory and uncorrected for multiple comparisons. No formal sample size calculation was performed.ResultsFive inpatients received i.v. citalopram; four contributed analysable paired QTcF data. Median age was 53 years (range 22–83), and three patients were male. Mean QTcF values were 354 ± 23.9 ms at T0, 377 ± 21.3 ms at T1, and 353 ± 25.8 ms at T2.The paired QTcF change from T0 to T1 was +23.1 ± 28.2 ms (median +36.5; range −25 to +58; p = 0.068), while the change from T0 to T2 was −1.1 ± 32.7 ms (median +1.5; range −45 to +51; p = 1.000). QTcB analyses showed a similar pattern. No QTcF value reached ≥500 ms, and no individual increase reached ≥60 ms. The maximum observed QTcF was 402 ms, and the largest individual increase was +58 ms. No arrhythmias, syncope, presyncope, palpitations, dizziness, or safety-related discontinuations were recorded.ConclusionsIn this small observational pilot study, 20 mg i.v. citalopram was associated with a transient increase in mean QTcF immediately after infusion, followed by return to baseline within 2 hours. No clinically relevant QTc prolongation or acute cardiac adverse events were observed.These findings should be considered hypothesis-generating, given the small sample size, repeated infusion-days within individuals, and lack of systematic control for potential confounders such as electrolytes, concomitant QT-prolonging medications, and baseline cardiac risk. Larger prospective studies with extended ECG monitoring are needed to better define the cardiac safety profile of i.v. citalopram in routine inpatient settings.

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