Residency · Residency · Cardiology

Cardio-Oncology

Cancer Therapy-Related Cardiac Dysfunction (CTRCD)

Definition and Classification (2022 ESC Guidelines)

The 2022 ESC guidelines on cardio-oncology established a standardized classification system for cancer therapy-related cardiac dysfunction. Symptomatic CTRCD is defined as the development of new heart failure symptoms at NYHA Class II through IV with an accompanying decline in left ventricular ejection fraction. Asymptomatic CTRCD is graded by severity: severe when the ejection fraction falls below 40%, moderate when it is 40 to 49% with a new decline of 10% or more from baseline, and mild when the ejection fraction remains at 50% or above but has declined by 10% or more from baseline, or when global longitudinal strain has declined by more than 15% relative to baseline values. Recovery is defined as ejection fraction returning to within 5% of the pre-treatment baseline, while partial recovery indicates improvement of 10% or more but remaining more than 5% below baseline.

Anthracycline Cardiotoxicity

Anthracycline cardiotoxicity represents the prototypical Type I cancer therapy-related cardiac dysfunction, characterized by direct and potentially irreversible cardiomyocyte damage. The molecular mechanisms involve topoisomerase IIbeta inhibition, generation of reactive oxygen species, mitochondrial dysfunction, and DNA damage. The relationship between cumulative dose and heart failure risk is well established: cumulative doxorubicin exposure exceeding 400 mg/m squared is associated with a 5% heart failure incidence, while doses exceeding 550 mg/m squared carry a 26% incidence. It is crucial to recognize, however, that cardiotoxicity can occur at any cumulative dose.

Risk factors for anthracycline cardiotoxicity include cumulative dose, age extremes below 5 or above 65 years, prior mediastinal radiation, preexisting cardiac disease, concurrent trastuzumab administration, female sex, renal dysfunction, and African American race. Prevention strategies encompass cumulative dose limitation, use of liposomal formulations that provide reduced cardiotoxicity with equivalent anticancer efficacy, and dexrazoxane, an iron chelator that reduces reactive oxygen species generation and is recommended when cumulative doxorubicin reaches 300 mg/m squared. Slower infusion rates of 60 minutes or longer also reduce cardiotoxic risk. Monitoring requires baseline echocardiography with global longitudinal strain assessment before chemotherapy initiation, repeated at cumulative dose milestones of 200, 300, and 400 mg/m squared or every 2 to 3 cycles, with troponin measurement at each treatment cycle for early detection of subclinical injury.

HER2-Targeted Therapy Cardiotoxicity

Trastuzumab and pertuzumab cause Type II cardiotoxicity that is generally reversible upon drug discontinuation. The ErbB2/HER2 signaling pathway is essential for cardiomyocyte survival, and its inhibition impairs the cardiac stress response. Left ventricular ejection fraction decline occurs in 7 to 28% of patients, with higher rates when concurrent anthracyclines are administered, and overt heart failure develops in 3 to 7%. Unlike anthracycline toxicity, this form is not dose-dependent and cumulative exposure is not a risk factor.

Monitoring requires ejection fraction assessment every 3 months during treatment, with global longitudinal strain providing earlier detection of subclinical dysfunction. When ejection fraction drops by more than 10% to below 50%, trastuzumab should be held and cardiomyopathy treatment with angiotensin-converting enzyme inhibitors and beta-blockers initiated. Reassessment at 3 to 4 weeks determines whether treatment can resume, with permanent discontinuation required if the ejection fraction remains persistently below 40% or the patient develops symptomatic heart failure.

Immune Checkpoint Inhibitor (ICI) Myocarditis

Immune checkpoint inhibitor myocarditis represents one of the most feared complications in modern oncology. Agents implicated include anti-PD-1 antibodies such as nivolumab and pembrolizumab, anti-PD-L1 antibodies such as atezolizumab and durvalumab, and anti-CTLA-4 antibodies such as ipilimumab. The incidence is estimated at 1 to 2%, though this is likely underreported. Combination immunotherapy, particularly anti-PD-1 plus anti-CTLA-4, carries the highest risk. The presentation is frequently fulminant, with rapid hemodynamic decline, high-grade atrioventricular block, ventricular tachycardia or fibrillation, and a mortality rate of 25 to 50% in fulminant cases. Onset typically occurs within the first 3 months of therapy, with a median of 34 days, often after only 1 to 2 doses. Concurrent skeletal muscle involvement with elevated creatine kinase occurs in approximately 25% of cases, with some patients developing concurrent myasthenia gravis symptoms.

