This retrospective study analyzed the management of 25 patients with hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), or dilated phase of hypertrophic cardiomyopathy (dHCM) treated in the outpatient clinic of the Department of Dental Anesthesiology at Hokkaido University. A total of 87 dental treatment sessions were completed. Intravenous sedation was used significantly more often for patients with HCM than those who had DCM. This seemed to be because dental anesthesiologists expected sedative drugs to suppress hyperdynamic circulatory changes caused by mental stress. Intraoperative complications occurred during 19 treatments. The incidence of circulatory complications increased when participants with DCM also reported dental fear. For participants with HCM who reported dental fear, circulatory complications occurred only when sedation was not used. It is not clear whether complications were related to cardiac function or dental treatment. Therefore, it is important to continually monitor patients with these conditions and to be prepared to handle complications that may arise during dental treatment.