Female sex and systolic blood pressure are independently associated with coronary microvascular dysfunction in asymptomatic adults with type 2 diabetes

Introduction

Coronary microvascular dysfunction is frequently reported in people with type 2 diabetes (T2D), is associated with reduced exercise capacity, and is a prognostic marker. Identifying modifiable risk factors associated with microvascular dysfunction may facilitate early intervention to improve outcomes in these patients.

Purpose

To identify independent determinants of myocardial perfusion reserve (MPR) in asymptomatic adults with T2D and no prevalent cardiovascular disease.

Methods

Prospective cross-sectional study. People with and without T2D and no signs, symptoms or evidence of cardiovascular disease underwent comprehensive phenotyping with echocardiography, coronary artery calcium scoring, and multiparametric cardiac MRI including adenosine stress and rest perfusion with automated pixel-wise myocardial blood flow (MBF) mapping. Participants with regional perfusion defects indicating obstructive coronary disease or silent myocardial infarct on late-gadolinium enhancement were excluded from analysis. Univariable and multivariable linear regression was performed to identify independent determinants of MPR.

Results

Two-hundred people with T2D (diabetes duration 11±8 years) were compared with 39 sex- and ethnicity-matched non-diabetic controls (Table 1). People with T2D had higher body mass index (BMI) and ambulatory 24-hour systolic blood pressure (SBP). There was evidence of concentric left ventricular (LV) remodelling (higher LV mass/volume), extracellular matrix expansion (higher ECV fraction), and both systolic and diastolic dysfunction (lower global longitudinal systolic strain and E/A ratio, respectively) in those with T2D. Resting MBF was similar between groups, but stress MBF tended to be lower in T2D compared to controls with significantly reduced MPR in T2Ds (2.87±0.86 vs 3.18±0.82, p=0.043). In univariable analysis, MPR correlated with sex, 24-hour SBP, and E/e' ratio. In a multivariable model adjusting for clinical (age, sex, smoking status, BMI, ambulatory SBP, diabetes duration, HbA1c, low-density lipoprotein, albuminuria) and imaging variables (E/e' ratio, LV mass/volume, global longitudinal strain, myocardial ECV, coronary calcium score) known to affect coronary perfusion, female sex (β=−0.227, p=0.013) and 24-hour SBP (β=−0.275, p=0.001) were the only variables independently associated with MPR.

Conclusion

Female sex is associated with coronary microvascular dysfunction in asymptomatic people with T2D but not LV mass or myocardial extracellular volume. Systolic BP is the only modifiable independent determinant of MPR and may be an early target for intervention to prevent heart failure development in these patients.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): National Institute for Health Research (NIHR) United Kingdom through a Research Professorship award (RP-2017-08-ST2-007).British Heart Foundation through a Clinical Research Training Fellowship award (FS/16/47/32190).

Association of hepatic steatosis with subclinical cardiac dysfunction in asymptomatic people with type 2 diabetes

Introduction

Non-alcoholic fatty liver disease is highly prevalent among people with type 2 diabetes (T2D) and is an emerging risk factor for heart failure with preserved ejection fraction (HFpEF). Whether excess liver adiposity is simply a marker of the coexisting adverse cardiometabolic risk profile or independently contributes to the development of HFpEF is unclear.

Purpose

To assess the association between liver fat fraction and subclinical cardiac dysfunction in adults with T2D.

Methods

Prospective cross-sectional study. Two-hundred and thirty-eight adults with T2D (mean age 63±7 years, 62% males, HbA1c 7.2±1.5%, diabetes duration 10±8 years) with no signs, symptoms, or evidence of cardiovascular disease and 40 age-, sex-, and ethnicity-matched non-diabetic controls (mean age 61±8 years, 63% males, HbA1c 5.2±1.2%) underwent comprehensive phenotyping with echocardiography and multiparametric cardiac MRI including adenosine stress and rest perfusion. Volumetric liver fat fraction (VLFF) was measured using a histologically validated, proprietary MRI technique blinded to all participant details. Inter-study reproducibility was assessed in participants (n=28) who underwent a repeat MRI within two weeks. Linear regression analysis was performed to assess any independent associations between VLFF and identified markers of subclinical cardiac dysfunction in subjects with T2D.