Diagnosis relies on elevated troponin, which is the most sensitive marker, new electrocardiographic changes, echocardiography showing new wall motion abnormalities or reduced ejection fraction, and cardiac magnetic resonance imaging demonstrating edema and late gadolinium enhancement. Endomyocardial biopsy showing lymphocytic infiltration may be required when diagnostic uncertainty persists. Management requires permanent discontinuation of the immune checkpoint inhibitor, followed by high-dose methylprednisolone at 1 gram intravenously daily for 3 to 5 days. Refractory cases may require addition of mycophenolate mofetil, tacrolimus, or anti-thymocyte globulin. Abatacept, a CTLA-4 agonist, and ruxolitinib, a JAK inhibitor, are emerging as targeted therapeutic options. Mechanical circulatory support is deployed for cardiogenic shock.

VEGF Inhibitor Cardiotoxicity

Vascular endothelial growth factor inhibitors, including bevacizumab, sunitinib, sorafenib, pazopanib, axitinib, cabozantinib, and lenvatinib, produce cardiovascular toxicity through several mechanisms. Hypertension is the most common cardiovascular effect, occurring in 20 to 80% of patients through decreased nitric oxide production, increased endothelin-1, and capillary rarefaction. Left ventricular dysfunction occurs in approximately 5 to 15% of patients and is usually reversible. Arterial thrombotic events, including myocardial infarction and stroke, occur in 1 to 4%. QT prolongation is a concern, with vandetanib carrying the highest risk, necessitating electrocardiographic monitoring. Management requires aggressive blood pressure control targeting less than 130/80 mmHg, with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers as preferred agents. The VEGF inhibitor should be held when systolic blood pressure exceeds 180 mmHg or diastolic pressure exceeds 110 mmHg despite treatment.

Cancer Therapy Cardiotoxicity Summary

Other Cardiotoxic Cancer Therapies

Several additional cancer therapies carry significant cardiovascular toxicity. Proteasome inhibitors, particularly carfilzomib, cause heart failure in approximately 5 to 10% and hypertension, with higher rates than bortezomib. Chimeric antigen receptor T-cell therapy can trigger cytokine release syndrome with hypotension, tachycardia, capillary leak, and troponin elevation in approximately 40% of patients, managed with tocilizumab, dexamethasone, and hemodynamic support. Ibrutinib, a BTK inhibitor, causes atrial fibrillation in 5 to 15%, ventricular arrhythmias, and hypertension, sometimes requiring drug discontinuation. MEK inhibitors such as trametinib cause left ventricular dysfunction in approximately 10% of patients, requiring ejection fraction monitoring. The fluoropyrimidines 5-fluorouracil and capecitabine cause coronary vasospasm in 2 to 5% of patients, presenting as chest pain during infusion and treated with calcium channel blockers and nitrates. The offending drug should be discontinued, and rechallenge is not recommended.

<image> A comprehensive surveillance protocol diagram for cardio-oncology monitoring during cancer treatment. Show a timeline from "Pre-Treatment Baseline" extending rightward through treatment cycles and into follow-up. At baseline: "Cardiac history/exam, ECG, Echo with GLS, Troponin, BNP/NT-proBNP, Lipid panel." For Anthracyclines (red timeline): troponin at each cycle (shown as blood drop icons), echo with GLS at cumulative dose milestones (200, 300, 400 mg/m^2, shown as echo probe icons), then annually post-treatment for 5 years, then as clinically indicated. For HER2 therapy (blue timeline): echo with GLS every 3 months during treatment (echo probe icons at Q3 month intervals); continue during adjuvant treatment. For ICI therapy (green timeline): troponin at baseline, with each cycle for first 3-6 months, then PRN; ECG with each cycle. For VEGF inhibitors (orange timeline): BP monitoring at each visit (BP cuff icon), ECG for QT monitoring, echo if symptoms develop. Below the timelines, a decision box: "Actionable findings: GLS decline >15% from baseline → initiate cardioprotection (ACEi + beta-blocker); LVEF decline >10% to <50% → hold cancer therapy + initiate cardiomyopathy treatment; Troponin rise → evaluate for myocarditis, ischemia." Use color coding matching each therapy type. </image>

Radiation-Induced Heart Disease (RIHD)

Pathology

Radiation-induced heart disease develops with a latency of 5 to 20 or more years following thoracic radiation, with risk proportional to cardiac radiation dose. Cardiac doses exceeding 30 Gy are associated with significant risk, though modern radiation techniques including intensity-modulated radiation therapy and proton therapy substantially reduce cardiac exposure. Pericardial disease is the most common early manifestation, presenting as acute pericarditis, chronic pericardial effusion, or constrictive pericarditis developing 10 to 20 years after treatment. Accelerated coronary artery disease with a characteristic ostial and proximal distribution within the radiation field, most commonly affecting the left anterior descending and right coronary arteries, presents 10 to 30 years post-radiation.

