Which of the following is an indication for biventricular pacemaker therapy?

Biventricular pacemaker therapy, also known as cardiac resynchronization therapy (CRT), is indicated primarily for patients who exhibit heart failure symptoms and have significant ventricular dyssynchrony. The criteria for this therapy are well-established in clinical guidelines, particularly focusing on patients with reduced ejection fraction and persistent symptoms.

In this case, the correct indication involves patients who have New York Heart Association (NYHA) functional class II to IV heart failure symptoms and an ejection fraction of 35% or less. This demographic represents individuals who are experiencing moderate to severe heart failure symptoms, which often leads to decreased cardiac output and quality of life. The low ejection fraction indicates significant systolic dysfunction, and biventricular pacing can help improve synchrony between the right and left ventricles, enhancing overall cardiac function and symptom relief.

The other options do not align with the criteria for biventricular pacemaker therapy. For instance, NYHA class I patients typically do not experience symptoms that would warrant intervention like CRT. Age alone, without any functional status or ejection fraction context, does not indicate the need for a biventricular pacemaker. Similarly, intermediate angina symptoms are not specifically related to heart failure management, which is what CRT