Chest Pain Perception and Capsaicin Sensitivity in Patients With Acute Cardiac Ischemia

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).

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 urgent or emergent balloon angioplasty of an acute 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. This study is designed to be a companion project to Project 1029 Chest Pain Perception and Capsaicin Sensitivity, which is collecting the same data from clinically stable patients undergoing elective cardiac catheterization.

Subjects will undergo the cutaneous capsaicin test at the time of the study visit. A one inch ribbon of Capzasin-HP Cream (0.1%) will be applied to the skin on the forearm of the non-dominant arm. Subjects will be asked to assign a numerical score to the maximum intensity of any cutaneous discomfort experienced during the subsequent 30 minutes, from 0 ("no discomfort") to 10 ("the worst discomfort imaginable"). The cream will then be removed by washing the affected arm with cold water. Efforts will then be made to examine the association between the pain score documented in response to the cutaneous capsaicin test with the pain score obtained during coronary balloon occlusion. This method should allow an individual's subjective sensitivity to the TRPV1-mediated noxious stimulus of myocardial ischemia to be compared with his/her sensitivity to the TRPV1-mediated noxious stimulus of cutaneous capsaicin in extra-cardiac tissues.

Each patient will be asked to rate their discomfort at the application site based on a 10 point numerical rating scale for cutaneous discomfort, ranging from 0 ("no discomfort") to 10 ("the worst discomfort imaginable")

Patients are asked to rate their chest pain on a scale of 0 "No pain" to 10 "Worst pain imaginable" during balloon inflation during PCI.

Inclusion Criteria: Subjects will consist of patients who have undergone clinically-indicated PCI for the treatment of coronary artery disease. This study will include clinically unstable patients, such as those undergoing emergency percutaneous coronary intervention (PCI) for acute myocardial infarction, etc. Exclusion Criteria: 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