The cardiovascular changes underlying a low cardiac output with exercise in patients with type 2 diabetes mellitus.

The significant morbidity and premature mortality of type 2 diabetes mellitus (T2DM) is largely associated with its cardiovascular consequences. Focus has long been on the arterial atheromatosis of DM giving rise to early stroke and myocardial infarctions, whereas less attention has been given to its non-ischemic cardiovascular consequences. Irrespective of ischemic changes, T2DM is associated with heart failure (HF) most commonly with preserved ejection fraction (HFpEF). Largely due to increasing population ages, hypertension, obesity and T2DM, HFpEF is becoming the most prevalent form of heart failure. Unfortunately, randomized controlled trials of HFpEF have largely been futile, and it now seems logical to address the important different phenotypes of HFpEF to understand their underlying pathophysiology. In the early phases, HFpEF is associated with a significantly impaired ability to increase cardiac output with exercise. The lowered cardiac output with exercise results from both cardiac and peripheral causes. T2DM is associated with left ventricular (LV) diastolic dysfunction based on LV hypertrophy with myocardial disperse fibrosis and significantly impaired ability for myocardial blood flow increments with exercise. T2DM is also associated with impaired ability for skeletal muscle vasodilation during exercise, and as is the case in the myocardium, such changes may be related to vascular rarefaction. The present review discusses the underlying phenotypical changes of the heart and peripheral vascular system and their importance for an adequate increase in cardiac output. Since many of the described cardiovascular changes with T2DM must be considered difficult to change if fully developed, it is suggested that patients with T2DM are early evaluated with respect to their cardiovascular compromise.

Myocardial Blood Flow Determination From Contrast-Free Magnetic Resonance Imaging Quantification of Coronary Sinus Flow.

BACKGROUND: Determination of myocardial blood flow (MBF) with MRI is usually performed with dynamic contrast enhanced imaging (MBFDCE ). MBF can also be determined from coronary sinus blood flow (MBFCS ), which has the advantage of being a noncontrast technique. However, comparative studies of MBFDCE and MBFCS in large cohorts are lacking. PURPOSE: To compare MBFCS and MBFDCE in a large cohort. STUDY TYPE: Prospective, sequence-comparison study. POPULATION: 147 patients with type 2 diabetes mellitus (age: 56+/-12 years; 106 male; diabetes duration: 12.9+/-8.1 years), and 25 age-matched controls. FIELD STRENGTH/SEQUENCES: 1.5 Tesla scanner. Saturation recovery sequence for MBFDCE vs. phase-contrast gradient-echo pulse sequence (free-breathing) for MBFCS . ASSESSMENT: MBFDCE and MBFCS were determined at rest and during coronary dilatation achieved by administration of adenosine at 140 µg/kg/min. Myocardial perfusion reserve (MPR) was calculated as the stress/rest ratio of MBF values. Coronary sinus flow was determined twice in the same imaging session for repeatability assessment. STATISTICAL TESTS: Agreement between MBFDCE and MBFCS was assessed with Bland and Altman's technique. Repeatability was determined from single-rater random intraclass and repeatability coefficients. RESULTS: Rest and stress flows, including both MBFDCE and MBFCS values, ranged from 33 to 146 mL/min/100 g and 92 to 501 mL/min/100 g, respectively. Intraclass and repeatability coefficients for MBFCS were 0.95 (CI 0.90; 0.95) and 5 mL/min/100 g. In Bland-Altman analysis, mean bias at rest was -1.1 mL/min/100 g (CI -3.1; 0.9) with limits of agreement of -27 and 24.8 mL/min/100 g. Mean bias at stress was 6.3 mL/min/100 g (CI -1.1; 14.1) with limits of agreement of -86.9 and 99.9. Mean bias of MPR was 0.11 (CI: -0.02; 0.23) with limits of agreement of -1.43 and 1.64. CONCLUSION: MBF may be determined from coronary sinus blood flow, with acceptable bias, but relatively large limits of agreement, against the reference of MBFDCE . LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 2.

Myocardial Extracellular Volume Expansion in Type 2 Diabetes Is Associated With Ischemic Heart Disease, Autonomic Neuropathy, and Active Smoking.

