Hyperventilation-echocardiography test for the diagnosis of myocardial ischaemia at rest

The purpose of this study was to assess the feasibility, safety, specificity and sensitivity of the hyperventilation test performed under echocardiographic monitoring for the provocation of vasospastic ischaemia. Hyperventilation (approximately 30 cycles.min-1 for 5 min) was performed in 104 hospitalized patients, referred for pain typical of angina at rest, under 2-D echocardiographic and 12-lead electrocardiographic monitoring. All the tests were completed and no significant side effect was observed. In-hospital documentation of spontaneous myocardial ischaemia and/or ergonovine-induced ischaemia was achieved in 38 patients (group I). A positive hyperventilation-echocardiography test (occurrence of new transient asynergies or worsening of basal ones) was obtained in 32/38 patients. Among the group I patients, only 23 had diagnostic ST-T changes and only 16 experienced chest pain during the hyperventilation-echo test. Of the 66 patients without evidence of myocardial ischaemia at rest (negative ECG monitoring during hospitalization and/or negative ergonovine maleate-echo test)--Group II, none showed echocardiographic changes, seven presented ST-T changes and six complained of typical chest pain during the test. Thus, in relation to in-hospital documentation of myocardial ischaemia at rest, both spontaneous and/or ergonovine-induced episodes, the hyperventilation-echo test showed a specificity of 100%, a sensitivity of 84%, a positive predictive value of 100% and a negative predictive value of 92%. In conclusion, hyperventilation performed under echocardiographic monitoring is feasible and safe; it can be proposed as a screening test to unmask vasospastic myocardial ischaemia in patients with angina at rest, in whom documentation of spontaneous episodes is not available.