Chest Pain Perception and Capsaicin Sensitivity

Chest discomfort is considered the hallmark of myocardial ischemia and as such is an important clinical warning sign of myocardial infarction (MI). The ability to sense ischemic chest discomfort appears to be impaired in a substantial minority of the population and such individuals are presumably at increased risk for unrecognized MI. While the mechanism(s) responsible for the perception of chest pain associated with myocardial ischemia are still not fully understood, studies suggest that the transient receptor potential vanilloid-1 (TRPV1) plays a key role in this process. This nociceptor, which is known to mediate pain sensation in the skin and elsewhere in the peripheral nervous system, has also been found on the outer surface of the heart and has been shown to respond to ischemic stress in this organ.

The purpose of this study is to determine whether there is a positive correlation between the ability to sense chest pain in the context of myocardial ischemia and the ability to sense discomfort associated with the topical application of the TRPV1 agonist capsaicin (the active ingredient on hot chili peppers). Patients undergoing clinical elective balloon angioplasty of a coronary stenosis will be asked to quantify the subjective intensity of any chest pain they feel during a standardized episode of myocardial ischemia produced by a one-minute coronary balloon occlusion, using a previously-validated numeric rating scale. The same patients will subsequently be asked to grade the subjective intensity of cutaneous discomfort resulting from application of a capsaicin-containing patch (Capzasin-HP Cream, an over-the-counter product approved for topical application to treat muscle and joint aches) to the forearm. The goal will be to determine whether an association can be demonstrated between the subjective perception of ischemic chest pain during coronary balloon occlusion and cutaneous capsaicin sensitivity. Such an association could have considerable clinical value, as it might allow physicians to prospectively assess an individual's ability to perceive myocardial ischemia/infarction by assessing his/her subjective response to the topical application of capsaicin.

Inclusion criteria

Subjects will consist of patients who have undergone clinically-indicated percutaneous coronary intervention (PCI) for the treatment of coronary artery disease.

Exclusion criteria

Clinically unstable patients, such as those undergoing emergency PCI, patients with documented hypersensitivity to capsaicin will be excluded and patients who have used a capsaicin-based product within the last 3 months will be excluded. Patients in whom it would be inadvisable for any reason to conduct a one-hour research study at a follow-up visit after PCI will also be excluded.