Valvular disease results from fibrosis and calcification, with the aortic and mitral valves most commonly affected and significant valvular disease developing in 10 to 15% of patients at 20 years. Cardiomyopathy follows a restrictive pattern driven by myocardial fibrosis, with diastolic dysfunction progressing to heart failure with preserved ejection fraction. Conduction system fibrosis produces atrioventricular block and bundle branch block. A hallmark of radiation-induced heart disease is the common coexistence of multiple pathologies, with pericardial, valvular, and coronary disease frequently occurring together in the same patient.

Screening and Management

Annual cardiovascular assessment is recommended beginning 5 years post-radiation for patients who received high-dose therapy of 30 Gy or greater. Echocardiography and stress testing are performed at the 5-year mark, then every 5 years if asymptomatic, with more frequent evaluation if abnormalities are detected. Coronary artery calcium scoring is useful, with a score above 0 prompting further functional testing or coronary CT angiography. Surgical considerations in this population are complex because radiation vasculopathy, mediastinal fibrosis, and porcelain aorta make cardiac surgery technically challenging and higher risk. Transcatheter aortic valve replacement is preferred over surgical aortic valve replacement for radiation-associated aortic stenosis, and percutaneous approaches are preferred over surgical approaches when feasible.

Cardioprotection Strategies

Pharmacologic Cardioprotection

Several pharmacologic agents have demonstrated cardioprotective effects during cancer therapy. The OVERCOME trial showed that enalapril preserved left ventricular ejection fraction in patients with hematologic malignancies receiving anthracyclines. The PRADA trial demonstrated that candesartan attenuated ejection fraction decline during anthracycline therapy. Among beta-blockers, carvedilol has shown cardioprotective effects in small studies, while the CECCY trial in breast cancer patients demonstrated that carvedilol reduced troponin elevation but not ejection fraction decline. The STOP-CA trial showed that atorvastatin 40 mg during anthracycline therapy provided a small but statistically significant preservation of ejection fraction, attributed to anti-inflammatory and antioxidant mechanisms. Dexrazoxane remains underutilized despite being the only FDA-approved cardioprotective agent during anthracycline therapy. It is approved for patients with metastatic breast cancer who have received 300 mg/m squared or more of doxorubicin, does not reduce anticancer efficacy, and directly reduces reactive oxygen species-mediated cardiomyocyte injury.

Exercise

Aerobic exercise during and after cancer therapy improves cardiorespiratory fitness, reduces cancer-related fatigue, and may attenuate cardiotoxicity. The ACC/AHA recommends 150 minutes per week of moderate-intensity exercise for cancer survivors.

Thrombotic Complications in Cancer

Cancer-Associated Thrombosis

Cancer patients face a 4 to 7-fold higher risk of venous thromboembolism, with the Khorana score available for risk assessment in ambulatory cancer patients. Cancer-associated pulmonary embolism can mimic primary cardiac disease and should be considered in any cancer patient presenting with new dyspnea. For treatment of established venous thromboembolism, direct oral anticoagulants have replaced low-molecular-weight heparin as the first-line approach. The HOKUSAI-VTE Cancer and CARAVAGGIO trials support rivaroxaban, edoxaban, and apixaban in this setting. An important exception is gastrointestinal or genitourinary cancers with mucosal involvement, where direct oral anticoagulants carry higher bleeding risk and low-molecular-weight heparin is preferred. Primary thromboprophylaxis in high-risk ambulatory patients with elevated Khorana scores is supported by apixaban at 2.5 mg twice daily or rivaroxaban at 10 mg daily, as demonstrated in the AVERT and CASSINI trials.

Tumor-Related Cardiac Emergencies

Superior vena cava syndrome from tumor compression or invasion requires stenting for immediate hemodynamic relief, followed by tumor-specific radiation or chemotherapy. Pericardial tamponade from malignant effusion necessitates emergent pericardiocentesis, with pericardial window for recurrence and consideration of intrapericardial chemotherapy. Cardiac metastases arise most commonly from melanoma, which has the highest cardiac tropism among solid tumors, followed by lung cancer, breast cancer, and lymphoma. Among primary cardiac tumors, myxoma is the most common benign tumor, rhabdomyoma is the most common in children, and sarcoma is the most common primary malignant cardiac tumor.

