Cardiovascular Disease｜Research Team

Weighty responsibility as a doctor and the enjoyment of challenging work surpassing it

In classes and initial training during my medical student days, life-saving treatments and acute-phase management seemed very dynamic and appealingIn acute-phase treatment, the patient’s prognosis is determined by the doctor's judgment. When deciding to do work that impacts the lives of patients, I felt a weighty responsibility as a doctor. Moreover, I found the work very enjoyable and challenging. Cardiovascular diseases are not only life-threatening but also occur suddenly. I also had a strong desire to overcome this situation.
When I was actually involved in the treatment of acute myocardial infarction as a resident doctor and tried firsthand to insert a catheter, my interest in cardiovascular medicine increased. At graduate school, I became addicted to the joy of intravascular imaging and for which my interest grew exceedingly.

If the mechanism of unstable plaque formation and its characteristics are known, recurrence can be prevented in nearly 100% of the cases

At present, we are conducting research to explain the mechanism of coronary plaque destabilization and are exploring some useful indexes. Acute coronary syndrome is based on a tissue called "atheroma plaque" formed from intima thickening of blood vessels and invasion of cholesterol. Atherosclerosis itself can occur in anyone, but not all of them cause myocardial infarction. Unstable plaques can collapse into thrombosis obstructive lesions, leading to events such as myocardial infarction and unstable angina. If we can explain and predict this in advance, unforeseen circumstances can be prevented. I think that if we can find the cause of development of unstable plaque development and the characteristics of the plaque morphology especially for patients who have had myocardial infarction once, we can prevent its recurrence by appropriately dealing with it.

Recurrence can be prevented if early diagnosis is made possible with intravascular imaging

I have been conducting cohort studies for explaining prognosis and prediction factors of patients for more than 10 years since my graduate school days. I have verified the prognosis of patients treated for coronary artery diseases and have been presenting the characteristics of patients who have suffered a relapse and those who have not. Moreover, I have also published papers comparing intravascular imaging data with patient backgrounds. The key to these research works is “intravascular imaging”.

Intravascular imaging is a technique in which a catheter is inserted into a blood vessel and the plaque of the coronary artery is projected by using various devices such as ultrasound and infrared rays. This is also one of the techniques in which Japanese doctors are proficient. In my research, I have examined the walls of blood vessels, paying particular attention to the destabilization of atherosclerosis. IVUS (intravascular ultrasonography) and OCT (optical coherence tomography) are often used in endovascular imaging. When I studied abroad in 2012, I investigated a new intravascular imaging modality called NIRS (near-infrared spectroscopy that non-invasively measures cerebral oxygen metabolism and cerebral circulation by using near-infrared light with excellent biological permeability). If we can make early diagnosis of vulnerable plaque, we can provide appropriate treatment at an early stage. After conducting treatment for these coronary artery diseases, risk management can be actively carried out to prevent recurrence. Keeping the heart in good health requires not only the treatment of the lesions, but also a long-term preventive strategy such as preventing the occurrence of individual lesions as well as recurrence.

Searching for recurrence prediction factors with the latest intravascular imaging devices and accumulated data

Going forward, I think non-invasive imaging techniques such as CT and MRI will be used increasingly in the future; however, these techniques have not yet caught up with plaque research in intravascular imaging.

The multiple intravascular imaging devices at our hospital have been used to accumulate various data of patients over an extended period of time in collaboration with other teams. For patients who have received catheter treatment at our hospital at any one time, we would like to visualize and stratify (dividing in groups) the risks through imaging to determine the probability of recurrence in the future and offer thorough preventive medical care according to the risk.
Currently, in our database, we are paying particular attention to the recurrence pattern.

For example, patients who develop heart failure and patients who suffer relapse due to stent restenosis are clearly in different patient groups. If these recurrence patterns can be determined at an early stage, not only can coronary artery diseases be managed, but recurrence of all heart diseases may also be prevented. Furthermore, our goal is to be able to stratify the risks not only by the background factors of the patients but also by the instability of the plaque itself and the site of its occurrence. For example, most patients with acute coronary syndrome (ACS) have nonculprit lesions, with an average of 3-4 plaques of abundant capacity in their coronary tree. It is important to find out whether the plaque is stable or unstable and life-threatening. Based thereon, it is also important to consider the target values for preventive strategy and risk management treatment of the patients.

The pumping function of the heart has a great impact on the coronary blood flow. Given that the heart failure pandemic in an aging society is regarded as a critical issue, there is no doubt that coronary artery management and prevention of recurrence of coronary artery diseases are urgent issues from the standpoint of preventing heart failure.

In fact, out of 100 people who are treated for acute coronary syndrome, nearly 10% thereof will have a recurrence or some coronary event. Also, if a patient has a large myocardial infarction, the probability of the patient suffering from heart failure 10 years later will be higher. If the coronary event recurrence can be prevented altogether, apart from maintaining quality of life free of angina, it may be possible to maintain cardiac function and prevent the onset of heart failure.

At our hospital, treatment with a catheter is not the end. We conduct medical treatment and research while paying constant attention to protecting the health of the patients’ heart, including prevention.

In the phase of data aggregation and dissemination phase of Asian people and establishing diagnosis and treatment

While Europe and the United States are leaders in intravascular imaging of vulnerable plaque, this field is still under development with many unknown factors. However, it is said that Japanese people are by far the best in the world in terms of imaging techniques, with regard to the clarity of images and level of PCI (percutaneous coronary intervention) techniques.

While data is collected in all countries, tests and treatments required differ depending on the race, frequency of onset, and culture rooted in the region. It is necessary to establish diagnosis and treatment for Japanese and Asians with reference to Western data. We are at the phase of aggregating and disseminating data unique to Japanese people from the database of our hospital.

From explanation of pathological conditions to development of treatment strategies with blood vessel imaging, a technique with high expectations

When a patient complains that he has a pain in his chest, my desire is to do something about it. If a patient who has developed myocardial infarction, after having been treated for a stenotic lesion says, “Doctor, my pain has gone!” I would feel a deep sense of satisfaction. At the same time, it creates a strong desire in me to find out the cause and how to prevent it from happening in the future, which translates into enthusiasm for research.

atheter intervention can drastically improve the patient's symptoms. However, understanding the characteristics of unstable plaque and developing a treatment strategy based thereon is still areas to be addressed in the future. By combining the valuable database that our predecessors have built up over time with the imaging data which is my forte, I intend to build a treatment strategy approach at an early stage and aim to achieve “zero coronary artery disease event” where patients once treated for coronary artery disease at our hospital will never experience a recurrence. In addition, since we have been nurturing capable new doctors, we would like to continue to disseminate to the world data and research results unique to Japanese and Asians together with their referring to data from Europe and the United States.

he research of intravascular imaging, which allows us to acquire images of coronary plaques, is a groundbreaking and very interesting field. I am working diligently every day to clarify the pathology and building treatment strategy thereon., I invite people who are interested in heart, blood vessels, myocardial infarction, and acute coronary syndrome to participate in the research with me.

Tomotaka Dohi