QTc Interval Prolongation Is a Proxy for Increased Short-Term Mortality

Abstract

BackgroundProlongation of the corrected QT (QTc) interval has been associated with increased long-term mortality; however, little is known about short-term mortality. This knowledge gap represents a clinical dilemma, because determining the disposition of patients with QTc prolongation is difficult. ObjectiveTo estimate the short-term (7-day and 30-day) all-cause mortality risk in patients with moderately and severely prolonged QTc. MethodsThe study-design was a Retrospective international multi-center observational cohort study, which took place in four emergency departments in Denmark and Sweden. Participants were all adult patients who received an ECG on arrival. QTc intervals were calculated with the Framingham formula. Associations between QTc duration and mortality were estimated with univariable and multivariable analyses, propensity score matching, and cubic splines analyses. ResultsAmong 103,075 ECGs, we identified 6672 (6.5%) patients with moderate and 587 (0.6%) with severe QTc prolongation. The crude hazard ratios (HRs) for moderate QTc prolongation (450/460−499 ms (men/women) were 2.2 (1.8-2.6) for 7-day and 2.1 (1.9-2.4) for 30-day mortality; HRs for severe QTc prolongation (≥500 ms) were 3.7 (2.4-5.7) and 3.4 (2.5-4.7), respectively. Adjustments led to attenuated estimates, with fully adjusted HRs for moderate QTc prolongation of 1.7 (1.4-2.0) for 7-day and 1.6 (1.4-1.8) for 30-day mortality; fully adjusted HRs for severe QTc prolongation were 2.6 (1.9-4.3) and 2.6 (1.9-3.5), respectively. Only a minority of patients with moderate (8.7% in Denmark and 15.1% in Sweden) and severe QTc prolongation (20.0% in Denmark and 22.7% in Sweden) died of possible, but not confirmed, cardiac cause.Our limitations were that we used the first ECG measured and an automated QTc calculation. We could not adjust for treatments carried out during admission. ConclusionsModerate and severe QTc prolongation was strongly associated with short-term mortality. However, QTc prolongation is likely a proxy for underlying disease rather than a direct contributor to mortality.

Prevalence and prognostic value of electrocardiographic abnormalities in hypokalemia: A multicenter cohort study

“…QTc prolongation, ST‐segment deviations, and T‐wave alterations are well‐established ECG‐derived markers for cardiovascular death, sudden death, and all‐cause mortality in the general population [41–46]. The majority of studies on the significance of such ECG abnormalities in acutely ill patients have focused on highly selected patient groups, for example, patients with pulmonary embolism [47, 48], whereas only few studies have investigated risk prediction in unselected acutely ill patients [14, 17]. Findings from this study add to evidence suggesting that the presence of ECG abnormalities at admission to the ED should increase medical awareness; however, the investigated ECG changes are not particularly useful in identifying hypokalemic patients at excess risk of adverse events, especially if [K + ] is <3.0 mmol/L.…”

“…The study patients were part of the Evaluation of Unknown Predictors of Electrocardiographic Changes, a Transnational Study, a retrospective cohort study of all adult patients at four EDs in Denmark and Sweden, who on clinical indication had an ECG recorded at arrival [14, 15]. In the present study, we included patients presenting to the EDs of Helsingborg General Hospital and Skåne University Hospital at Lund, Sweden, from January 1, 2010, to December 31, 2014, and at the EDs of the Hospital of South West Jutland and Odense University Hospital, Denmark, from March 1, 2013 to December 31, 2014.…”

Propranolol can correct prolonged QT intervals in patients with cirrhosis

“…Although fatal arrhythmias are not a common cause of death in patients with cirrhosis, the clinical benefits of improving long QTc intervals in patients with cirrhosis are uncertain. However, the prolongation of the QTc interval is closely related to the severity of cirrhosis and is a predictor of mortality in cirrhosis, especially in patients with gastrointestinal bleeding or those who have undergone transjugular intrahepatic portosystemic shunt placement or liver transplantation (Day et al, 1993;Biselli et al, 2019;Brabrand et al, 2020;Hela et al, 2020).…”