What is the significance of a nondiagnostic Electrocardiogram (ECG) portion of a Lexiscan (regadenoson) stress test, with a normal myocardial perfusion study and normal Left Ventricular (LV) systolic function with a Left Ventricular Ejection Fraction (LVEF) of 56%?

From the Guidelines

The results of your Lexiscan stress test are reassuring and indicate a healthy heart, with no evidence of significant coronary artery disease that would require immediate medical intervention or changes to your current treatment plan. Your ECG portion was nondiagnostic, which means it didn't provide clear information about heart function during stress, but this is not uncommon [ 1 ]. More importantly, your myocardial perfusion study was normal, showing no evidence of reduced blood flow (ischemia) or heart muscle damage (infarct). Your left ventricular ejection fraction (LVEF) is 56%, which falls within the normal range (typically 50-70%), indicating that your heart is pumping blood effectively [ 1 ]. Your left ventricular systolic function and wall motion are also normal, meaning your heart muscle is contracting properly.

Some key points to consider based on your test results include:

• The annualized event rate for patients with a normal pharmacologic stress perfusion result is about 1.6%, which is relatively low [ 1 ].
• Patients with a normal study result have a significantly lower risk for cardiovascular death or MI compared to those with severely abnormal results [ 1 ].
• Stress echocardiography with dobutamine can also accurately classify patients into high- and low-risk categories, with a normal dobutamine echocardiogram associated with a risk for an adverse cardiac event of 1% to 2% [ 1 ].

Given these findings, no specific medication changes or additional testing are needed based on these results. However, it's still important to continue any heart-healthy practices like regular exercise, maintaining a healthy diet, and taking any prescribed medications for other conditions you may have [ 1 ]. Additionally, it's essential to recognize that when relatively extensive ischemia is detected by stress imaging (≥10%), there is no evidence that early revascularization improves prognosis even in patients with diabetes or ventricular dysfunction [ 1 ].

Overall, your test results suggest that you don't have significant coronary artery disease that is limiting blood flow to your heart muscle, and you can continue with your current treatment plan and heart-healthy lifestyle [ 1 ].

From the Research

Nondiagnostic ECG and Normal Myocardial Perfusion Study

• A nondiagnostic ECG portion of a Lexiscan stress test, combined with a normal myocardial perfusion study showing no evidence of myocardial ischemia or infarct, may not necessarily rule out the presence of coronary artery disease 2.
• The study by 2 highlights the case of a 63-year-old female with multiple cardiovascular risk factors who presented with a nontypical chest pain syndrome, and whose myocardial perfusion imaging with a regadenoson (Lexiscan) Technetium Tc99 m (Sestamibi) stress test was interpreted as normal, but was later found to have significant coronary artery disease.

Normal LV Systolic Function and Wall Motion

• A normal LV systolic function and wall motion with an LVEF of 56% is a good prognostic sign, but does not exclude the possibility of coronary artery disease or myocardial ischemia 3.
• The study by 3 discusses the management of chronic coronary artery disease and the role of stress-induced myocardial ischemia in identifying patients who may benefit from revascularization.

Regadenoson Stress Testing

• Regadenoson is a pharmacological stress agent that has been widely used for stress testing, and has been shown to be safe and effective in most patients with chronic diseases 4.
• However, the use of regadenoson has not been studied in patients of low socioeconomic class, and there are equivocal results in the literature for other chronic diseases 4.

Myocardial Ischemia and Coronary Artery Disease

• Myocardial ischemia is characterized by an imbalance between myocardial oxygen supply and demand, causing cardiac dysfunction, arrhythmias, myocardial infarction, and sudden death 5.
• The study by 5 discusses the current concepts and future perspectives of myocardial ischemia, and highlights the importance of endothelial regulation and the Rho-kinase pathway in the pathogenesis of coronary artery disease.