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Impact of Earthquakes on Takotsubo Cardiomyopathy
To the Editor: Acute physical and psychological stress may provoke cardiovascular events, and although earthquake-associated increases in sudden death and acute myocardial infarction have been reported,1-2 the effect of such conditions is unknown for stress-induced cardiomyopathy (Takotsubo cardiomyopathy).3-4 On October 23, 2004, central Niigata, Japan, was shaken by a series of 3 strong earthquakes, with about 90 large aftershocks during the following week.
Methods
We retrospectively investigated the incidence of acute cardiovascular events, including Takotsubo cardiomyopathy, acute coronary syndrome, and sudden death, from September 25, 2004, to November 19, 2004, in 8 hospitals that treat most patients with such disorders in the area affected by the earthquake. These results were compared with the corresponding 8-week periods in 2003 and 2002. Event onset was defined as the time when symptoms first appeared. Takotsubo cardiomyopathy was diagnosed from characteristic transient apical dysfunction of the left ventricle by echocardiography, left ventriculography, or both, and sequential electrocardiographic changes of ST-segment elevation followed by deep T-wave inversion in the absence of coronary artery disease.3-4 Sudden cardiac death was defined as death that occurred within 1 hour after acute onset of symptoms, with no probable cause of death suggested from medical records. All diagnoses were independently confirmed by 2 cardiologists.
The population size of this area was stable from 2002 through 2004. The number of daily events for each week following the earthquake was compared separately with the 4 weeks prior to the earthquake and with the corresponding 8 weeks in 2003 and 2002 using the Kruskal-Wallis test followed by the Steel-Dwass test. Analyses were performed with SPSS, version 12.0 (SPSS Inc, Chicago, Ill) and R-language, version 2.0.1 (R Foundation, Vienna, Austria). P<.05 was considered statistically significant.
Results
The number of cardiovascular events markedly increased to 52 in the week following the earthquake, with a daily median (range) of 6 (0-21) compared with 2 (0-4) in the prior 4 weeks (P = .03), 2 (0-5) in 2003 (P = .01), and 1 (0-6) in 2002 (P = .01) (Figure). The number of cases of sudden death increased in the week after the earthquake, with a daily median of 3 (0-6) compared with 1 (0-3) in the prior 4 weeks (P = .15), 0.5 (0-3) in 2003 (P = .07), and 0 (0-3) in 2002 (P = .04). Of the 14 cases of acute coronary syndrome presenting during the week after the earthquake, the median daily number did not significantly differ from the prior 4 weeks, although 4 of the 14 cases occurred on the day of the earthquake.
Takotsubo cardiomyopathy increased in the 4 weeks after the earthquake to 25 cases compared with only 1 case reported in the 4 weeks before the earthquake, none in 2003, and 1 in 2002. The number of events during the week after the earthquake was a daily median of 1 (0-11) compared with 0 (0-1) in the prior 4 weeks, 0 in 2003, and 0 (0-1) in 2002 (P<.001 for each comparison). The first case occurred immediately after the first shock, and 10 further cases began within a few hours. New cases continued to occur until day 19 (16 in the first week, 5 in the second week, 4 in the third week) as aftershocks continued. Although 10 patients (40%) developed life-threatening heart failure, all recovered within several weeks following the improvement of apical dysfunction.
Comment
There was a marked increase in the incidence of Takotsubo cardiomyopathy in Niigata, apparently as a result of the earthquakes. This disease is thought to be a stress-induced disorder. Elevated catecholamine levels in patients with stress-induced cardiomyopathy have recently been reported,3 and such a surge in response to physical or psychological stress may have been the mechanism following the earthquakes. While sudden death triggered by earthquakes has been believed to be related to atherosclerotic cardiovascular disease,1, 5 we observed a disproportionate increase in sudden death compared with the increase in cases of acute coronary syndrome that is consistent with a relationship to Takotsubo cardiomyopathy.
Two limitations to this study need to be considered. First, there is the potential for ascertainment bias. However, Takotsubo cardiomyopathy has been very familiar to Japanese cardiologists for many years. In this study, 94.7% of patients presenting with either acute coronary syndrome or Takotsubo cardiomyopathy had their diagnosis confirmed by angiography. Second, autopsies were not performed for the cases of sudden death.
