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Heart failure can be defined as the heart’s inability
to pump sufficient cardiac output to meet the body’s
metabolic demand. Developing slowly, often over years, many
people with heart failure may not be aware of their condition.
People with diabetes have a five-fold increased risk of developing
heart failure when compared with people without diabetes [Kannel,
1978], and the relative risk is higher in women than in
men [Kannel and McGee,
1979]. In this subgroup of patients, two reasons have
been postulated for the increased risk:
- The extent and severity of existing occlusive coronary
artery disease
- The presence of a specific diabetic heart muscle disease
[Zuanetti, 2000].
People with diabetes have an increased risk of myocardial
infarction combined with an increased risk of immediate and
delayed mortality, due to heart failure. Coronary heart disease
progresses more rapidly in people with diabetes. Lesions are
more extensive and severe and run a more aggressive course,
which may lead to more severe heart failure [Gray
and Yudkin, 1997; Shaw, 1996; Yudkin and Hendra, 1992].
It may also be possible that conditions such as angina and
myocardial infarction go undiagnosed until heart failure is
recognised.
Although the majority of cases of heart failure in people
with diabetes are due to pre-existing cardiac conditions,
diabetes can cause a specific cardiomyopathy that over time
develops into heart failure [Gray
and Yudkin, 1997]. Diabetic cardiomyopathy is an independent
left ventricular dysfunction caused by hypertrophy of the
myocytes and interstitial fibrosis [Lavine
and Gellman, 2002]. Abnormal diastolic function can be
an early indicator of diabetic cardiomyopathy [Gray
and Yudkin, 1997] and correlates strongly with the duration
of diabetes [Zarich et
al, 1988], the extent of microvascular complications
[Airaksinen et al, 1984; Paillole et al, 1989; Zarich et al,
1988] and autonomic dysfunction [Zola
et al, 1986]. Later in the course of the disease both
left ventricular systolic and diastolic dysfunction are present
[Raev, 1994]. More severe
left ventricular dysfunction leads to heart failure [Gray
and Yudkin, 1997]. It is possible that this disease is
present in those who suffer myocardial infarction, but does
not become clinically evident until after the infarction [Gray
and Yudkin, 1997].
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