A new evidence-based guideline for pulmonary arterial hypertension (PAH) cautions the use of calcium channel blockers, a commonly used treatment for high blood pressure, in unstable patients due to the potentially fatal side effects associated with the medication. PAH is a life-threatening condition that occurs when the arteries that supply blood to the lungs become constricted, limiting the blood flow to the lungs and, ultimately, causing high blood pressure to develop within the lung arteries. The American College of Chest Physicians (ACCP) Diagnosis and Management of Pulmonary Arterial Hypertension: ACCP Evidence-Based Clinical Practice Guideline provides recommendations for diagnosing and treating PAH. Published in the July issue of CHEST, the peer-reviewed journal of the ACCP, the guideline was developed by a multidisciplinary panel of experts from five medical specialties and is endorsed by the American College of Cardiology Foundation, American College of Rheumatology, American Heart Association, and the Pulmonary Hypertension Association. Panel members recommend against the empiric use of calcium channel blockers or their use in patients who do not respond to acute pulmonary vasodilator testing, citing an increased risk of adverse and potentially fatal events related to the use of the medication. Due to the severity of the disease, the panel also advises genetic testing for patients with a family history of PAH and advance screening for patients with certain chronic diseases who are predisposed to PAH....