Muscle loss can be quantified with advanced imaging studies but this is not frequently pursued. Treatment depends on the underlying cause but will often include exercise and adequate nutrition. Anabolic agents may have some efficacy but are not often used due to side effects. There are multiple treatments and supplements under investigation but there are currently limited treatment options in clinical practice. Given the implications of muscle atrophy and limited treatment options, minimizing immobility is critical in injury or illness. Signs and symptoms
The hallmark sign of muscle atrophy is loss of lean muscle mass. This change may be difficult to detect due to obesity, changes in fat mass or edema. Changes in weight, limb or waist circumference are not reliable indicators of muscle mass changes.The predominant symptom is increased weakness which may result in difficulty or inability in performing physical tasks depending on what muscles are affected. Atrophy of the core or leg muscles may cause difficulty standing from a seated position, walking or climbing stairs and can cause increased falls. Atrophy of the throat muscles may cause difficulty swallowing and diaphragm atrophy can cause difficulty breathing. Muscle atrophy can be asymptomatic and may go undetected until a significant amount of muscle is lost. Causes
Skeletal muscle serves as a storage site for amino acids that can be used for energy production when demands are high or supplies are low. If metabolic demands remain greater than protein synthesis, muscle mass is lost.
This delayed activation also results in a widening of the QRS complex, although not to the extent of a complete LBBB. Diagnosis
Abnormal left axis deviation (usually between –45° and –60°)
qR pattern (small q, tall R) in the lateral limb leads I and aVL
rS pattern (small r, deep S) in the inferior leads II, III, and aVF
Delayed intrinsicoid deflection in lead aVL (> 0.045 s)LAFB cannot be diagnosed when a prior inferior wall myocardial infarction (IMI) is evident on the ECG. IMI can also cause extreme left-axis deviation, but will manifest with Q-waves in the inferior leads II, III, and aVF. By contrast, QRS complexes in the inferior leads should begin with r-waves in LAFB. Effects of LAFB on Diagnosing Infarctions and Left Ventricular Hypertrophy
LAHB may be a cause of poor R wave progression across the precordium causing a pseudoinfarction pattern mimicking an anteroseptal infarction. It also makes the electrocardiographic diagnosis of LVH more complicated, because both may cause a large R wave in lead aVL. Therefore, to call LVH on an EKG in the setting of an LAHB you should see the presence of a “strain pattern” when you are relying on limb lead criteria to diagnose LVH

Clinical significance
It can be seen in approximately 4% of cases of acute myocardial infarctionIt is the most common type of intraventricular conduction defect seen in acute anterior myocardial infarction, and the left anterior descending artery is usually the culprit vessel. It can be seen with acute inferior wall myocardial infarction.