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Gowdar et al. Diabetes mellitus and takotsubo cardiomyopathy

Diabetes mellitus with autonomic neuropathy

Autonomic dysfunction
of local cardiac
sympathetic nerves Splanchnic autonomic
Systemic secretion
of adrenaline dysfunction
Capsule
Inhibition of local cardiac Cortex
norepinephrine release Medulla

Reduced sympathetic surge and
myocardial stunning

Inhibit development of takotsubo cardiomyopathy

Figure 1: Pathophysiologic mechanism of protective effect of diabetes mellitus on development of takotsubo cardiomyopathy

measurements of hemodynamics in response to to higher prevalence rates of DM in ACS patients. DM
acetylcholine and adenosine were used for evaluation. may confer a protective effect on the evolution of TC.
Microvascular dysfunction was noted to be present An increasingly plausible explanation is that autonomic
in a large proportion of patients (64%). Evaluation neuropathy from DM leads to cardiac sympathetic
of underlying cardiac risk factors showed that autonomic dysfunction and splanchnic autonomic
hyperlipidemia and hypertension were common, with dysfunction resulting in reduced local norepinephrine
hyperlipidemia seen in up to 61% and hypertension release and reduced systemic epinephrine release from
in up to 46% of patients. A noteworthy finding was chromaffin cells in the adrenal medulla, respectively.
that DM was quite uncommon in all patient groups, This autonomic neuropathy and catecholamine
with the prevalence of DM only ranging from 7% hyposecretion may lead to significant blunting and
to 12%. Since microvascular dysfunction has been amelioration of cardiomyocyte injury and myocardial
increasingly thought to be one of the pivotal factors stunning, resulting from the catecholamine storm/surge
in the pathogenesis of TC, it somewhat supports an thought to occur in the pathogenesis of TC. Further
interesting association since diabetics also have a retrospective and prospective studies on TC should
lower incidence of TC. [31] On the contrary, some studies ensure accurate reporting of the underlying prevalence
have also suggested increasing prevalence of coronary of comorbid conditions, including characterizing the
microvascular dysfunction in diabetics. [31,34,35] Given particulars of diabetes mellitus in this population, to
that microvascular dysfunction is also an important further define the postulated protective role of diabetes
pathogenic factor in TC, this discordance currently in these patients.
has no clear explanation and needs further evaluation.
Future studies will strengthen our understanding on LIMITATIONS AND FUTURE DIRECTIONS
this subject.
The data currently available on the subject is quite
CONCLUSION limited. The prevalence of DM in most of the studies
remains relatively low. Dedicated studies on TC are
Knowledge about the pathogenesis and risk factors needed incorporating patients with DM to explore the
associated with TC is significantly accelerating. Multiple relationship further between DM and TC. Since the
studies have reported low prevalence and rates of DM in studies currently available are mainly retrospective
patients with TC. This is lower than the prevalence rates and case-control studies, further prospective studies
of diabetes in the general population, and in contrast are needed to strengthen our understanding of
134 Vessel Plus ¦ Volume 1 ¦ September 26, 2017