Effect of atrial fibrillation on exercise capacity in mitral stenosis

Left Atrial Appendage Function Analyzed by Tissue Doppler Imaging in Mitral Stenosis: Effect of Afterload Reduction after Mitral Valve Commissurotomy

BACKGROUND

This study sought to investigate the relative load dependence of left atrial appendage (LAA) tissue Doppler velocities in patients with mitral stenosis after percutaneous mechanical mitral commissurotomy (PMMC).

METHODS

LAA tissue Doppler velocities were obtained in 34 patients with mitral stenosis (20 with sinus rhythm and 14 with atrial fibrillation) before and after PMMC by transesophageal echocardiography. Standard ultrasound studies were also performed for mitral valve orifice area, transmitral pressure gradient, and LAA blood flow velocity measurements.

RESULTS

PMMC resulted in a significant increase in mitral valve area (P < .001) and decrease in mean transmitral pressure gradient (P < .001). LAA tissue Doppler velocities consisted of a triphasic velocity profile: SLAA and ELAA occurring during left ventricular contraction and relaxation, respectively, and ALAA occurring after the atrial contraction. After PMMC, ELAA and ALAA velocities consistently increased (4.8 +/- 1.2 to 7.9 +/- 2.6 cm/sec [P < .001] and 6.6 +/- 2.9 to 8.1 +/- 4.2 cm/sec [P < .05], respectively). The mean transmitral pressure gradient was significantly correlated with ALAA before and after PMMC (r = .65).

CONCLUSIONS

In mitral stenosis, tissue Doppler velocities illustrated improvement of regional LA function after PMMC, in relation to decreased transmitral pressure gradient.

Mechanism of improvement in exercise capacity after the maze procedure combined with mitral valve surgery

OBJECTIVE

To clarify the mechanism of improvement in exercise capacity after the maze procedure.

DESIGN

Retrospective study.

SETTING

Tertiary referral centre.

PATIENTS

26 patients (mean (SD) age 57 (9) years) with atrial fibrillation (AF) and mitral valve disease were studied with echocardiography and cardiopulmonary exercise testing before and after the maze procedure combined with mitral valve surgery. Of these, eight had persistent AF and 18 had restored sinus rhythm (SR) by the surgery. Six patients (mean (SD) age 59 (12) years) with AF undergoing mitral valve surgery without the maze procedure who had cardiopulmonary exercise testing before and after the surgery formed the control group.

MAIN OUTCOME MEASURES

Echocardiographic parameters of atrial function were measured from transmitral flow recordings. Peak oxygen uptake (VO2) and the slope of the relation between VO2 and workload (ratio of DeltaVO2 to Delta work) were determined as indices of exercise capacity.

RESULTS

The degree of improvements in peak VO2 and the ratio of DeltaVO2 to Delta work after the mitral valve surgery was comparable between the maze and control group. It was also comparable between patients with and those without successfully restored SR after the maze procedure. The degree of the increase in peak VO2 correlated with the change in left atrial diameter (r = -0.40, p = 0.047) but atrial contraction did not correlate with the increase.

CONCLUSIONS

Improvement in exercise capacity may not be caused by restored SR and atrial contraction but may at least partly relate to the reduction of left atrial size and improvement of haemodynamic variables by the surgery.

Effect of mitral valve surgery on exercise capacity, ventricular ejection fraction and neurohormonal activation in patients with severe mitral regurgitation

OBJECTIVES

The purpose of this study was to prospectively investigate the effects of surgical correction of mitral regurgitation (MR) on exercise performance, cardiac function and neurohormonal activation.

BACKGROUND

Little is known about the effect of surgical correction of MR on functional status or on neurohormonal activation.

METHODS

Cardiopulmonary exercise test, radionuclide angiography and blood samples for assessment of neurohormonal status were obtained in 40 patients with nonischemic MR before and within one year (216+/-80 days) after surgery. Twenty-four patients underwent mitral valve repair (MVr), and 16 underwent valve replacement (VR) with anterior chordal transection.

