Takotsubo syndrome was described in Japan in 1990 (2), in Europe in 1997 and in the United States in 1998 (3, 5). Few international studies and no Norwegian studies have been made of its prevalence in the population. In the period 2010–2016, we found an average prevalence of 3.3 per 100 000 inhabitants per year. In comparison, the prevalence of myocardial infarction in Norway is approximately 260 per 100 000 inhabitants per year (6). The prevalence can alternatively be estimated as the number of patients with Takotsubo syndrome as a proportion of all patients who are examined with coronary angiography because of suspected acute myocardial infarction. We found 2.3 % for the years 2014–2015, which tallies with the findings made by others of 1.7–2.2 % (7, 8, 9). In our material, the number of patients with Takotsubo syndrome increased by 19.9 % each year. There are many reports of an increase in the number of patients with Takotsubo syndrome, including a tripling over six years in the United States (7, 10). The causes of this increase may include higher awareness of the disorder, the greater number of acute patients examined with coronary angiography and changes in the gender and age distribution of the patient group.
Takotsubo syndrome is a differential diagnosis for acute myocardial infarction. The diagnosis can only be made with coronary angiography at an early stage of the course of the disorder. Figures from the Norwegian Myocardial Infarction Register have shown that more than one-third of the MI patients in 2013 were not examined with coronary angiography (6). Elderly women and patients with serious non-cardiovascular diseases are underrepresented among those referred to coronary angiography (11). There is thus a risk of underdiagnosis and misdiagnosis of patients with Takotsubo syndrome.
The patients were predominantly women over 60 years, and less than 2 % were younger than 50 years. This tallies with findings from registry studies (3, 7). A Swedish study found that patients with Takotsubo syndrome did not have an elevated prevalence of cardiovascular risk factors, but a higher prevalence of chronic obstructive pulmonary disorder (COPD) (12). In our study, the triggering factors were evenly distributed among somatic and non-somatic symptoms/disorders, while 24 % of the patients had no detectable triggering cause. This tallies with findings made by others (3).
The symptoms of Takotsubo syndrome and acute myocardial infarction are often identical. The disorders cannot be distinguished with the aid of ECG and troponin values. All our patients had elevated troponin values. Some authors claim that patients with Takotsubo syndrome have a lower troponin response than MI patients, but an earlier study showed no difference (4). Transthoracic echocardiography may detect abnormal regional contractions, but it is often difficult to locate the anatomical apex, especially in elderly and ill patients (1). No satisfactory non-invasive method is available, and coronary angiography with ventriculography remains the gold standard in the investigation of Takotsubo syndrome (3, 5). The use of ventriculography varies between hospitals, especially in the case of acute myocardial infarction. International consensus documents recommend direct angiography of the left ventricle when coronary angiography for acute coronary syndrome shows open arteries (3–5). Magnetic resonance tomography (MR) can demonstrate the extent of the myocardial affection in case of Takotsubo syndrome (5, 13). Our experience indicates that the myocardial function may improve or normalise in no more than 1–2 days in some patients and that diagnostics therefore ought to be undertaken at an early stage of the disorder.
In 39 % of the admissions, the patient sustained complications that required treatment during the hospitalisation, and in 11 % the patient suffered a serious heart failure. This tallies with findings in other publications, in which up to 52 % of the patients sustained complications (3, 4). Cardiogenic shock and ventricular fibrillation are common causes of death from Takotsubo syndrome (3, 4). Hospital mortality is reported to be 2–5 % (3, 7, 14, 16).
Six (7 %) patients died after having been diagnosed with Takotsubo syndrome, and there was a predominance of non-cardiovascular deaths. In an international register, the long-term mortality was higher: 5.6 % per year.
A Swedish study showed that long-term mortality was higher than in the general population, and equal to the mortality from chronic coronary heart disorders (12).
The pathophysiological mechanisms for myocardial dysfunction in Takotsubo syndrome have not been clarified. High sympathetic tone and endogenous catecholamines are assumed to be key factors, and intravenous inotropic sympathomimetics may trigger a similar reaction (4, 5, 15). Most likely, a focal microvascular constriction is triggered, which in turn may cause reduced contraction in parts of the myocardium (5). The location of myocardial dysfunction varies, including in one and the same person with multiple episodes (4, 7). A registry study detected a small group of patients who experienced Takotsubo syndrome after a positive emotional reaction and had akinesia with a primarily mid-ventricular location, so-called 'happy heart syndrome' (5). The most frequent forms, with extension and akinesia located in the apex or middle section of the ventricle, are fairly conspicuous. In 1–2 % of the patients two rarer forms have also been described, involving isolated akinesia in the basal or lateral sections of the left ventricle (3, 4). MR examinations have shown that Takotsubo syndrome also may involve the right ventricle (3, 5, 13).
No causal treatment is available, and no randomised studies of drugs for Takotsubo syndrome have been undertaken. Caution is recommended in use of sympathomimetic inotropic drugs. Levosimendan may be an alternative in case of left ventricular failure (3). ACE inhibitors or AII receptor inhibitors may improve the prognosis (5). Beta blockers have no documented prognostic or preventive effect for Takotsubo syndrome (3, 17).
This study includes a relatively high number of patients with Takotsubo syndrome from a specific geographic area, with a long follow-up period and complete follow-up. However, the study included only patients from a single hospital, and subjective interpretation of diagnostic criteria may have had an effect on inclusion in the study.