Use of Stress Testing for the Risk Stratification of Patients at Low to Intermediate Event Risk According to the PAIN Pathway Algorithm

Coronary artery disease is a progressive disease with a wide range of clinical presentations. In some individuals, the development of angina is the fi rst warning sign, but in others, acute coronary syndrome, unheralded myocardial infarction, or sudden death is the initial clinical presentation. The atherosclerotic fi ndings that correspond with these clinical presentations also vary widely. For example, it has been demonstrated that among patients presenting with acute coronary syndromes, approximately 30%of such patients have triple-vessel disease, 30% have double-vessel disease, 30% have single-vessel disease, and approximately 10% are without evidence of signifi cant atherosclerotic narrowing [1–3]. Moreover, various studies have demonstrated that anginal symptoms and inducible myocardial ischemia are not tightly coupled. Patients with typical angina frequently do not manifest inducible ischemia, and conversely, patients with inducible ischemia often do not manifest chest pain (i.e., they manifest “silent ischemia”) [4, 5]. For these reasons, the astute clinician learns not to rely solely on clinical evaluation in the workup and follow-up of patients who present with chest pain. Rather, objective measures of cardiac risk, such as the degree of abnormality during cardiac stress testing, is used by clinicians as a decision guide for the clinical management of patients who present with clinical symptoms.

Making a correct diagnosis in the setting of new-onset chest pain is especially important because the a priori risk for signifi cant atherosclerosis is higher in such patients and because progression to very early myocardial revasculariza-tion is very important for those having chest pain due to unstable or ruptured atherosclerotic plaque. Accordingly, the St. Luke's-Roosevelt Hospital Center “chest pain pathway” is designed to implement a rapid-response approach to patients presenting to our hospital with acute chest pain. This pathway includes specifi c indications for the immediate referral to our cardiac catheterization laboratory for those with acute chest pain. These include the immediate referral of patients who present with ST-elevation myocardial infarction or have prolonged chest pain in association with ST changes and/or increase in cardiac enzymes. This pathway has the acronym PAIN, and it is described at length in Chapter 2. Patients with low to intermediate risk of cardiac events by our pathway include patients with transient chest pain without defi nitive ST changes or elevations in cardiac enzymes and without signs of new heart failure or hemodynamic instability (see Chapters 12 and 13).