OBJECTIVE: Myocardial interstitial fibrosis expands the extracellular volume (ECV) and in patients with type 2 diabetes is implicated in development of heart failure. ECV can be determined with gadolinium contrast MRI. We investigated which known risk factors for cardiovascular disease were associated with increased ECV in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: A total of 296 patients with type 2 diabetes and 25 sex and age-matched control subjects were included in a cross-sectional MRI study. The influence of risk factors on ECV was investigated with multiple regression analysis. RESULTS: Control subjects and patients with type 2 diabetes without complications had similar ECV (mean ± SD 27.4 ± 2.1% vs. 27.9 ± 2.6%, P = 0.4). Compared with patients without, ECV was significantly increased in patients with one or more complications (29.0 ± 3.3%, P = 0.02). Both in univariable analysis and after multivariable adjustment, ischemic heart disease, autonomic neuropathy, and active smoking were associated with increased levels of ECV. Active smoking exhibited the largest effect size (ß = 2.0 percentage points, 95% CI 0.7-3.3). Former smokers ECV similar to that of never smokers. Albuminuria and systolic blood pressure were inversely associated with ECV in multivariable analysis, but after adjustment for medication suspected to affect ECV, the association with albuminuria was no longer significant (P = 0.1). Sodium-glucose cotransporter 2 inhibitor treatment was not significantly associated with reduced ECV (-0.8%, 95% CI -1.7 to 0.06, P = 0.067). CONCLUSIONS: Patients with complications of diabetes have increased ECV, not seen in patients without complications. Ischemic heart disease, autonomic neuropathy, and active but not former smoking were highly associated with increased ECV.

Metabolic improvement with short-term, glucagon-like peptide-1 receptor agonist treatment does not improve cardiac diastolic dysfunction in patients with type 2 diabetes: A randomized, double-blind, placebo-controlled trial.

AIM: To investigate if short-term treatment with liraglutide, a glucagon-like peptide-1 receptor agonist, improves left ventricular diastolic function. MATERIALS AND METHODS: An investigator-initiated, double-blind, randomized, placebo-controlled trial on the effect of 18 weeks of treatment with liraglutide on diastolic function was assessed in patients with type 2 diabetes with signs of diastolic dysfunction (echo-Doppler determined E/e' ≥ 9 and/or lateral e' ≤ 10 cm/s). Primary outcomes were improved left ventricle filling (the early peak filling rate [ePFR]) and left atrium ease of emptying (the passive emptying fraction [LAPEF ]), assessed by cardiac magnetic resonance imaging at rest and during chronotropic stress. Secondary outcomes included left ventricular and left atrial volumes and systolic function, measures of aortic stiffness and echocardiographic diastolic variables. RESULTS: Forty patients were randomized to liraglutide subcutaneously 1.8 mg/day (n = 20) or placebo (n = 20). Liraglutide reduced HbA1c (-0.47%, 95% CI [-0.88% to -0.06%] [-5.1, 95% CI {-9.7 to -0.62} mmol/mol]) and weight (-2.9, 95% CI [-4.6 to -1.2] kg); both P < .03. Liraglutide did not change ePFR at rest (-24 ± 60 vs. -6 ± 46 mL/s), during stress (2 ± 58 vs. -2 ± 38 mL/s), or the changes from rest to stress (12.9 ± 72.5 vs. 4.7 ± 104.0; all P > .05). LAPEF decreased with liraglutide during stress (-3.1% [-9.0%, 1.1%] vs. 1.0% [-2.9%, 6.1%]; P = .049), but no changes were evident at rest (-4.3% [-7.9%, 1.9%] vs. -0.6% [-3.1%, 2.2%]; P = .19), or for the changes from rest to stress (-1.7 ± 8.4 vs. 0.8 ± 8.2; P = .4). Secondary outcomes were unchanged by liraglutide. CONCLUSIONS: Short-term treatment with liraglutide did not improve left ventricular diastolic function, suggesting the cardioprotective effect is not exerted through the improvement in diastolic dysfunction.

Distinct non-ischemic myocardial late gadolinium enhancement lesions in patients with type 2 diabetes.

