In your line, the phrase "heart broke" and "anguish" both contain instances of alliteration, but they are not very strong examples since "broke" and "anguish" do not share the same initial consonant sound.
For a clearer example of alliteration, you could look for lines where consecutive words start with the same consonant sounds. For example, a line like "Whispering winds wove wild tales" showcases strong alliteration with the repetition of the 'w' sound.
If you're looking for stronger examples of alliteration from your original line, you might consider revising it to incorporate more repeated consonant sounds.