RESULTS

Despite an improvement in New York Heart Association functional class, exercise performance did not change (peak oxygen consumption: 19.3+/-6.1 to 18.5+/-5.6 ml/kg/min, percentage of maximal predicted oxygen consumption: 79.5+/-18.2% to 76.8+/-16.9%). After surgery, left ventricular (LV) ejection fraction (EF) decreased (64.2+/-10.3% to 59.9+/-11.4%, p = 0.003) while right ventricular (RV) EF increased (41.4+/-9.6% to 44.7+/-9.5%, p = 0.03). Left ventricular EF did not change after MVr (64.3+/-11.5% to 61.5+/-12.2%), but RVEF improved (40.4+/-9.2% to 46.0+/-10.0%, p = 0.02). In contrast, VR was associated with an impairment of LV function in the apicolateral area and a decrease in LVEF (64.1+/-8.5% to 57.4+/-10.0%, p = 0.01), whereas RVEF did not change (42.9+/-10.3% to 42.8+/-8.6%). Moreover, there was only a slight decrease in neurohormonal activation after surgery.

CONCLUSIONS

Despite an improvement in symptomatic status, exercise performance was not improved seven months after either MVr or VR for MR, and neurohormonal activation persisted. Compared with MVr, VR resulted in a significant impairment of cardiac function in this study.

Exercise performance and training in cardiac patients with atrial fibrillation

PURPOSE

Exercise training in cardiac patients with chronic atrial fibrillation (AF) has received little attention in the literature. Therefore, this study compared exercise performance and the effect of an exercise training program over a period of 3 months in patients with and without AF.

METHODS

Data in patients with AF (n = 19) were compared with a control group of patients in sinus rhythm (n = 44), drawn from a database of 2,116 patients. Patients performed a maximal exercise test on the bicycle until exhaustion before and after an ambulatory exercise training program where exercise training was offered 3 times a week for 3 months.

RESULTS

Before training, peak oxygen uptake (VO2) was significantly lower in patients with AF compared with the control group (1271 +/- 368 versus 1496 +/- 414 mL/min, P < 0.05). Exercise training significantly increased peak VO2 in both groups (+31%, P < 0.001 in AF and +25%, P < 0.001 in the control group). The gain in peak VO2 did not significantly differ between both groups. A significant decrease in resting heart rate was achieved in both groups after exercise training. AF was also a significant and independent determinant of peak VO2 in the total database, but not of the change in peak VO2.

CONCLUSIONS

Exercise training significantly improves exercise performance in cardiac patients with AF. AF affects exercise performance but does not impair the beneficial effects of training. Patients with chronic AF should therefore not be dissuaded from participating in exercise training after a cardiac event.

Outcome of atrial fibrillation after mitral valve repair

OBJECTIVE

The aim of the study was to evaluate the prognostic factors for return to sinus rhythm after mitral valve repair.

METHOD

One hundred ninety-one patients underwent surgery for mitral valve repair, including 142 procedures for valve repair only (74%). The patients with preoperative atrial fibrillation (50.5%) were older, clinically more symptomatic, and had a greater degree of left atrial dilation than the patients who had sinus rhythm.

RESULTS

Preoperative cardiac rhythm, the duration of preoperative atrial fibrillation, and a lesser degree of left atrial hypertrophy are significant prognostic factors independent of the maintenance of sinus rhythm. The probability of return to stable sinus rhythm was 93.7% when sinus rhythm was already present before the operation and 80% when atrial fibrillation was intermittent or of less than 1 year's duration; probability declined abruptly for durations over 1 year. No significant difference in patient survival was noted between those who had sinus rhythm (99% +/- 0.9% at 1 year and 86% +/- 6.6% at 5 years) and those who had atrial fibrillation in the preoperative period (95% +/- 3.1% at 1 year and 86% +/- 8.4% at 5 years). In contrast, the postoperative return to sinus rhythm was associated with 99% +/- 0.9% and 94% +/- 4.8% survivals at 1 and 4 years versus 97% +/- 1.5% and 77% +/- 13% in the event of postoperative atrial fibrillation.

CONCLUSION

The aim of restoring postoperative sinus rhythm after mitral valve repair should lead to surgery being conducted on patients who have sinus rhythm or recent-onset atrial fibrillation. Surgery for atrial fibrillation may be of value in patients with a long history of atrial fibrillation, providing that it does not induce prohibitive excess mortality.