Thyroid dysfunction and incident heart failure phenotypes among older adults: the atherosclerosis risk in communities (aric) study

Background/Introduction

Abnormal thyroid hormone concentrations have been associated with adverse cardiovascular outcomes, but the relationship between thyroid dysfunction and specific heart failure phenotypes is less clear.

Purpose

To examine the association of thyroid dysfunction with the risk of incident HF in older adults without pre-existing HF.

Methods

We analyzed participants enrolled in the Atherosclerosis Risk in Communities (ARIC) study who attended the visit 5 examination (2011–2013). Participants with previous HF history, and participants treated with amiodarone, levothyroxine, and antithyroid medication were excluded. We used Cox regression models to assess the associations between serum thyroid indices (free thyroxine [FT4], total triiodothyronine [TT3], or thyroid stimulating hormone [TSH]) and incident adjudicated HF with reduced (HFrEF) and preserved (HFpEF) left ventricular ejection fraction. Continuous associations between TT3 and outcome were further assessed via Cox model using restricted cubic spline.

Results

Among 3349 participants (mean age 75±5 years, 56% women, 20% black), subclinical hypothyroidism was prevalent in 12% of participants and low T3 syndrome in 3%. Those with overt hypothyroidism (<1%) or hyperthyroidism (<1%) were not included in the analysis given the low prevalence. Over a median follow-up of 5.5 years, incident HF occurred in 198 subjects (5.9%) at a rate of 11.1 per 1000 person-years. Of these, 86 were HFrEF, 83 HFpEF, and 29 were unclassified HF. We observed an inverse association of TT3 level with risk of incident HFpEF, but not overall incident HF or incident HFrEF, after adjustment for clinical confounders and baseline NT-proBNP levels (HR per 1 SD 0.70, 95% CI 0.54–0.92; P 0.010) (Figure). Similar results were observed for the composite endpoint of incident HFpEF or all-cause death. No statistically significant associations were found between TSH or T4 levels and incident HF. Low T3 syndrome was associated with incident HFpEF, but not overall incident HF or incident HFrEF, after adjustment for clinical confounders (HR 2.71, 95% CI 1.08–6.82; P 0.035); however, its association was significantly attenuated after adjustment with NT-proBNP (HR 2.25, 95% CI 0.87–5.79; P 0.09). No statistically significant association was found between subclinical hypothyroidism and incident HF.

Conclusions

In a contemporary biracial cohort of older adults, serum T3 level was inversely associated with incident HFpEF hospitalization. T3 administration could be considered as a potential target in future clinical trials preventing HFpEF hospitalization.

Figure 1

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): The Atherosclerosis Risk in Communities Study is performed as a collaborative study supported by National Heart, Lung, and Blood Institute contracts

HbA 1c as a risk factor for heart failure in persons with diabetes: the Atherosclerosis Risk in Communities (ARIC) study

AIMS/HYPOTHESIS

Heart failure (HF) incidence in diabetes in both the presence and absence of CHD is rising. Prospective population-based studies can help describe the relationship between HbA(1c), a measure of glycaemia control, and HF risk.

METHODS

We studied the incidence of HF hospitalisation or death among 1,827 participants in the Atherosclerosis Risk in Communities (ARIC) study with diabetes and no evidence of HF at baseline. Cox proportional hazard models included age, sex, race, education, health insurance status, alcohol consumption, BMI and WHR, and major CHD risk factors (BP level and medications, LDL- and HDL-cholesterol levels, and smoking).

RESULTS

In this population of persons with diabetes, crude HF incidence rates per 1,000 person-years were lower in the absence of CHD (incidence rate 15.5 for CHD-negative vs 56.4 for CHD-positive, p<0.001). The adjusted HR of HF for each 1% higher HbA(1c) was 1.17 (95% CI 1.11-1.25) for the non-CHD group and 1.20 (95% CI 1.04-1.40) for the CHD group. When the analysis was limited to HF cases which occurred in the absence of prevalent or incident CHD (during follow-up) the adjusted HR remained 1.20 (95% CI 1.11-1.29).

CONCLUSIONS/INTERPRETATIONS

These data suggest HbA(1c) is an independent risk factor for incident HF in persons with diabetes with and without CHD. Long-term clinical trials of tight glycaemic control should quantify the impact of different treatment regimens on HF risk reduction.