Which suffix indicates "pertaining to the heart"?

The suffix that indicates "pertaining to the heart" is -cardiac. This suffix is derived from the Greek word "kardia," which means heart. It is commonly used in medical terminology to describe conditions, procedures, or characteristics related specifically to the heart. For instance, "myocardial" refers to anything related to the heart muscle, and "pericardial" pertains to the membrane surrounding the heart.

In contrast, the other suffixes do not specifically relate to the heart. -Angio refers to blood vessels or lymphatic vessels, -thoracic pertains to the chest cavity or thorax, and -vascular relates to blood vessels generally. Therefore, -cardiac is the appropriate choice when discussing aspects directly associated with the heart.