Inclusion Criteria:

• Anyone undergoing cardiac catheterization for suspected coronary artery disease over age 18.

Exclusion Criteria:

• 1. Patients currently on long-term antibiotics who cannot stop them for at least 2 weeks prior to providing a stool sample.
• 2. Patients on chronic laxatives who cannot stop for at least 2 weeks prior to stool collection.
• 3. Patients on probiotics and cannot stop for 2 weeks prior to giving a stool sample (yogurt is ok).
• 4. Patients who are unable to provide a stool sample to Mayo Clinic within 24 hours of collection utilizing Fed Ex overnight mail (i.e. people overseas who are unable to provide a sample before leaving the USA.)