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Cardio Diabetes Medicine 2017 305

Structural changes include: (i) LV hypertrophy, as- strated in one-third of patients with Type II diabetes
sessed by 2D echocardiography or cardiac magnetic independent of blood pressure or ACE inhibitor use
resonance imaging (CMR); (ii) increased integrated . Similarly Kimball et al. found increased LV mass
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backscatter in the LV (septal and posterior wall); and performance in Type I diabetic patients with mi-
and (iii) late Gd enhancement of the myocardium in croalbuminuria. Framingham showed an association
CMR. Functional changes are due to: (i) LV diastolic between diabetes mellitus and increased LV mass
dysfunction, assessed by pulsed Doppler echo cardi- independent of conventional risk factors in women,
ography and TDI; (ii) LV systolic dysfunction, demon- but not in men. A large echocardiography study of
strated by TDI/SRI; and (iii) limited systolic and/or di- American Indians with diabetes found a reduction
astolic functional reserve, assessed by exercise TDI. in LV systolic chamber size and LV function, despite
Finally metabolic changes are primarily associated increased LV mass in both sexes. It has been sug-
with: (i) a reduced ratio of cardiac phosphocreatine gested that aortic stiffness may contribute to the de-
to adenosine triphosphate; and (ii) elevated myocar- velopment of LVH and diastolic dysfunction in dia-
dial triglyceride content. Catheter-based diagnosis betic patients by increasing end-systolic wall stress.
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of diabetic cardiomyopathy is rarely employed at Erenet al. also found an association between aortic
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present, because other more sensitive and specific stiffness and diastolic dysfunction inpatients with ei-
noninvasive techniques are used instead. Coronary ther hypertension or diabetes or both. Earlier Dop-
angiography is useful for the diagnosis of coronary pler studies have been criticized for underestimating
artery disease that may coexist with and complicate the degree of diastolic dysfunction since they failed
diabetic cardiomyopathy. to account for pseudonormal filling patterns, which
have been observed in up to 60% of normotensive
DIAGNOSTIC METHODS diabetic patients. This suggests that up to 50% of
patients with diastolic dysfunction could be missed
Thus, it is clear from the discussion above that a
range of molecular changes may underlie the devel- on standard echocardiography. Pseudo normalized
opment of diabetic cardiomyopathy. Of clinical rel- filling patterns can be picked up by asking patients
evance is the means by which clinicians diagnose to perform the Valsalva manoeuvre whilst assessing
and characterize this problem, perhaps prior to it trans-mitral and pulmonary Doppler signals. There-
becoming clinically manifest. This is important as it fore echocardiography is a useful non invasive tool
may allow intervention at a point where significant to assess for the presence of LVH and systolic and
cardiac dysfunction has not yet ensued. diastolic dysfunction and can provide prognostic in-
formation in diabetic patients suspected of having
cardiomyopathy.
Echocardiography
Clinically apparent diabetic cardiomyopathy may Tissue Doppler echocardiography
take several years to develop, but echocardiography
can detect significant abnormalities well before the In standard Echocardiography, a high-veloci-
onset of symptomatic HF. There are different types ty low-amplitude filter looks solely at blood flow
of echocardiography which are used in diagnosing through the heart to define valvular function. Newer
LV dysfunction. technologies such as TDI (tissue Doppler echocar-
diographic imaging) look promising as they apply a
Conventional echocardiography high-velocity low-amplitude filter to the myocardium
enabling an assessment of myocardial tissue veloc-
Early abnormalities are defined by a preserved LV ities. The advantage over standard Doppler echo-
ejection fraction with reduced early diastolic filling, cardiography is that the results are independent
prolongation of isovolumetric relaxation and in- of changes in pre-load. This provides a particularly
creased atrial filling, the presence of which confirms useful tool for defining subtle systolic and diastolic
diastolic dysfunction. A reduction in LV distensibility dysfunction. In a recent study, although there was a
is characterized by an increased PEP (pre-ejection significant reduction in resting Sm (peak myocardial
period) and shorter LVET (LV ejection time), resulting systolic velocity) and Em (early diastolic velocity) in
in an increased PEP/LVET ratio.Such abnormalities diabetic patients,the response to dobutamine stress
have been demonstrated in a group of normotensive did not differ from control subjects, suggesting that
diabetic patients without overt microvascular or mac- ischaemia due to small vessel disease may not be
rovascular complications. important in early diabetic heart muscle disease. TDI
Galderisi et al. found a 22% increase in LV mass also quantifies both longitudinal and circumferential
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in diabetic women and, recently, LVH was demon- cardiac contraction. Longitudinal (long-axis) contrac-

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