If a feeling of arm heaviness were caused by a heart attack, would it occur in both arms, or just the left?

Radiating Heart Pain: Pain related to heart attack can be felt on both shoulders and upper arms, or to lesser extent the right shoulder and arm, not just the left side only.

Angina : Approx 40% sufferers experience " atypical" symptoms : the location & distribution of radiating symptoms is insufficiently consistent to alone allow precise diagnosis ;a detailed consultation is needed