We conclude that physicians should be aware of the potential for Takotsubo cardiomyopathy following catastrophic events.
Author Contributors: Dr Watanabe had full access to all of the data in the study and takes responsibility for the integrity of the data and accuracy of the data analysis.
Study concept and design: Watanabe, Kodama, Aizawa.
Acquisition of data: Watanabe, Nakamura, Nagai, Sato, Okabe.
Analysis and interpretation of data: Watanabe, Okura, Chinushi, Kodama.
Drafting of the manuscript: Watanabe.
Statistical analysis: Watanabe, Tanabe.
Obtaining funding: Okura, Aizawa.
Administrative, technical, or material support: Aizawa.
Study supervision: Aizawa.
Conflict of Interest: None reported.
Financial Disclosures: None reported.
Funding/Support: This work was supported by research grants from the Ministry of Health, Labor and Welfare, Japan.
Role of the Sponsor: The funding source had no role in the design and conduct of the study; in the collection, management, analysis, and interpretation of the data; or in the preparation, review, or approval of the manuscript.
Acknowledgment: We thank Tsuyoshi Yoshida, MD, PhD, Department of Internal Medicine, Tokamachi Hospital, Tokamachi, Japan; Manabu Hayashi, MD, PhD, Cardiovascular Center, Tachikawa General Hospital, Nagaoka-City, Japan; Satoshi Watanabe, MD, PhD, Division of Emergency Medicine, Nagaoka Red Cross Hospital, Nagaoka City, Japan; Akemitsu Nasuno, MD, PhD, Division of Cardiology, Kariwagun General Hospital, Kashiwazaki, Japan; Osamu Kuwahara, MD, PhD, Department of Internal Medicine, Koide Hospital, Uonuma, Japan; Akihiro Obata, MD, PhD, Division of Cardiology, Ojiya General Hospital, Ojiya, Japan; and Hirohiko Kuwano, MD, PhD, Division of Cardiology, Muikamachi Hospital, Minamiuonuma, Japan; who all provided valuable assistance for acquisition of data without any compensation from the funding sponsor.
Hiroshi Watanabe, MD, PhD
hiroshi7{at}med.niigata-u.ac.jp
Makoto Kodama, MD, PhD;
Yuji Okura, MD, PhD;
Yoshifusa Aizawa, MD, PhD
Division of Cardiology
Naohito Tanabe, MD, PhD
Division of Health Promotion
Masaomi Chinushi, MD, PhD
School of Health Sciences
Niigata University Graduate School of Medical and Dental Sciences
Niigata, Japan
Yuichi Nakamura, MD, PhD
Division of Cardiology
Nagaoka Chuo General Hospital
Tsuneo Nagai, MD, PhD
Division of Cardiology
Nagaoka Red Cross Hospital
Masahito Sato, MD, PhD;
Masaaki Okabe, MD, PhD
Cardiovascular Center
Tachikawa General Hospital
Nagaoka, Japan
1. Leor J, Poole WK, Kloner RA. Sudden cardiac death triggered by an earthquake. N Engl J Med. 1996;334:413-419.
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2. Suzuki S, Sakamoto S, Koide M, et al. Hanshin-Awaji earthquake as a trigger for acute myocardial infarction. Am Heart J. 1997;134:974-977.
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3. Wittstein IS, Thiemann DR, Lima JA, et al. Neurohumoral features of myocardial stunning due to sudden emotional stress. N Engl J Med. 2005;352:539-548.
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4. Kawai S, Suzuki H, Yamaguchi H, et al. Ampulla cardiomyopathy ('Takotusbo' cardiomyopathy)–reversible left ventricular dysfunction: with ST segment elevation. Jpn Circ J. 2000;64:156-159.
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5. Kario K, Matsuo T, Kobayashi H, et al. Earthquake-induced potentiation of acute risk factors in hypertensive elderly patients: possible triggering of cardiovascular events after a major earthquake. J Am Coll Cardiol. 1997;29:926-933.
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Letters Section Editor: Robert M. Golub, MD, Senior Editor.
JAMA. 2005;294:305-307.
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P<.001 compared with 2002 and 2003; 
P<.001 compared with prior 4 weeks; 
P=.002 compared with prior 4 weeks; ||P=.02 compared with prior 4 weeks.