Baseline Testing Prior to Cardiology Referral
Before referring a patient to cardiology, order a 12-lead ECG, complete blood count, comprehensive metabolic panel (including electrolytes, renal function, glucose, and liver function tests), lipid profile, thyroid-stimulating hormone, and chest X-ray. 1
Essential Laboratory Tests
The initial laboratory evaluation should include the following tests to identify reversible causes and guide the cardiologist's assessment:
Complete blood count to assess for anemia, which can exacerbate cardiac symptoms and affect prognosis 1
Comprehensive metabolic panel including:
- Serum electrolytes (sodium, potassium, calcium, magnesium) to identify imbalances that may cause arrhythmias or worsen cardiac function 1
- Blood urea nitrogen and creatinine to assess renal function, as kidney disease significantly impacts cardiac medication dosing and prognosis 1
- Fasting blood glucose and glycated hemoglobin (HbA1c) to screen for diabetes, which is a major cardiovascular risk factor 1
- Liver function tests (ALT, AST, alkaline phosphatase, total bilirubin, albumin) to establish baseline hepatic function before initiating cardiac medications 1
Lipid profile (total cholesterol, LDL-C, HDL-C, triglycerides) to assess cardiovascular risk and guide statin therapy 1
Thyroid-stimulating hormone (TSH) because both hyperthyroidism and hypothyroidism can cause or contribute to cardiac dysfunction 1
Urinalysis to screen for proteinuria and other renal abnormalities 1
Essential Cardiac Testing
12-lead electrocardiogram should be performed in all patients, as it provides critical information about rhythm, conduction abnormalities, prior infarction, and ventricular hypertrophy 1, 2
Chest radiograph (PA and lateral views) to assess cardiac silhouette size, pulmonary congestion, and pleural effusions, though note that cardiomegaly may be absent even in chronic heart failure 1, 2
Additional Testing Based on Clinical Context
Consider these additional tests when specific clinical scenarios are present:
BNP or NT-proBNP can help support or exclude heart failure diagnosis, with BNP <35 pg/mL or NT-proBNP <125 pg/mL making chronic heart failure unlikely 1, 2
Troponin (preferably high-sensitivity assay) if acute coronary syndrome is suspected or to rule out myocardial injury 1
Screening for hemochromatosis with fasting transferrin saturation in patients with unexplained cardiomyopathy, particularly those of Northern European descent 1
HIV screening in high-risk patients presenting with new-onset heart failure 1
Critical Pitfalls to Avoid
Do not delay referral waiting for echocardiography results – the cardiologist will typically order this as part of their evaluation, and a normal ECG has >90% negative predictive value for excluding left ventricular systolic dysfunction 2
Do not rely solely on chest X-ray to exclude cardiac disease, as cardiomegaly can be absent on imaging despite significant cardiac dysfunction 2
Do not forget to assess volume status, orthostatic blood pressure changes, weight, height, and body mass index during the physical examination, as these provide important baseline data 1
Do not overlook medication history – specifically document current and past use of alcohol, illicit drugs, chemotherapy agents (especially anthracyclines, trastuzumab, cyclophosphamide), and alternative therapies that may cause cardiotoxicity 1
Documentation for the Cardiologist
Provide the cardiologist with a thorough history including:
- Assessment of the patient's ability to perform routine and desired activities of daily living 1
- Detailed cardiovascular risk factor assessment 1
- Family history of cardiomyopathy, sudden unexplained death, and conduction system disease 1
- Symptoms including onset, duration, type, location, triggers, and relieving factors 1
This systematic approach ensures the cardiologist receives comprehensive baseline data to guide their evaluation and management decisions efficiently.