Table 3.

Frequency of right to left shunt in the three groups of patients with visual aura and the number of patent foramen ovale that were closed versus controls

	Group A MH + aura	Group B MH + aura (unrelated)	Group C aura only	Controls
Patients per group (n)	175	29	21	200
Positive for R to L shunt (n)	168 (96%) (P < 0.0001)*	21 (72%) (P < 0.0001)*	14 (67%) (P < 0.0001)*	36 (18%)
R to L shunts that were closed (n)	67 (40%)	8 (38%)	5 (36%)	0 (0%)

Note:

^*P value comparing each group versus controls.

Abbreviations: MH, migraine headache; R to L, right to left.