Subtypes of atrial fibrillation with concomitant valvular heart disease derived from electronic health records: phenotypes, population prevalence, trends and prognosis

Abstract

Aims: To evaluate population-based electronic health record (EHR) definitions of atrial fibrillation (AF) and valvular heart disease (VHD) subtypes, time trends in prevalence and prognosis.

Methods and results: A total of 76 019 individuals with AF were identified in England in 1998-2010 in the CALIBER resource, linking primary and secondary care EHR. An algorithm was created, implemented, and refined to identify 18 VHD subtypes using 406 diagnosis, procedure, and prescription codes. Cox models were used to investigate associations with a composite endpoint of incident stroke (ischaemic, haemorrhagic, and unspecified), systemic embolism (SSE), and all-cause mortality. Among individuals with AF, the prevalence of AF with concomitant VHD increased from 11.4% (527/4613) in 1998 to 17.6% (7014/39 868) in 2010 and also in individuals aged over 65 years. Those with mechanical valves, mitral stenosis (MS), or aortic stenosis had highest risk of clinical events compared to AF patients with no VHD, in relative [hazard ratio (95% confidence interval): 1.13 (1.02-1.24), 1.20 (1.05-1.36), and 1.27 (1.19-1.37), respectively] and absolute (excess risk: 2.04, 4.20, and 6.37 per 100 person-years, respectively) terms. Of the 95.2% of individuals with indication for warfarin (men and women with CHA2DS2-VASc ≥1 and ≥2, respectively), only 21.8% had a prescription 90 days prior to the study.

Conclusion: Prevalence of VHD among individuals with AF increased from 1998 to 2010. Atrial fibrillation associated with aortic stenosis, MS, or mechanical valves (compared to AF without VHD) was associated with an excess absolute risk of stroke, SSE, and mortality, but anticoagulation was underused in the pre-direct oral anticoagulant (DOAC) era, highlighting need for urgent clarity regarding DOACs in AF and concomitant VHD.

Keywords: Atrial fibrillation; Electronic health records; Mortality; Stroke; Systemic embolism; Valvular heart disease.

Figure 1

Electronic health record algorithm to classify AF and concomitant VHD. Flow diagram illustrates electronic health record algorithm for classifying individuals with AF and prevalent valvular disease at study index into one of 18 valvular AF subtypes. The algorithm considers first valve replacements, followed by valve repairs and then valve diseases, which are recorded at any prior time point in an individual’s medical history. The algorithm is underpinned by 406 diagnosis, procedure, and prescription codes from the Read, ICD-10, OPCS-4, and BNF systems. Full code list and electronic health record algorithm provided in Supplementary material online, Appendix. AF, atrial fibrillation; VHD, valvular heart disease.

Figure 2

Trends in prevalence of valvular heart disease among 76 019 cases of AF (1998–2010) by age groups. AF, atrial fibrillation.

Figure 3

Trends in prevalence of valvular AF subtypes (1998–2010). AF, atrial fibrillation.

Figure 4

AF and VHD subtypes and adjusted risk of incident stroke, systemic embolism, and all-cause mortality. Reference category: patients with AF and no record of valvular heart disease. Hazard ratios adjusted for age, sex, warfarin, heart failure, hypertension, diabetes mellitus, stroke, transient ischaemic attack or systemic embolism, and vascular disease. AF, atrial fibrillation; aHR (95% CI), adjusted hazard ratio (95% confidence interval); VHD, valvular heart disease; nos, not otherwise specified.

Figure 5

Subtypes of AF with concomitant valvular heart disease and risk of incident stroke, systemic embolism, and all-cause mortality. OAC, oral anticoagulation.