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SUMMER PREFERENCE IN THE OCCURRENCE OF TAKOTSUBO CARDIOMYOPATHY IS INDEPENDENT OF AGE

2009; Wiley; Volume: 57; Issue: 8 Linguagem: Inglês

10.1111/j.1532-5415.2009.02378.x

1532-5415

Roberto Manfredini, Rodolfo Citro, Mario Previtali, Corinna Armentano, Marco Mariano Patella, Olga Vriz, Gennaro Provenza, Raffaella Salmi, Massimo Gallerani, Costantino Astarita, G. De Gregorio, Eduardo Bossone,

Cardiac Imaging and Diagnostics

To the Editor: Takotsubo cardiomyopathy (TTC) (from the Japanese words tako and tsubo, indicating an octopus trap), also called "stress cardiomyopathy" or "transient left ventricular apical ballooning syndrome," is a novel form of acquired cardiomyopathy presenting with clinical features suggestive of acute myocardial infarction (AMI),1,2 often precipitated by sudden, unexpected emotional distress.3 Although AMI exhibits a definite temporal pattern of onset with a peak during winter,4 a summer peak in the occurrence of TTC has been recently reported.5 Because this disease especially affects older women,3 this study intended to verify whether the seasonal variation in the occurrence of TTC may show age-related differences. The analysis included all consecutive patients with TTC admitted between January 2002 and December 2008 to the coronary care units of several referral cardiac centers in Italy.5 All of the enrolled patients fullfilled the requested diagnostic criteria for TTC: transient akinesia or dyskinesia beyond a single major coronary artery vascular distribution; no angiographic evidence of significant coronary artery disease; new electrocardiographic ischemic-like abnormalities (ST-segment elevation or T-wave inversion); and absence of intracranial bleeding, pheochromocytoma, myocarditis, or hypertrophic cardiomyopathy.2 Time of onset of each event was categorized into twelve 1-month intervals for chronobiological analysis, performed by applying a partial Fourier analysis to the time series data using a chronobiological software written for the Macintosh computer (Chronolab, freely available at: Universidade de Vigo, Spain, Bioengineering and Chronobiology Laboratory, http://www.tsc.uvigo.es/BIO/) to the total population and subgroups according to sex and age (<65 and ≥65). This method selects the harmonic that best explains the variance of the time series data. The percentage of the overall variability of the data about the arithmetic mean that is attributable to the fitted rhythmic function (cosine curve by the method of least squares) estimates the goodness of fit of the approximating model, and the F-test statistic is used to test the zero-amplitude null hypothesis (absence of periodicity). The parameters calculated for the overall 1 year in period cosine approximation of the time series data (period of 8,766 hours) were the midline estimated statistic of rhythm (the rhythm-adjusted mean over the time period analyzed), amplitude (half the difference between the absolute maximum and minimum of the fitted curve), and the peak (acrophase) time of the occurrence of the absolute maximum values during the year. Significance levels were assumed for P<.05. During the considered period, the Takotsubo Italian Network database included 112 patients with TTC, mean age 63.6±10.6 and 104 (92.9%) female. The monthly distribution identified the highest number of cases in July (n=22) and the lowest in March (n=2). Chronobiological analysis showed a rhythmic pattern, characterized by a summer peak in July, for total cases, women, and subjects younger than 65 or aged 65 and older (Table 1). The precise mechanism underlying TTC left ventricular dysfunction is still unclear. It is possible that an activation of sympathetic tone may play a role, mediated by high levels of circulating epinephrine (that might trigger a switch in the complex intracellular signal pathway in ventricular cardiomyocytes)6 and high cardiac local release of catecholamines.7 It is a common opinion that TTC especially affects postmenopausal women, and it has been hypothesized that reduction in estrogen levels after menopause might have an indirect or direct effect on the nervous system and the heart, respectively.8 The main finding of this study, conducted on one of the largest populations of TTC patients available in the literature (in a recent review, 9 of 10 studies included 13 to 35 subjects, and one 88),1 is that TTC is equally distributed in subjects younger than 65 and aged 65 and older and that age does not influence the temporal pattern of occurrence, characterized by a peak in summer months. The reasons underlying this seasonal variation are unclear. Various stressor summer events have been evoked,9 and concentrations of urinary catecholamines have been shown to be higher even in healthy women during June and July than in the other months, with a high within- and between-subject variation, not explained by menstrual cycle or behavioral, emotional, or cognitive stress reactions.10 Further studies are needed to confirm these epidemiological observations and to verify the possible potential link between women, summer months, and sympathetic hyperactivity. I have listed everyone who contributed significantly to the work Conflict of Interest: There are no financial, personal, or potential conflicts as they relate to the sponsoring agent, products, technology, or methodolgies involved in the letter submitted for publication for any author. Supported in part by a scientific grant "Finanziamento per ricerca locale—FAR" from the University of Ferrara, Ferrara, Italy. Author Contribution: All contributed significantly to the paper. Sponsor's Role: None.