Which organ is affected in airline pilot who complained of precordial pain radiating in shoulder?

Diagnosis was Stable angina (angina pectoris)

Stable angina is chest pain or discomfort that most often occurs with activity or emotional stress. Angina is due to poor blood flow through the blood vessels in heart.

Diagnosis can be made from presenting symptoms of the pilot.

Stable angina usually causes uncomfortable pressure, fullness, squeezing or pain in the center of the chest. People feel the discomfort in the neck, jaw, shoulder, back or arm. It is clear that the patient had stable angina also called angina pectoris since he had experience same symptoms i.e severe, intense, precordial, crushing sensation with pain radiating to the left shoulder and down the inside of the left arm, triggered by an off-duty tennis match.

From documented evidence, the time angina pectoris occur can be key in diagnosis process
Occurs during physical activity or strong emotions when the heart muscle itself needs more blood than it is getting. Normally the pain is relieved by rest since the oxygen demand is reduced. This because at rest the narrowed arteries may allow enough blood to reach the heart when the demand for oxygen is low, such as when you are resting. But, when you engage in a physical activity like for this case playing  tennis, the heart works harder to maintain oxygen.Hence pain occurs due to ischemia.

All this symptoms and scenarios were experienced by the pilot, a clear indication that he had stable angina and the fact that the symptoms of pain were relieved by rest confirms the diagnosis.

Treatment of Angina Pectoris

People with angina pectoris require adequate rest and nitroglycerin to relieve the pain. Nitroglycerin relaxes the coronary arteries and other blood vessels, reducing the amount of blood that returns to the heart and easing the heart's workload. By relaxing the coronary arteries, it increases the heart's blood supply.