Abstract 1720: Paradoxical Angina Pectoris: Occurrence of Myocardial Ischemic Attack With Paradoxically Increasing Coronary Blood Supply Through Non-obstructive Coronary Artery
Background: Ischemic heart disease (IHD) in women remains a clinical challenge, because diverse mechanisms are involved in the pathogenesis. By acetylcholine provocation test (ACh-test), we can identify coronary spasm and examine abnormal vasoreactivity in microvessels by measuring coronary blood flow volume (CBFV). Recently, we found special women’s sub-group presenting myocardial ischemia induced by ACh with paradoxical increase in CBFV.
Methods and Results: In 138 consecutive women complaining chest pain without obstructive IHD, we performed ACh-test and measured CBFV using Doppler FloWire. Simultaneously, transcardiac lactic acid production (TLAP) was evaluated by blood sampling from aortic root and coronary sinus to assess myocardial ischemia. ACh successfully increased CBFV in 42 women; 29 patients did not exhibit any ischemic findings (control), but we could specifically identify 13 women (9.4%) showed chest oppression and ischemic changes in electrocardiogram with positive TLAP (post ACh; + 23 ± 31%, p < 0.01) as “paradoxical angina pectoris (paradoxical AP)”. At baseline, coronary flow average peak velocity (APV) was significantly higher and diastolic to systolic velocity ratio (DSVR) was significantly lower in patients with paradoxical AP than control (APV; 24 ± 6 vs. 19 ± 5cm/sec, p < 0.01, DSVR; 1.6 ± 0.3 vs. 2.1 ± 0.6 p < 0.05). By ACh-test, CBFV increase was comparable in two groups (CBFV; 183 ± 37 vs. 229 ± 109% p = 0.19). After intra-coronary administration of isosorbide dinitrate, transcardiac lactic acid extraction ratio was significantly lower in paradoxical AP patients than control (6.8 ± 9.1 vs. 18.8 ± 9.3%; p = 0.04). Coronary flow reserve assessed by ATP infusion was not significantly different (2.8 ± 0.7 vs. 3.3 ± 0.8; p = 0.09). We treated the paradoxical AP patients with calcium-channel blockers, nitrates, and β-blockers. During 39 months follow-up, two re-admissions for refractory angina were documented.
Conclusion: We first identified the specific IHD sub-population of NOCAD (10%) in women with paradoxically increasing CBFV, using our original diagnostic criteria. Paradoxical AP might be caused by novel abnormality of coronary microcirculation, leading to unfavorable outcome and effective treatments should be determined.