Palla AR et al. Clin Cardiol. In press.
To the Editor:
Palla et al have recently reported that pretreatment with low-dose β-adrenergic antagonist therapy does not affect the severity of takotsubo cardiomyopathy.1 Their study result provides new insights into the prevention of takotsubo cardiomyopathy because β-adrenoceptor blocker has been considered to prevent or at least attenuate the intensity of the detrimental cardiac effects in this syndrome. Takotsubo cardiomyopathy has been regarded in states of catecholamine excess due to stress. One study reported more than 2 times higher norepinephrine levels in patients with takotsubo cardiomyopathy than those with myocardial infarction. However, elevated catecholamine levels are not uniformly found in patients with this syndrome. Our previous study demonstrated that only half of the study patients had elevated catecholamine levels,2 and another study also reported no elevated catecholamine levels even in the acute phase. Sharkey et al conducted a study on 136 patients with takotsubo cardiomyopathy.3 Of these, 25 patients had this syndrome while β-blockers were administered. They thus concluded that β-blockers administered in traditional dosage did not absolutely prevent either the first or recurrent episodes of takotsubo cardiomyopathy. In rat models, we have reported that blocking of both α- and β-adrenoceptors eliminates the upregulation of immediate early genes induced by stress.2 A recent study has investigated cardiac and vascular gene profiles in response to immobilization stress in rats, and reported that altered expression of cardiac genes is blunted by the pretreatment with β-1 adrenoceptor blocker or α-1 + β-1 adrenoceptor blockers.4
We previously suggested that combined α- and β-blockers would be rational for the prevention of this syndrome.2 Accordingly, further investigation in patients administered with β-1 adrenoreceptor blocker and those administered with both α- and β-adrenoreceptor blockers will provide different aspects and more valuable knowledge of takotsubo cardiomyopathy. The study result presented by Palla et al is thus considered appropriate for more detailed investigation of possible takotsubo cardiomyopathy prevention.