Aims
To date, potential differences in outcomes for immigrants and non-immigrants with a cardiac resynchronization therapy (CRT), in a European setting, remain underutilized and unknown. Hence, we examined the efficacy of CRT measured by heart failure (HF)-related hospitalizations and all-cause mortality among immigrants and non-immigrants.

Methods and results
All immigrants and non-immigrants who underwent first-time CRT implantation in Denmark (2000–2017) were identified from nationwide registries and followed for up to 5 years. Differences in HF related hospitalizations and all-cause mortality were evaluated by Cox regression analyses. From 2000 to 2017, 369 of 10 741 (3.4%) immigrants compared with 7855 of 223 509 (3.5%) non-immigrants with a HF diagnosis underwent CRT implantation. The origins of the immigrants were Europe (61.2%), Middle East (20.1%), Asia-Pacific (11.9%), Africa (3.5%), and America (3.3%). We found similar high uptake of HF guideline-directed pharmacotherapy before and after CRT and a consistent reduction in HF-related hospitalizations the year before vs. the year after CRT (61% vs. 39% for immigrants and 57% vs. 35% for non-immigrants). No overall difference in 5-year mortality among immigrants and non-immigrants was seen after CRT [24.1% and 25.8%, respectively, P-value = 0.50, hazard ratio (HR) = 1.2, 95% confidence interval (CI): 0.8–1.7]. However, immigrants of Middle Eastern origin had a higher mortality rate (HR = 2.2, 95% CI: 1.2–4.1) compared with non-immigrants. Cardiovascular causes were responsible for the majority of deaths irrespective of immigration status (56.7% and 63.9%, respectively).

Conclusion
No overall differences in efficacy of CRT in improving outcomes between immigrants and non-immigrants were identified. Although numbers were low, a higher mortality rate among immigrants of Middle Eastern origin was identified compared with non-immigrants.