<image> An illustration showing the mechanisms of cardiotoxicity from four major cancer therapy classes. Four quadrants arranged in a 2x2 grid around a central damaged cardiomyocyte. Top left (Anthracyclines, red): show doxorubicin molecule entering the cardiomyocyte, targeting topoisomerase IIb in the nucleus (DNA damage), generating reactive oxygen species (ROS shown as orange stars) in the mitochondria, causing mitochondrial dysfunction and apoptosis. Drug dose icon showing cumulative dose-response. Top right (HER2-Targeted, blue): show trastuzumab antibody binding to HER2 receptor on cell surface, blocking ErbB2 survival signaling (crossed-out downstream pathway: PI3K/Akt), labeled as "reversible, not dose-dependent." Bottom left (ICI, green): show T-cell (activated by ICI) infiltrating the myocardium, attacking cardiomyocytes; PD-1/PD-L1 checkpoint removed, allowing unchecked T-cell cytotoxicity against cardiac tissue; labeled "immune-mediated myocarditis." Bottom right (VEGF Inhibitors, orange): show endothelial cell with blocked VEGF signaling, resulting in: reduced NO production (vasoconstriction/HTN), capillary rarefaction, and platelet activation (arterial thrombosis). Central damaged cardiomyocyte showing: swollen mitochondria, nuclear fragmentation, and calcium overload. Each quadrant labeled with drug examples and clinical manifestations. </image>

Cancer Survivorship and Long-Term CV Care

CV Risk in Cancer Survivors

Cancer survivors face a 2 to 6-fold higher risk of cardiovascular mortality compared to age-matched general population controls. Shared risk factors between cancer and cardiovascular disease, including smoking, obesity, sedentary lifestyle, and metabolic syndrome, are compounded by the direct cardiotoxic effects of cancer treatment. Childhood cancer survivors are at particularly high risk, as demonstrated by the Childhood Cancer Survivor Study, with a cumulative cardiovascular disease incidence of approximately 30% by age 50. Anthracycline and radiation exposure during childhood carry lifelong cardiovascular consequences.

Survivorship CV Assessment

Comprehensive cardiovascular survivorship care includes aggressive assessment and management of traditional cardiovascular risk factors including hypertension, diabetes, dyslipidemia, and smoking. Echocardiography with global longitudinal strain should be performed at baseline post-treatment and periodically based on risk stratification. Exercise stress testing provides functional assessment and coronary artery disease screening in radiation-exposed patients. Cardiac rehabilitation, though underutilized in cancer survivors, improves fitness, quality of life, and potentially reduces cardiovascular events.

Key Clinical Pearls

• GLS is the earliest and most sensitive marker of subclinical anthracycline cardiotoxicity -- a relative decrease > 15% from baseline should trigger cardioprotective therapy (ACEi + beta-blocker) even if LVEF remains normal
• ICI myocarditis has a 25-50% mortality rate in fulminant cases and requires IMMEDIATE discontinuation of immunotherapy and high-dose IV methylprednisolone -- any troponin rise in an ICI patient warrants urgent cardiac evaluation
• Dexrazoxane is underutilized as a cardioprotective agent during anthracycline therapy -- it does not compromise anticancer efficacy and should be considered when cumulative doxorubicin dose approaches 300 mg/m^2
• Radiation-induced heart disease is a multi-component disease (pericardial + valvular + coronary + myocardial) that presents years to decades after treatment -- cancer survivors with prior thoracic radiation need lifelong cardiovascular surveillance
• The decision to continue or discontinue cardiotoxic cancer therapy must be made jointly by oncology and cardiology -- premature cancer therapy cessation for marginal cardiac findings can compromise cancer survival
• DOACs have replaced LMWH as first-line anticoagulation for cancer-associated VTE in most patients, EXCEPT those with GI/GU mucosal tumors (higher bleed risk with DOACs)

References

• Lyon AR, et al. 2022 ESC Guidelines on Cardio-Oncology Developed in Collaboration with the EHA, ESTRO, and ICHOC. Eur Heart J. 2022;43:4229-4361.
• Herrmann J, et al. Evaluation and Management of Patients with Heart Disease and Cancer: AHA Scientific Statement. Circulation. 2022;146:e183-e203.
• Mahmood SS, et al. Myocarditis in Patients Treated with Immune Checkpoint Inhibitors. JACC. 2018;71:1755-1764.
• Armenian SH, et al. Prevention and Monitoring of Cardiac Dysfunction in Survivors of Adult Cancers: AHA Scientific Statement. JACC. 2017;70:2811-2822.
• Cardinale D, et al. Early Detection of Anthracycline Cardiotoxicity and Improvement with Heart Failure Therapy. Circulation. 2015;131:1981-1988.

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