BACKGROUND: Cardiovascular magnetic resonance imaging (CMR) have described localised non-ischemic late gadolinium enhancement (LGE) lesions of prognostic importance in various non-ischemic cardiomyopathies. Ischemic LGE lesions are prevalent in diabetes (DM), but non-ischemic LGE lesions have not previously been described or systematically studied in DM. METHODS: 296 patients with type 2 DM (T2DM) and 25 sex-matched control subjects underwent echocardiography and CMR including adenosine-stress perfusion, T1-mapping and LGE. RESULTS: 264 patients and all control subjects completed the CMR protocol. 78.4% of patients with T2DM had no LGE lesions; 11.0% had ischemic LGE lesions only; 9.5% had non-ischemic LGE lesions only; and 1.1% had both one ischemic and one non-ischemic lesion. The non-ischemic LGE lesions were situated mid-myocardial in the basal lateral or the basal inferolateral part of the left ventricle and the affected segments showed normal to high wall thickness and normal contraction. Patients with non-ischemic LGE lesions in comparison with patients without LGE lesions had increased myocardial mass (150 ± 34 vs. 133 ± 33 g, P = 0.02), average E/e'(9.9 IQR8.7-12.6 vs. 8.8 IQR7.4-10.7, P = 0.04), left atrial maximal volume (102 IQR84.6-115.2 vs. 91 IQR75.2-100.0 mL, P = 0.049), NT-proBNP (8.9 IQR5.9-19.7 vs. 5.9 IQR5.9-10.1 µmol/L, P = 0.02) and high-sensitive troponin (15.6 IQR13.0-26.1 vs. 13.0 IQR13.0-14.6 ng/L, P = 0.007) and a higher prevalence of retinopathy (48 vs. 25%, P = 0.009) and autonomic neuropathy (52 vs. 30.5%, P = 0.005). CONCLUSION: A specific LGE pattern with lesions in the basal lateral or the basal inferolateral part of the left ventricle was found in patients with type 2 diabetes. Trial registration https://www.clinicaltrials.gov . Unique identifier: NCT02684331.

Cardiac perfusion, structure, and function in type 2 diabetes mellitus with and without diabetic complications.

AIMS: Coronary microvascular disease (CMD) is a known complication in type 2 diabetes mellitus (T2DM). We examined the relationship between diabetic complications, left ventricular (LV) function and structure and myocardial perfusion reserve (MPR) as indicators of CMD in patients with T2DM and control subjects. METHODS AND RESULTS: This was a cross-sectional study of 193 patients with T2DM and 25 controls subjects. Patients were grouped as uncomplicated diabetes (n = 71) and diabetes with complications (albuminuria, retinopathy, and autonomic neuropathy). LV structure, function, adenosine stress, and rest myocardial perfusion were evaluated by cardiovascular magnetic resonance. Echocardiography was used to evaluate diastolic function. Patients with uncomplicated T2DM did not have significantly different LV mass and E/e* but decreased MPR (3.8 ± 1.0 vs. 5.1 ± 1.5, P < 0.05) compared with controls. T2DM patients with albuminuria and retinopathy had decreased MPR (albuminuria: 2.4 ± 0.9 and retinopathy 2.6 ± 0.7 vs. 3.8 ± 1.0, P < 0.05 for both) compared with uncomplicated T2DM patients, along with significantly higher LV mass (149 ± 39 and 147 ± 40 vs. 126 ± 33 g, P < 0.05) and E/e* (8.3 ± 2.8 and 8.1 ± 2.2 vs. 7.0 ± 2.5, P < 0.05). When entered in a multiple regression model, reduced MPR was associated with increasing E/e* and albuminuria and retinopathy were associated with reduced MPR. CONCLUSIONS: Patients with uncomplicated T2DM have reduced MPR compared with control subjects, despite equivalent LV mass and E/e*. T2DM patients with albuminuria or retinopathy have reduced MPR and increased LV mass and E/e* compared with patients with uncomplicated T2DM. E/e* and MPR are significantly associated after adjustment for age, hypertension, and LV mass, suggesting a link between CMD and cardiac diastolic function. CLINICAL TRIAL REGISTRATION: https://www.clinicaltrials.org. Unique identifier: NCT02684331.