Radiation Induced Coronary Artery Disease

The classic presentation of RICAD is typical chest pain in a young patient that has been formerly exposed to thoracic RT and has no risk factors for CAD. [15] Patients can also present in pulmonary edema, acute heart failure, or valvular disease with a new heart murmur. There may be decades between initial exposure to RT and symptoms of RICAD. Women and the elderly commonly present with atypical chest pain. The two most distinguishing characteristics that separate RICAD from acute coronary syndrome (ACS) is the age at presentation and history of RT. As with the history, the physical exam findings found in RICAD patients can be very similar to ACS. Hypertension and tachycardia may be present. The classic Levine sign, a clenched hand held over the chest, can also be seen in these patients as with ACS. Patients with RICAD may have dyspnea, lower extremity edema, bi-basilar pulmonary crackles, and jugular venous distension. Even with a history and physical, it can be challenging to identify the etiology of chest pain as RT can affect all exposed thoracic tissues resulting in irritation and/or inflammation, including the pericardium, lung parenchyma, pleura, esophagus, and other structures of the chest.

Evaluation is similar to that for ACS. For patients with chest pain, obtain an electrocardiogram, troponin, B-type natriuretic peptide (BNP), D-dimer, and echocardiogram.  If there is a low risk for obstructive CAD, consider a cardiac stress test. If high risk, coronary angiography is indicated. [7] Of note, RICAD affects the region of radiation exposure. Right-sided radiation exposure mainly affects the right coronary artery, whereas left-sided exposure mostly affects the left main and anterior descending artery. 

Treatment of RICAD is similar to ACS, which includes pharmacotherapy, percutaneous coronary intervention (PCI), and surgical revascularization. In animal models, captopril [16] and simvastatin [17] decreased the effects of a radiation-induced injury. There is also evidence to support colchicine as prophylactic therapy for RICAD. [18] In addition to treating RICAD, it is important to include regular surveillance for radiation-induced injury to the heart and other mediastinal structures. [7] Annual evaluations and risk factor modification are recommended. Laboratory tests to be monitored include troponin, BNP, and C-reactive protein. The American Society of Echocardiography and European Association of Cardiovascular Imaging recommend a pre-radiation echocardiogram and a repeat in 10 years followed by 5-year intervals. [19]

The differential for RICAD is similar to the differential list for ACS, as both present the same. A list of potential but not all-inclusive differential diagnosis are listed below:

• Acute coronary syndrome
• Acute pericarditis
• Pulmonary embolism
• Coronary vasospasm
• Cardiac syndrome X
• Pulmonary disease
• Costochondritis
• Kawasaki disease
• Myocarditis
• Esophagitis

RICAD has a good prognosis with current medical therapy.

Complications of RICAD are similar to CAD including:

• Myocardial ischemia/infarction
• Dysrhythmia
• Valvular disease
• Aortic disease
• Aortic dissection
• Heart failure
• Sudden cardiac death

It is recommended that cardiology be consulted.

Patient education starts with the initial discussion prior to the initiation of RT. After informed discussion, patients should be allowed the option to defer RT. Other options for treatment should be offered. Sources of natural radiation exposure may also be discussed.

The workup and diagnosis of RICAD are identical to that for CAD and ACS. [7]

RICAD may be overlooked as a potential diagnosis. An interprofessional team approach can sometimes aid in narrowing the diagnosis. Members should include but are not limited to the primary care provider, cardiologist, oncologist, cardiology nurse, and pharmacist. Emergency room providers and nurses may be involved in the initial assessment and treatment. Critical care and cardiology nurses provide treatments, monitor outcomes, and document status for the team. The pharmacist reviews medication choice, check for interactions and provide patient education. [Level 5]