Ultrasound cardiography examinations detect victims’ long-term realized and potential consequences after major disasters: a case-control study

Increases in disaster-related diseases and deaths due to degradation of the living environment have been reported in areas located near major disasters. Cardiovascular disease is an example of a disaster-related disease, as came to be noted in Japan when the number of deaths caused by acute myocardial infarction increased following the Great Hanshin-Awaji Earthquake (1995) [1]. An increase in takotsubo cardiomyopathy due to stress was confirmed after the subsequent Niigata-Chuetsu Earthquake (2004). After the Noto Hanto Oki Earthquake (2007), most cases of acute coronary syndrome were confirmed within 7 days of the disaster [2, 3]. Additionally, in the case of the Great East Japan Earthquake (2011), there was an increase in arrhythmia, as well as an increase in heart failure [4]. In our previous study investigating the tsunami disaster area in Watari-gun, Miyagi Prefecture, we found that the number of clinical findings from cardiac ultrasound examination increased every year until the 44th month after the disaster [5]. However, existing work has not yet clarified changes over time in cardiovascular diseases among disaster victims. In the present study, we conducted ultrasound cardiography examinations (UCG) among victims in Watari-gun, Miyagi Prefecture, the area affected by the tsunami caused by the Great East Japan Earthquake. Based on the clinical findings obtained, we then investigated the frequency of cardiovascular diseases occurring as disaster-related diseases and their change over time until the 55th month after the disaster.

Although the impact of major disasters on victims has been studied from various viewpoints, no previous studies have focused on the cardiac function. In the present study, we conducted UCG over a number of years for victims who were not patients at any healthcare facility, and identified the long-term impact on victims of a major disaster for the first time [5]. This study examination can serve as a useful reference when discussing mid-to-long-term post-disaster medical care in the future.

In the present study, the number of people with UCG findings increased until the 44th month after the disaster [5] but then remained stable in the 55th month after the disaster. However, the cases with increased findings were mainly mild ones with less morbid findings. This shows that the potential impact of a major disaster persists even during the disaster recovery phase. Medical examinations, electrocardiograms, and chest X-rays conducted during general checkups do not show any findings until diseases have developed. Because UCG detected minor changes before the onset of cardiac diseases, it is a useful examination to visualize the potential impact of a major disaster on victims.

Environmental changes for the subjects after the disaster can be identified from the background factors included in this study. First, one factor is the decrease in the number of people living in temporary housing that occurred from the 30th to the 44th month after the disaster. In the 55th month, the ratio of temporary housing residents decreased to a low of 21.7%. This shows that the living environment of the subjects changed significantly. Second, dyslipidemia increased significantly from the 18th month to the 30th month. Because over 90% of the residents were in temporary housing during this period, we consider the reason for the increase in dyslipidemia to be the change in diet after moving into temporary housing. It is possible that the increase in the group with findings up till the 44th month was due to the environmental change after the disaster. Additionally, in the multivariate analysis, it was shown that aging, pulse pressure, and course of time were independent risk factors for the group with clinical findings. Especially in the 55th month, despite the average age of the subjects being lower than the past three waves of data collection, the ratio of subjects with clinical findings was significantly higher. This shows that the passage of time after the disaster contributed more to the group with clinical findings than did the subjects’ age.

