Incidence and outcomes of long QTc in acute medical admissions

Abstract

SummaryAimsProlonged QT interval on electrocardiogram (ECG) increases the risk of ventricular arrhythmia. Patients admitted to acute medical units (AMU) may be at risk of QT prolongation from multiple, recognised risk factors. Few data exist regarding incidence or outcomes of QT prolongation in acute general medical admissions.The aims were to determine the incidence of Bazett's‐corrected QT (QTc) prolongation upon admission to AMU; the relationship between QTc and inpatient mortality, length of stay and readmission; proportion with prolonged QTc subsequently administered QT interval‐prolonging drugs.MethodsRetrospective, observational study of 1000 consecutive patients admitted to an AMU in a large urban hospital. Exclusion criteria: age <18 years, ventricular pacing, poor quality/absent ECG . QTc determined manually from ECG obtained within 4‐hours of admission. QTc prolongation considered ≥470 milliseconds (males) and ≥480 milliseconds (females). In both genders, >500 milliseconds was considered severe. Study end‐points, (a) incidence of QTc prolongation at admission; (b) inpatient mortality, length of stay and readmission rates; (c) proportion with QTc prolongation subsequently administered QT interval‐prolonging drugs.ResultsOf 1000 patients, 288 patients were excluded, therefore final sample was n = 712. Patient age (mean ± SD) was 63.1 ± 19.4 years; females 49%. QTc prolongation was present in n = 50 (7%) at admission; 1.7% had QTc interval >500 ms. Of the 50 patients admitted with prolonged QTc, 6 (12%) were subsequently administered QT interval‐prolonging drugs. QTc prolongation was not associated with worse inpatient mortality or readmission rate. Length of stay was greater in those with prolonged QTc, 7.2 (IQR 2.4‐13.2) days vs 3.3 (IQR 1.3‐10.0; P = 0.004), however, in a regression model, presence of QTc did not independently affect length of stay.Conclusions QTc interval prolongation is frequent among patients admitted to AMU. QT interval‐prolonging drugs are commonly prescribed to patients presenting with prolonged QTc but whether this affects clinical outcomes is uncertain.

The relationship between QT interval indices with cardiac autonomic neuropathy in diabetic patients: a case control study

“…QTc prolongation has been associated with severity of CAN in DM patients [5]. The main causes of QTc prolongation are long-term diabetes, ischemic heart disease, and autonomic system insufficiency; with less frequency, etiologies such as water and electrolyte imbalance [6]. Long QTc causes serious arrhythmias and sudden death, and, along with nephropathy, increases the mortality rate of patients [7].…”

Markedly prolonged QTc interval in end‐stage liver disease and risk of 30‐day cardiovascular event after liver transplant

“…Indeed, QTc value higher than 500 ms, a criterion for diagnosing severe long‐QT syndrome, is extremely prolonged and associated with a high risk of TdP in the general population 21 . Compared with estimates of 1.7% (12/712) for patients admitted to acute medical units 22 and 1.5% (150/10 180) among patients receiving in‐hospital cancer treatment, 10 the 7.5% prevalence of QTc > 500 ms for patients with ESLD is notably high. When compared with the estimated 0.7% (293/41 649) of all hospitalized patients in a large cohort, 23 the 7.5% prevalence in our study is 10.7 times higher.…”

QTc Interval Prolongation in Drug Resistant-Tuberculosis Patients Treated with Shorter Treatment Regimen

“…Nevertheless, these drugs have the ability to delay cardiac repolarization, represent as corrected QT (QTc) interval prolongation on electrocardiogram (ECG) (6) . QTc interval prolongation can disrupt normal cardiac rhythms and lead to fatal arrhythmias such as torsades de pointes (7) and lead to sudden cardiac death (8) . Thus, TB program recommends monitoring QTc interval to ensure patient safety and optimum patient outcome (3) .…”