『Cardiology - Cardiovascular Disease and Cancer』のカバーアート

Cardiology - Cardiovascular Disease and Cancer

Cardiology - Cardiovascular Disease and Cancer

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 Cardiovascular Disease in CancerI. Cardiotoxicity of Radiation Therapy to the ThoraxPrevalence and Significance: Radiation therapy, while improving survival in patients with thoracic malignancies (e.g., Hodgkin lymphoma, early-stage breast cancer), has led to cardiovascular disease becoming "the most common nonmalignant cause of death in patients treated with chest radiation therapy, accounting for 25% of deaths in survivors of Hodgkin lymphoma."Mechanism and Onset: Thoracic irradiation damages all cardiac cells and structures, including the "pericardium, myocardium, valves, coronary and peripheral vasculature, and conduction system." Clinical disease typically presents "two to three decades after treatment," though some manifestations can occur earlier.Increased Risk Factors: The risk of radiation-induced cardiac injury is heightened in patients receiving "concomitant anthracyclines or trastuzumab." Contemporary radiation techniques aim to "limit total dosage and field size" to decrease complications.Spectrum of Cardiovascular Diseases (Table 42):Pericardial Disease:Acute pericarditis: "Most common early manifestation," affecting 2.5% of patients.Chronic or constrictive pericarditis: Develops in "10% to 20% of patients 5 to 10 years after radiation therapy." Pericardial calcification is not always present, and late constriction can occur without prior acute pericarditis.Cardiomyopathy: Radiation damages microvasculature, leading to "endothelial dysfunction and ischemia that result in myocardial fibrosis, diastolic dysfunction, and restrictive physiology." Differentiating it from pericardial constriction is crucial for treatment.Valvular Disease: Affects all valves, predominantly left-sided. "Valvular regurgitation due to tissue retraction is the most common valvular lesion in the first two decades after therapy," evolving to "mixed regurgitation and stenosis" with later fibrosis and calcification.Conduction Defects: Common in long-term survivors, including "atrioventricular block, bundle branch block." Increased need for permanent pacing after valve replacement surgery in irradiated patients.Coronary Artery Disease (CAD): Occurs "earlier and with increased incidence." Lesions are typically "ostial, long, smooth, and concentric and have higher fibrotic content than typical atherosclerotic lesions." Traditional risk factors (smoking, dyslipidemia, hypertension) exacerbate incidence, requiring aggressive management.Surgical Outcomes: Surgical outcomes for radiation-associated cardiovascular disease are "significantly worse than in matched cohorts." Percutaneous approaches, such as percutaneous aortic valve replacement, "may be preferable" for aortic stenosis in this group.Surveillance and Prevention:No consensus on cardiac testing in asymptomatic patients, but "baseline evaluation including echocardiography is reasonable."Some organizations recommend "stress echocardiography at 5 to 10 years after completion of therapy or at age 30 years, whichever comes first."Serum biomarkers, nuclear medicine testing, and coronary CT are "not recommended" for routine screening.Statins, ACE inhibitors, and aldosterone antagonists have "not been proved to prevent radiation-induced cardiovascular disease," despite their role in risk factor reduction.II. Cardiotoxicity of ChemotherapyGeneral Principles: Chemotherapy can cause "reversible or dose-dependent, irreversible cardiac injury" (Table 43). Strategies to minimize risk include optimizing traditional risk factors and identifying high-risk patients (Table 44) before treatment.Key Cardiotoxic Agents and Effects (Table 43 & associated text):Left Ventricular Dysfunction (LVD):Anthracyclines (Doxorubicin, Epirubicin, Idarubicin):Acute toxicity: Rare (<1%), reversible, presenting as heart block, arrhythmias, heart failure, myocarditis, or pericarditis.Chronic progressive toxicity: Typically irreversible, presenting as dilated cardiomyopathy. "Most closely linked with doxorubicin."Onset: Early (within 1 year) in 1.6% to 2.1%; late (after 1 year) in up to 5%.Dose-dependent: "Late-onset chronic progressive toxicity is related to total cumulative dose." Incidence of heart failure up to 26% at 550 mg/m2 doxorubicin, with clinical evidence appearing "10 to 20 years after treatment."Mitigation strategies: Dexrazoxane (iron chelator) for high-risk patients; continuous infusion vs. bolus; liposomal formulations of doxorubicin. ACE inhibitors, ARBs, and beta-blockers have not been proven to prevent toxicity.Trastuzumab: Causes "LV systolic dysfunction, with symptoms of heart failure in 3% to 7% of patients." More common in patients older than 50 and with concomitant anthracycline use. Toxicity often reversible.Other Agents: Alkylating agents (cyclophosphamide, ifosfamide), antimicrotubular agents (paclitaxel, docetaxel), proteasome inhibitors (bortezomib, carfilzomib), tyrosine kinase inhibitors (sunitinib).Ischemia: Antimetabolites (5-fluorouracil, capecitabine), antimicrotubular ...
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