Statin and Angiotensin-converting Enzyme Inhibitor on Symptoms in Patients With SCAD

Overview

An emerging cause of heart attack in young women is a dissection (or tear) in the coronary arteries. Many of these young women continue to have chest pain long after the tear has healed and this is thought to be due to problems with their small blood vessels of the heart (or microcirculation). We want to determine whether commonly used medications for coronary artery disease including statins (for cholesterol) and angiotensin-converting enzyme inhibitors (for blood pressure) reduce chest pain and improve small vessel function in these patients.

In patients with spontaneous coronary artery dissection (SCAD), many continue to have ongoing signs and symptoms of ischemia after the dissection has healed. Further, 1 in 5 women will experience recurrent SCAD in long-term follow-up. To date, no study has investigated the pathophysiologic mechanism behind ongoing symptoms or recurrence of SCAD, but microvascular coronary dysfunction (MCD) has been suggested. Coronary reactivity testing (CRT) is an invasive procedure currently being done in MCD patients as the gold standard technique. In particular, a coronary flow reserve (CFR) \< 2.5 has been shown to be both diagnostic of the condition and prognostic of a 2 fold increased risk of cardiac events. Please see below for a detailed description of CRT. In brief, a dual temperature and pressure sensor tipped wire by Radi Medical Systems (St Jude Medical, St Paul, MN) will be placed into the dissected and non-dissected coronary arteries of the patient. This will measure CFR by thermodilution and will also allow the measurement of the index of microcirculatory resistance (IMR). IMR has been found to correlate well with true microvascular resistance. In addition to a lack of diagnostic strategies, there is a paucity of research into therapeutic strategies. Most women are conservatively managed with medications, however, there is no consensus as to which pharmacologic therapies should be used. Case reports have suggested benefit with antiplatelet agents (e.g. aspirin) and beta-blockers (reduction of arterial wall shear stress). To date no study has investigated the effects of statins or Angiotensin Converting Enzyme Inhibitors (ACEIs) in SCAD patients. Both agents have been studied in the MCD population and been found to reduce angina frequency and improve CFR after 16 weeks. Purpose: To measuring the CFR and IMR in 40 SCAD patients with ongoing chest pain who are at least 3 months from their dissection to determine the proportion with microvascular dysfunction and to investigate prospectively whether the addition of an ACEI or a statin to usual care in patients with ongoing chest pain and a CFR \<3.0 improves chest pain frequency by Seattle Angina Questionnaire (SAQ) at 16 weeks compared to placebo. Hypothesis: We hypothesize that the average CFR in patients at least 3 months out from their SCAD will be \<2.5 and that their IMR will be abnormal. Further, we hypothesize that the addition of either an ACEI and/or statin will improve chest pain frequency by at least 20 points on the SAQ at 16 weeks compared to placebo.

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Outcomes