Ethnic differences in the association of QRS duration with ejection fraction and outcome in heart failure

Background QRS duration (QRSd) criteria for device therapy in heart failure (HF) were derived from predominantly white populations and ethnic differences are poorly understood. Methods We compared the association of QRSd with ejection fraction (EF) and outcomes between 839 Singaporean Asian and 11221 Swedish white patients with HF having preserved EF (HFPEF)and HF having reduced EF (HFREF) were followed in prospective population-based HF studies. Results Compared with whites, Asian patients with HF were younger (62 vs 74years, pamp;lt;0.001), had smaller body size (height 163 vs 171cm, weight 70 vs 80kg, both pamp;lt;0.001) and had more severely impaired EF (EF was amp;lt;30% in 47% of Asians vs 28% of whites). Overall, unadjusted QRSd was shorter in Asians than whites (101 vs 104ms, pamp;lt;0.001). Lower EF was associated with longer QRSd (pamp;lt;0.001), with a steeper association among Asians than whites (p(interaction)amp;lt;0.001), independent of age, sex and clinical covariates (including body size). Excluding patients with left bundle branch block (LBBB) and adjusting for clinical covariates, QRSd was similar in Asians and whites with HFPEF, but longer in Asians compared with whites with HFREF (p=0.001). Longer QRSd was associated with increased risk of HF hospitalisation or death (absolute 2-year event rate for 120ms was 40% and for amp;gt;120ms it was 52%; HR for 10ms increase of QRSd was 1.04 (1.03 to 1.06), pamp;lt;0.001), with no interaction by ethnicity. Conclusion We found ethnic differences in the association between EF and QRSd among patients with HF. QRS prolongation was similarly associated with increased risk, but the implications for ethnicity-specific QRSd cut-offs in clinical decision-making require further study