Comparison of the hemodynamics and volume and output changes at rest and during exercise were analyzed using a paired f-test. Univariate correlations were performed for the exercise-induced changes in forward and regurgitant flows.
The resting and exercise data of our patients are shown in Table 1. All patients had normal sinus rhythm and a resting left ventricular ejection fraction >0.55. Only one patient (No 6) has a regurgitant fraction <50 percent (46 percent). In general, these patients exercised to a reasonable workload (mean 664 ± 273 kg-m/ min). Three patients, however, achieved peak workloads less than 600 kg-m/min (200, 300, and 400 kg-m/min, respectively). Only one patient (No 5) developed regional wall motion abnormalities with exercise, consisting of only mild hypokinesis in the inferoapical area. In this patient, the EF dropped from 0.71 at rest to 0.63 with exercise, but the RF also dropped from 53 percent at rest to 39 percent with exercise. Three additional patients had significant falls (>.05) in EF with exercise, but none had regional wall motion abnormalities. The exercise EF dropped below 0.50 in only one patient (No 2), from 0.59 at rest to 0.48 with exercise; in this patient, the RF also dropped from 62 percent at rest to 57 percent during peak exercise.
The exercise changes in the ejection fraction and the regurgitant fraction were quite variable (Table 1 and Fig 1), but there were no significant changes between the exercise and resting values. There was no significant correlation between the exercise EF and the exercise RF (r=0.49; p = 0.17) or between the exercise-induced changes in EF and RF (r = 0.06; p = 0.86). In addition, neither the exercise changes in EF nor RF correlated with the exercise change in systolic pressure.
The effects of exercise on hemodynamics and changes in left ventricle volumes and forward and regurgitant outputs are shown in lable 1 and Figure 2. There were no significant exercise changes in end-diastolic volume index, end-systolic volume index, ejection fraction, or regurgitant fraction in these patients. At peak exercise, the total stroke volume index decreased by 8 percent (p<0.05), but the total cardiac index increased significantly by 72 percent (p<0.01) due to an 87 percent increase (p<0.01) in the heart rate. The forward cardiac index also increased significantly by 86 percent (p<0.01) with no significant change in the forward SVI. There was a significant correlation between the exercise change in heart rate and the change in cardiac index (r = 0.86; p<0.01) and the change in forward cardiac index (r=0.70; p<0.02). Although the regurgitant SVI declined slightly by 12 percent at peak exercise (p = 0.07), the total regurgitant flow increased markedly by 64 percent (p<0.01), to an average of 8.2 L/min/m2. There was no significant correlation between exercise change in regurgitant flow and change in heart rate (r = 0.33; p = 0.33) or systolic blood pressure (r=0.08; p = 0.81).
Table I—Effects of Exercise on Hemodynamic and Left Ventricular Volumes and Output Changes m Patients with Severe Mitral Regurgitation
|Patient||Heart Rate||SBP||ED VI||ESVI||EF||RF||Stroke Volume Index||Cardiac Index|
Figure 1. Distribution of changes in resting and exercise ejection fractions (left panel) and regurgitation fractions (right panel) in patients with severe mitral regurgitation.
Figure 2. Exercise changes by percentages in patients with severe mitral regurgitation (abbreviations are as used in the text).