In this study, an increase in pulse pressure and the passage of time were found to be risk factors for the group with clinical findings. Pulse pressure is regarded as a risk factor for cardiovascular diseases because it indicates the hardening of elastic arteries and an abnormality in cardiac ejection volume. It is possible that, because an increase in pulse pressure promotes heart overload and causes outcomes such as left atrial enlargement, left ventricular hypertrophy, and left ventricular dilatation, its increase over the long term affected the UCG findings [10‐14]. Nakamura M et al. reported that heart failure increased over several weeks after the disaster in the coastal area where it was assumed the victims had higher stress due to the tsunami damage, such as a loss experience. Also, Nakamura A et al. reported that the new-onset heart failure increased among inpatients in the disaster area. In particular, Nakamura A et al. pointed out that there were many cases of heart failure with preserved ejection fraction (HFpEF) as an increase factor [15, 16]. As for an increase factor for the clinical findings in the tsunami disaster area, it is possible that the HFpEF preliminary group was affected by the environmental change and stress of living in the temporary housing due to the tsunami disaster, and heart failure therefore became evident. The left atrial enlargement increased each year in comparison with that of the 18th month after the disaster and peaked at the 44th month after the disaster. Pritchett AM et al. also reported that the left atrial enlargement reflected the chronic left atrial overload due to the diastolic dysfunction [17]. Among the group with clinical findings in the present study, we can assume that the diastolic dysfunction caused by pulse pressure increase, resulted in having the chronic left atrial overload and then enlarged. Although we cannot directly assess the diastolic dysfunction, there is a report that indicated a correlation between the left atrial enlargement and diastolic dysfunction. It is therefore possible that the HFpEF increased in the present study. We can also assume that the mitral regurgitation increased over time due to the left atrial enlargement. Additionally, the average age of the subjects in our study was 70.8 ± 9.3 years, and elderly people accounted for the majority of the sample. This indicates the importance of mental health management for the elderly in the chronic phase of post-disaster medical care. It also suggests that a strong stress reaction, such as survivor’s guilt, can cause cognitive decline, disuse syndrome, and other problems [18‐20]. Such stress is assumed to be difficult to improve through changes in the living environment.

Preventing the onset of cardiovascular disease is an important issue in disaster medical care. Kario, et al. suggests the introduction of disaster cardiovascular prevention (DCAP) risk score / prevention score and disaster cardiovascular prevention network systems [21, 22]. The DCAP risk score makes a significant contribution to detect high-risk patients with cardiovascular disease. Risk items are: 1. Age, 2. Family, 3. House, 4. Community, 5. Hypertension, 6. Diabetes, 7. Medical history of cardiovascular disease. Each item is one point so that it is evaluated with a total of seven points. Any patient with a score of four points or more is categorized to be a high-risk cardiovascular disease patient. Also, any victim with the risk score of four points or more should make an effort to raise the DCAP prevention score to more than six, on a basis of either an evacuation center or individual. DCAP prevention score items are: 1. Sleep, 2. Exercise, 3. Diet, 4. Weigh, 5. Infection, 6. Thrombosis, 7. Medication and 8. Pressure. Each item is one point so that it is evaluated with a total of eight points. Using both types of score is recommended for the disaster medicine to prevent the onset of cardiovascular disease in the acute phase. On the other hand, UCG is a useful examination to visualize the potential impact of the cardiac function, but it is difficult to conduct this for all the victims. Although we did not perform an assessment in the present study, a UCG examination should be conducted for high-risk groups detected by the DCAP score in the stage when the victims are living in temporary housing complexes. A remarkable increase in the group with clinical findings continued until the 44th month after the disaster in the present study. We therefore think that we should actively conduct preventive measures and medical checkups against cardiovascular disease after they have moved to temporary housing. A long-term support system is necessary to prevent the increase of cardiovascular diseases, while government, local medical institutions, and medical support teams from outside the affected areas cooperate together and help functional recovery of local medical institutions.

The data in this study were collected after the population had moved into temporary housing, and we did not compare our findings with those from data collected before the disaster or at the stage of living in shelters. For this reason, the impact of a major disaster itself on victims is not taken into account. Findings in the present study cannot be specific for the disaster because of a lack of data before the disaster. It is however possible that narrow and unfamiliar housing environments like temporary housing complexes contributed to the change.

It is possible that the UCG can become a useful examination to visualize the potential impact of a major disaster on the cardiac function of victims. Victims with clinical findings continued increasing not only during the acute phase after a disaster but also in the long term. We therefore need to keep this in mind, and note that it is important to establish a support system to control cardiovascular diseases from the early stage of disaster.