Results

People with T2D had evidence of concentric left ventricular (LV) remodelling (higher LV mass/volume), extracellular matrix expansion (higher ECV fraction), both systolic and diastolic dysfunction (lower global longitudinal systolic strain and E/A ratio, respectively), and coronary microvascular dysfunction (lower myocardial perfusion reserve) (Table 1). VLFF demonstrated excellent inter-study reproducibility with an intra-class correlation coefficient (ICC) of 0.988 (0.974–0.994). T2Ds had higher VLFF compared to controls [7.5 (3.8–13.7)% vs 2.9 (1.7–4.7)%, p<0.001]. In multivariable regression analysis adjusting for age, sex, ethnicity, body mass index, ambulatory systolic blood pressure, HbA1c, and low-density lipoprotein, VLFF (β=−0.161, p=0.027) was independently associated with E/A, but not other imaging measures of subclinical cardiac dysfunction.

Conclusion

Liver fat fraction is elevated in people with T2D and is independently associated with early LV diastolic dysfunction. These results add to the growing evidence that ectopic fat plays an important role in the pathogenesis of HFpEF and may be a potential target for intervention.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): National Institute for Health Research (NIHR) United Kingdom through a Research Professorship award (RP-2017-08-ST2-007).British Heart Foundation through a Clinical Research Training Fellowship (FS/16/47/32190).

Unmasking early diastolic dysfunction in type 2 diabetes using the peak early-to-late diastolic strain rate ratio by cardiac MRI feature tracking

Introduction

Type 2 diabetes (T2D) is associated with early alterations in left ventricular (LV) diastolic function, which precedes the development of heart failure. These may be quantified by cardiac MRI feature tracking, which permits a direct assessment of myocardial relaxation through calculation of diastolic strain rates. Previous studies have not fully exploited this technique by integrating early and late LV diastolic relaxation in asymptomatic adults with T2D.

Purpose

To explore whether the peak early-to-late diastolic strain rate ratio (PEDSR:PLDSR), derived from cardiac MRI feature tracking, could: 1) identify diastolic dysfunction in an asymptomatic cohort of adults with T2D, 2) compare this technique with conventional echocardiographic measures of diastolic function.

Methods

Prospective cross-sectional study. People with T2D (n=253, mean age 63±7 years, 62% male, diabetes duration 11±8 years) without signs, symptoms or history of cardiovascular disease and non-diabetic controls (n=40, mean age 61±8 years, 63% male) underwent comprehensive phenotyping including echocardiography and cardiac MRI. The LV PEDSR:PLDSR was derived from cardiac MRI balanced steady-state free precession cine images using feature tracking. Correlations between circumferential PEDSR:PLDSR and echocardiography-derived E:A and E/e' were explored.

Results

Compared to controls, people with T2D had evidence of concentric LV remodelling, diastolic dysfunction, and diffuse myocardial fibrosis as demonstrated by increased LV mass/volume, E/e' ratio, and extracellular volume fraction, respectively (Table 1). People with T2D had lower PEDSR (0.87±0.23 vs 0.95±0.24 s–1, p=0.043), higher PLDSR (0.80±0.22 vs 0.67±0.16 s–1, p<0.001), and lower PEDSR:PLDSR ratio (1.18±0.46 vs 1.53±0.61, p<0.001). PEDSR:PLDSR was moderately correlated with E:A (r=0.495, p<0.001) (Figure 1) but not E/e' (r=0.087, p=0.182).

Conclusions

Compared to people without diabetes, lower PEDSR:PLDSR in asymptomatic subjects with T2D highlights impaired myocardial relaxation in early diastole and greater dependence on atrial contraction for LV filling in this group. This novel MRI measure may be promising tool to assess global diastolic function in people undergoing cardiac MRI and especially useful in those with poor echocardiographic windows. The functional and prognostic significance of PEDSR:PLDSR warrants further assessment in longitudinal studies.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): National Institute for Health Research (NIHR) United Kingdom through a Research Professorship award (RP-2017-08-ST2-007).British Heart Foundation through a Clinical Research Training Fellowship (FS/16/47/32190).