Association Between Dynamic Change of QT Interval and Long-Term Cardiovascular Outcomes: A Prospective Cohort Study

Background: The prolongation or shortening of heart rate-corrected QT (QTc) predisposes patients to fatal ventricular arrhythmias and sudden cardiac death (SCD), but the association of dynamic change of QTc interval with mortality in the general population remains unclear.Methods: A total of 11,798 middle-aged subjects from the prospective, population-based cohort were included in this analysis. The QTc interval corrected for heart rate was measured on two occasions around 3 years apart in the Atherosclerosis Risk in Communities (ARIC) study. The ΔQTc interval was calculated by evaluating a change in QTc interval from visit 1 to visit 2.Results: After a median follow-up of 19.5 years, the association between the dynamic change of QTc interval and endpoints of death was U-shaped. The multivariate-adjusted hazard ratios (HRs) comparing subjects above the 95th percentile of Framingham–corrected ΔQTc (ΔQTcF) (≥32 ms) with subjects in the middle quintile (0–8 ms) were 2.69 (95% CI, 1.68–4.30) for SCD, 2.51 (1.68–3.74) for coronary heart disease death, 2.10 (1.50–2.94) for cardiovascular death, and 1.30 (1.11–1.55) for death from any cause. The corresponding HRs comparing subjects with a ΔQTcF below the fifth percentile (<-23 ms) with those in the middle quintile were 1.82 (1.09–3.05) for SCD, 1.83 (1.19–2.81) for coronary heart disease death, 2.14 (1.51–2.96) for cardiovascular death, and 1.31 (1.11–1.56) for death from any cause. Less extreme deviations of ΔQTcF were also associated with an increased risk of death. Similar, albeit weaker associations also were observed with ΔQTc corrected with Bazett's formula.Conclusions: A dynamic change of QTc interval is associated with increased mortality risk in the general population, indicating that repeated measurements of the QTc interval may be available to provide additional prognostic information.

Left Atrioventricular Coupling Index as a Prognostic Marker of Cardiovascular Events: The MESA Study

Both left atrial and left ventricular functional parameters influence the prognosis of patients with cardiovascular diseases. This study aimed to investigate the prognostic value of a novel left atrioventricular coupling index (LACI) in a population without history of cardiovascular diseases at baseline. Participants of the Multi-Ethnic Study of Atherosclerosis who underwent a baseline cardiovascular magnetic resonance study were analyzed. LACI was defined by the ratio of the left atrial end-diastolic volume divided by the left ventricular end-diastolic volume. Cox proportional hazard models were used to evaluate the association between LACI and atrial fibrillation, heart failure, coronary heart disease death, and hard cardiovascular disease defined by myocardial infarction, resuscitated cardiac arrest, fatal and nonfatal stroke, or coronary heart disease death. Among the 4124 participants (61.5±10.1 years, 47.4% men), 1074 cardiovascular events were observed (mean follow-up, 13.0±3.2 years). Greater LACI was independently associated with atrial fibrillation (hazard ratio, 1.86 [95% CI, 1.69–2.04]), heart failure (hazard ratio, 1.50 [95% CI, 1.38–1.62]), hard cardiovascular disease (1.23 [95% CI, 1.13–1.34]), and coronary heart disease death (hazard ratio, 1.29 [95% CI, 1.15–1.45]; all P <0.0001). After adjustment for traditional cardiovascular risk factors, LACI showed significant improvement in model discrimination and reclassification compared with currently used standard models to predict outcomes. LACI is a strong predictor for the incidence of heart failure, atrial fibrillation, hard cardiovascular disease, and coronary heart disease death. LACI has incremental prognostic value to predict cardiovascular events over traditional risk factors and better discrimination and reclassification power compared with individual left atrial or left ventricular parameters.