**Introduction / Hypothesis**
Introduction:
Treatment with β-Blockers is usually well tolerated; thus, side effects can often remain unrecognized and could possibly lead to unnecessary medical interventions.

**Methods**
Case:
A 75-year-old male with history of hypertension and hyperlipidemia presented with abdominal pain. Computed tomography of the abdomen and pelvis showed a Stanford Type B aortic dissection distal to the subclavian extending through the abdominal aorta into the left common and upper iliac artery. Transthoracic echocardiogram (TTE) at that time showed normal left ventricular function and trivial tricuspid regurgitation (TR). Vascular surgery evaluated the patient and opted for conservative management with metoprolol tartrate and antihypertensive agents.
Incidentally found were also multiple liver lesions and a left adrenal mass. Liver biopsy showed well-differentiated grade 2 neuroendocrine tumor with likely origin at the left adrenal gland. Positron emission tomography scan showed evidence of metastatic disease with avid foci in the liver, lymph nodes, bone, pancreatic head and left adrenal gland. Urine serotonin and chromogranin A testing were both elevated.
Over the next three months, the patient developed severe progressive fatigue for which a repeat TTE was obtained showing incomplete closure of the tricuspid valve (TV) with new severe wide-open TR, trace pulmonary valve regurgitation, and right ventricular enlargement. Bubble study showed only trivial right-to-left shunt. TTE findings were suspicious for cardiac carcinoid at which time treatment with octreotide was initiated. Cardiovascular surgery recommended TV replacement; however, the procedure was considered very high risk given comorbidities.
Unfortunately, the patient continued to endorse progressive fatigue, dyspnea on exertion and peripheral edema. Repeat TTE obtained two months after the last one, showed a severely thickened TV with retracted leaflets and incomplete TV coaptation resulting in severe TR with hepatic vein reversal, moderate pulmonary valve regurgitation, and moderately enlarged right ventricle with mildly reduced systolic function. At that time, transcatheter edge-to-edge repair (TEER) of the tricuspid valve for management of symptoms was considered. However, upon further review, the patient was advised to first trial metoprolol dose reduction and transitioning from metoprolol tartrate to metoprolol succinate which resulted in significant improvement of his symptoms over one month. Ultimately, a decision was made to postpone valve replacement given comorbidities and near complete resolution of symptoms with medication adjustments.

**Results**
Decision making:
Initial symptomatic presentation and evidence of cardiac carcinoid syndrome leading to significant valvular disease prompted a decision for TV replacement. However, fatigue and dyspnea on exertion were also recognized to be well-documented side effects on patients undergoing treatment with metoprolol due to alterations in cardiac function and hemodynamics. Additionally, a direct correlation of incidence of side effects and dosage has been reported. Ultimately, metoprolol dose adjustments and initiation of Lasix were proved to be sufficient in the treatment of this patient.

**Conclusion**
Conclusion:
Recognition of side effects secondary to treatment with metoprolol was paramount for the diagnosis and treatment of this patient. Thus, it is important to maximize medical management prior to considering advanced interventions such as tricuspid valve TEER or replacement.



Blocked by Tunnel Vision - A Case of Medication Optimization