Adenosine stress CMR T1-mapping detects early microvascular dysfunction in patients with type 2 diabetes mellitus without obstructive coronary artery disease

Abstract

BackgroundType 2 diabetes mellitus (T2DM) is associated with coronary microvascular dysfunction in the absence of obstructive coronary artery disease (CAD). Cardiovascular magnetic resonance (CMR) T1-mapping at rest and during adenosine stress can assess coronary vascular reactivity. We hypothesised that the non-contrast T1 response to vasodilator stress will be altered in patients with T2DM without CAD compared to controls due to coronary microvascular dysfunction.MethodsThirty-one patients with T2DM and sixteen matched healthy controls underwent CMR (3 T) for cine, rest and adenosine stress non-contrast T1-mapping (ShMOLLI), first-pass perfusion and late gadolinium enhancement (LGE) imaging. Significant CAD (>50% coronary luminal stenosis) was excluded in all patients by coronary computed tomographic angiography.ResultsAll subjects had normal left ventricular (LV) ejection and LV mass index, with no LGE. Myocardial perfusion reserve index (MPRI) was lower in T2DM than in controls (1.60 ± 0.44 vs 2.01 ± 0.42; p = 0.008). There was no difference in rest native T1 values (p = 0.59). During adenosine stress, T1 values increased significantly in both T2DM patients (from 1196 ± 32 ms to 1244 ± 44 ms, p < 0.001) and controls (from 1194 ± 26 ms to 1273 ± 44 ms, p < 0.001). T2DM patients showed blunted relative stress non-contrast T1 response (T2DM: ΔT1 = 4.1 ± 2.9% vs. controls: ΔT1 = 6.6 ± 2.6%, p = 0.007) due to a blunted maximal T1 during adenosine stress (T2DM 1244 ± 44 ms vs. controls 1273 ± 44 ms, p = 0.045).ConclusionsPatients with well controlled T2DM, even in the absence of arterial hypertension and significant CAD, exhibit blunted maximal non-contrast T1 response during adenosine vasodilatory stress, likely reflecting coronary microvascular dysfunction. Adenosine stress and rest T1 mapping can detect subclinical abnormalities of the coronary microvasculature, without the need for gadolinium contrast agents. CMR may identify early features of the diabetic heart phenotype and subclinical cardiac risk markers in patients with T2DM, providing an opportunity for early therapeutic intervention.

Cardiac T1 mapping: Techniques and applications

“…This study suggests the potential for classification of normal vs. ischemic or infarcted myocardium using a combination of native and stress T 1 mapping without gadolinium contrast. More recent stress T 1 studies have distinguished microvascular dysfunction and epicardial obstructive CAD in native coronary arteries and identified reduced T 1 stress reactivity in patients with well‐controlled type 2 diabetes mellitus without obstructive CAD, suggestive of early microvascular changes . Other groups have also employed the technique in small samples but the ability to reliably distinguish between normal, ischemic, and infarcted myocardium remains to be definitively proven …”

The Role of High-Density Lipoproteins in Diabetes and Its Vascular Complications

“…However, there is considerable overlap between these broad classifications. The risk of developing major PAD, for instance, is strongly associated with microvascular disease, particularly macroalbuminuria and previous retinal photocoagulation [ 7 ], while advanced imaging techniques have revealed the presence of early coronary microvascular dysfunction in T2DM patients without obstructive CAD [ 8 ]. These observations suggest common pathophysiological processes underlying a range of vascular complications.…”

Variability of cardiovascular magnetic resonance (CMR) T1 mapping parameters in healthy volunteers during long-term follow-up

“… 11 Furthermore, T1 mapping might be able to detect early microvascular dysfunction in adenosine stress tests. 12 …”