Increased risk of AF in women with T1D
Women with type 1 diabetes (T1D), particularly those with poor glycaemic control and renal function, may have an elevated risk of atrial fibrillation (AF), according to findings from a Swedish study.
After adjusting for age, baseline comorbidities, duration of diabetes, education level, and place of birth, women with T1D had a 50 percent higher risk of AF compared with their nondiabetic counterparts (hazard ratio [HR], 1.50; p<0.0001). Men with T1D also had an elevated AF risk but it was less pronounced than that among women (HR, 1.13; p=0.029). [Lancet Diabetes Endocrinol 2017;doi:10.1016/S2213-8587(17)30262-0]
The risk of AF in T1D was especially evident in women aged 50–64 years (HR, 1.60; p<0.0001) and ≥65 years (HR, 1.34; p=0.0019) and among men aged 35–49 years (HR, 1.42; p=0.0075) with no apparent increased risk in other age groups.
Individuals with T1D and poor glycaemic control (HbA1c levels ≥9.7 percent) had a further increased risk of AF (HR, 2.20 and 2.62; p<0.0001 for men and women, respectively).
Compared with nondiabetics, AF risk was elevated in women with T1D and normoalbuminuria (HR, 1.32; p=0.0023) and microalbuminuria (HR, 1.58; p=0.0028) and not in men with either condition.
The link between poor glycaemic control and elevated AF risk was present in individuals with normoalbuminuria (HR, 1.98; p=0.0008 in women with HbA1c 8.8–9.6 percent and HR, 1.89; p=0.046 in men with HbA1c ≥9.7 percent), with no increased AF risk in men and women with HbA1c <9.7 and <8.8 percent, respectively.
Women with eGFR of ≥60 mL/min/1.73 m2 also had an elevated risk of AF if their HbA1c levels were 7.9–8.7 percent (HR, 1.36; p=0.048) and 8.8–9.6 percent (HR, 1.78; p=0.0056), while eGFR of ≥60 mL/min/1.73 m2 had no bearing on AF risk in men regardless of HbA1c level.
“Our findings suggest that the excess risk of AF in men is most likely to occur in the setting of advanced renal complications,” said the researchers. “[A]lthough the excess risk of AF was greater in women, the absolute risk of AF was somewhat greater in men, indicating sex alone is not the only variable to screen in the clinical setting.”
“The finding that severe renal complications are a risk factor for AF could be accounted for partly by renal complications leading to hypertension … renal complications are [also] associated with heart failure, contributing to AF,” they said.
In this prospective case-control study, researchers obtained data of individuals with T1D from the Swedish National Diabetes Registry (n=36,258, mean age 35.6 years, 45 percent female) and matched each of them with five age-, sex-, and county of residence-controls from the Swedish Population Register (n=179,980, mean age 35.4 years, 45 percent female).
Participants were followed-up for a median 9.7 and 10.2 years for patients with T1D and controls, respectively, during which 749 patients with T1D and 2,882 controls were diagnosed with AF based on data obtained from the Swedish National Patient Registry.
According to the researchers, individuals with T1D would probably have more outpatient visits than their nondiabetic counterparts, thus increasing the likelihood of AF detection in this group of patients.
“Since both T1D and AF are risk factors for stroke, clarification of disease interaction is important to provide proper risk assessment and appropriate treatment,” said the researchers.
“[G]lycaemic control should be optimized to reduce excess risk of AF … in the clinical setting, screening for AF can be done by ECG, or AF could be suspected based on a finding of an irregular heartbeat,” they said.
“Our study findings highlight the importance of keeping HbA1c values within recommended ranges and controlling renal complications,” they said, recommending that future research look into confirming the risk factors and identifying “specific screening groups for AF”.