medicine

• The book "Step-Up to Medicine" covers various medical topics encountered during the clinical years of medical school and corresponding NBME shelf examinations
• The fifth edition of "Step-Up to Medicine" has been extensively revised and edited based on feedback from students, residents, and faculty
• The book emphasizes that it is not a substitute for individual patient assessment based on healthcare professionals' examination of each patient and consideration of various factors unique to the patient
• Continuous, rapid advances in medical science and health information require independent professional verification of medical diagnoses, indications, appropriate pharmaceutical selections, dosages, and treatment options
• Stable angina pectoris is due to fixed atherosclerotic lesions that narrow the major coronary arteries, leading to an imbalance between blood supply and oxygen demand
• Major risk factors for stable angina include diabetes mellitus, hyperlipidemia, hypertension, cigarette smoking, age, family history of premature coronary artery disease, low levels of high-density lipoprotein, end-stage renal disease, human immunodeficiency virus infection, history of mediastinal radiation, obesity, sedentary lifestyle, stress, and excess alcohol use
• Prognostic indicators of coronary artery disease (CAD) include left ventricular function (ejection fraction [EF]) and the severity/extent of ischemia in the vessels involved
• Clinical presentations of CAD can include asymptomatic, stable angina pectoris, unstable angina, myocardial infarction (MI) (either NSTEMI or STEMI), and sudden cardiac death
• Typical anginal chest pain is substernal, worsens with exertion, and improves with rest or nitroglycerin
• Diagnosis of CAD involves a resting ECG, stress test, and stress myocardial perfusion imaging after IV administration of a radioisotope such as thallium 201 during exercise
• Exercise stress ECG is an ideal initial test if able to exercise and have a normal resting ECG; stress echocardiography is favored by many cardiologists over stress ECG as it is more sensitive in detecting ischemia
• A stress test is generally considered positive if the patient develops ST-segment depression, chest pain, hypotension, or significant arrhythmias during exercise
• Cardiac catheterization with coronary angiography is the definitive test for CAD and is often performed with concurrent PCI or for patients being considered for revascularization with CABG
• Cardiac catheterization provides information on hemodynamics, intracardiac pressure measurements, cardiac output, oxygen saturation, and is almost always performed with coronary angiography for visualization of coronary arteries
• Coronary angiogram is used to identify patients with severe coronary disease to determine if revascularization is needed
• Revascularization with PCI involving a balloon and/or a stent can be performed at the same time as the diagnostic procedure
• Coronary stenosis >70% may be significant as it can produce angina
• Risk factor modification for CAD includes smoking cessation, vigorous BP control, reduction in serum cholesterol, strict glycemic control for diabetes, weight loss, exercise, and diet adjustments
• Standard of care for stable angina includes drugs that improve mortality like aspirin and high-intensity statins, and drugs that relieve angina such as β-blockers, nitrates, calcium channel blockers, and ranolazine
• Side effects of β-blockers include erectile dysfunction in males and inability to increase heart rate in response to exercise
• Side effects of nitrates include headache, orthostatic hypotension, tolerance, and syncope
• Medical therapy for CAD includes aspirin, lipid-lowering therapy with statins, β-blockers, nitrates, and calcium channel blockers
• Revascularization methods for stable CAD are controversial, with studies suggesting no improvement in mortality and MI compared to medical therapy alone
• Management decisions for CAD depend on the severity of the disease, with different approaches for mild, moderate, and severe cases
• Unstable angina is characterized by decreased coronary flow due to thrombosis, hemorrhage, or plaque rupture, and it may lead to total occlusion of a coronary vessel
• Patients with unstable angina should be stabilized with medical management before stress testing or undergo cardiac catheterization initially
• Treatment for unstable angina includes hospital admission with continuous cardiac monitoring, IV access, supplemental oxygen if hypoxic, pain control with nitrates and opioids, and aggressive medical management with dual antiplatelet therapy, heparin, β-blockers, and other medications
• The ESSENCE trial showed that in unstable angina and non–ST-segment elevation MI, risk of death, MI, or recurrent angina was lower in the enoxaparin group than in the heparin group at 14 days, 30 days, and 1 year
• Thrombolytic therapy (fibrinolysis) has NOT been proven to be beneficial in unstable angina, only indicated in STEMI when no access to urgent catheterization for PCI
• More than 90% of patients improve within 1 to 2 days with the above medical regimen for cardiac catheterization/revascularization
• The choice of invasive management (early catheterization/revascularization within 48 hours) versus conservative management is controversial
• If patient responds to medical therapy for unstable angina, perform a stress test to assess the need for catheterization/revascularization
• If medical therapy fails to improve symptoms and/or ECG changes indicative of ischemia persist after 48 hours, proceed directly to catheterization/revascularization
• After acute treatment for myocardial infarction, continue aspirin, β-blockers, nitrates, and statin therapy, and reduce risk factors like smoking, weight, diabetes, HTN, and hyperlipidemia
• The CARE trial showed that patients with prior history of MI treated with statins had reduced risk of death, stroke, and need for CABG or coronary angioplasty
• Variant (Prinzmetal) Angina involves transient coronary vasospasm usually accompanied by a fixed atherosclerotic lesion or can occur in normal coronary arteries
• Myocardial Infarction is due to necrosis of myocardium from an interruption of blood supply, often due to acute coronary thrombosis
• In MI, aspirin, ticagrelor, β-blockers, and ACE inhibitors are the only agents shown to reduce mortality
• ST-segment elevation indicates an infarction 75% of the time, while ST-segment depression indicates an infarction only 25% of the time
• Cardiac enzymes like Troponins and CK-MB are used for diagnosing myocardial injury, with Troponins being more sensitive and specific