Hypertensive Heart Disease: This condition is a common cause of left ventricular hypertrophy, which can lead to left bundle branch block (LBBB) and left axis deviation. The first-degree heart block can also be seen in the context of hypertensive heart disease due to the potential involvement of the conduction system. The patient's symptoms of lightheadedness could be related to decreased cardiac output or arrhythmias associated with hypertensive heart disease.

Atherosclerotic Heart Disease: Coronary artery disease can lead to ischemia or infarction of the conduction system, resulting in LBBB, left axis deviation, and first-degree heart block. Lightheadedness could be a symptom of ischemia or reduced cardiac output.
Cardiomyopathy (Dilated or Hypertrophic): Both dilated and hypertrophic cardiomyopathies can cause LBBB and left axis deviation due to the involvement of the left ventricle. First-degree heart block can also occur, especially in the context of hypertrophic cardiomyopathy affecting the conduction system. Lightheadedness could be due to arrhythmias, outflow tract obstruction, or decreased cardiac output.
Valvular Heart Disease: Conditions like aortic stenosis can lead to left ventricular hypertrophy, potentially causing LBBB and left axis deviation. Mitral valve disease can also lead to similar ECG changes due to the effects on the left ventricle. First-degree heart block can occur due to the involvement of the conduction system. Lightheadedness could be related to decreased cardiac output or arrhythmias.

Acute Myocardial Infarction: Although less common, an acute myocardial infarction, especially involving the anterior wall, can cause LBBB and should be considered urgently due to its high mortality if not promptly treated. First-degree heart block can also occur in the setting of an MI.
Cardiac Sarcoidosis: This condition can infiltrate the heart, including the conduction system, leading to various degrees of heart block, including first-degree, and can cause LBBB. Left axis deviation can also be seen. Lightheadedness could be due to arrhythmias or decreased cardiac output.
Lyme Carditis: A cause of first-degree heart block and can also lead to LBBB, although less common. It's essential to consider in endemic areas or with appropriate exposure history.

Lev Disease: A rare condition characterized by idiopathic fibrosis and calcification of the cardiac conduction system, leading to various degrees of heart block, including first-degree, and can cause LBBB.
Lenegre Disease: Similar to Lev disease, it involves degenerative changes in the conduction system but typically presents at an older age.
Myotonic Dystrophy: A genetic disorder that can affect the heart, leading to conduction abnormalities, including first-degree heart block and potentially LBBB. Left axis deviation can also be seen. Lightheadedness could be related to arrhythmias or muscle weakness.