Background: Mechanisms behind exercise-induced increase of mitral regurgitation (MR) in patients with chronic ischemic heart disease have been described earlier. We describe the determinants of exercise-induced changes in MR in patients with non-ST-elevation acute coronary syndrome (NSTACS).
Methods: Forty-five consecutive patients (mean + or - SD age 64 + or - 10 years, 37 men) with NSTACS underwent exercise echocardiography on a supine bicycle the day before angiography. The exercise was started with a load of 10 W with increments of 10 W every minute until symptoms developed or a max load of 100 W. Effective regurgitation orifice (ERO) was measured at rest and at peak exercise.
Results: Twelve patients had more than trace MR at rest with ERO 8 + or - 5 (mean + or - SD), range: 3-18 mm(2). In these patients, ERO increased during exercise to 13 + or - 6 (mean + or - SD), range: 6-23 mm(2) corresponding to an increase of 70% from rest (P = 0.001). Seven other patients developed new MR during exercise with ERO at peak exercise of 8 + or - 4 mm(2) (mean + or - SD), range: 4-14 mm(2). All these patients had significant increase in wall motion score index (WMSI) of 0.14 + or - 0.18 (mean + or - SD), P = 0.006, while in the 25 patients without MR at rest or during exercise, WMSI remained unchanged, -0.02 + or - 0.08 (mean + or - SD), P = 0.2.
Conclusion: Exercise-induced increases of MR in patients with NSTACS are related to worsening of regional wall motions. (Echocardiography 2010;27:567-574).