Cardiac resynchronisation therapy reduces functional mitral regurgitation during dynamic exercise in patients with chronic heart failure: an acute echocardiographic study

Abstract

Objectives: To assess non-invasively the acute effects of cardiac resynchronisation therapy (CRT) on functional mitral regurgitation (MR) at rest and during dynamic exercise. Methods: 21 patients with left ventricular (LV) systolic dysfunction and functional MR at rest, treated with CRT, were studied. Each patient performed a symptom-limited maximal exercise with continuous two dimensional Doppler echocardiography twice. The first exercise was performed with CRT; the second exercise was performed without CRT. Mitral regurgitant flow volume (RV), effective regurgitant orifice area (ERO) and LV dP/dt were measured at rest and at peak exercise. Results: CRT mildly reduced resting mitral ERO (mean 8 (SEM 2) v 11 (2) mm 2 without CRT, p = 0.02) and RV (13 (3) v 18 (3) ml without CRT, p = 0.03). CRT attenuated the spontaneous increase in mitral ERO and RV during exercise (1 (1) v 9 (2) mm 2 , p = 0.004 and 1 (1) v 8 (2) ml, p = 0.004, respectively). CRT also significantly increased exercise-induced changes in LV dP/dt (140 (46) v 479 (112) mm Hg/s, p , 0.001). Conclusion: Attenuation of functional MR, induced by an increase in LV contractility during dynamic exercise, may contribute to the beneficial clinical outcome of CRT in patients with chronic heart failure and LV asynchrony. P atients with chronic heart failure (CHF) due to left ventricular (LV) systolic dysfunction commonly develop functional mitral regurgitation (MR) at rest.1 Functional MR may worsen when these patients exercise.2 3 Worsening functional MR during exercise may negatively affect the long-term outcome of patients with CHF by further activating neurohormonal systems.Cardiac resynchronisation therapy (CRT) improves clinical outcome in patients with severe CHF.4 5 The present study was undertaken to assess non-invasively the acute effects of CRT on functional MR at rest and during dynamic exercise. PATIENTS AND METHODS Study populationWe screened 39 patients with CHF, functional MR and CRT. Eighteen of these patients were excluded for poor acoustic window (n = 4), sinus or atrioventricular blocks (n = 5), atrial fibrillation (n = 3), wire displacement (n = 2), orthopaedic limitation (n = 2) and improved LV ejection fraction . 45% (n = 2).The study population comprised the remaining 13 men and eight women (mean age 67 (SEM 2) years) with CHF caused by ischaemic (n = 8) or non-ischaemic dilated cardiomyopathy (LV end diastolic diameter 69 (4) mm, LV end diastolic volume 249 (19) ml) and reduced LV ejection fraction (22 (1)%). These 21 patients had undergone CRT for a mean duration of 2.3 (1.3) months. All patients were in sinus rhythm and before pacemaker implantation had a left bundle branch block (mean QRS interval 175 (16) ms). The devices were programmed in the DDDR mode with the shortest programmable atrioventricular delay (mean 135 (4) ms) to ensure full and permanent biventricular capture. This also provided, by Doppler echocardiography, the longest filling time and optimised LV end diastolic flow before onset of systole. 6 The programmable in...

Impact of All-Day Physical Activity on Ventilatory Perfusion Coupling in Patients Undergoing Cardiac Resynchronization Therapy

“…In addition, the respiratory exchange ratio (a measure of exercise intensity) was decreased during single-LV and BiV pacing during the same exercise workload compared to baseline (VVI 30) and RV pacing. Besides the improvement in metabolic parameters and CO, BiV pacing has been demonstrated to result in an improvement in functional mitral regurgitation in heart failure patients, especially under exercise conditions [23,24,25,26]. The present data indicate that the increase in CO as well as the decrease in dynamic mitral regurgitation during CRT augment the pressure gradient across the pulmonary vascular bed.…”

Functional Mitral Regurgitation at Rest Determines the Acute Hemodynamic Response to Cardiac Resynchronization Therapy During Exercise: An Acute Exercise Echocardiographic Study

“…4,5 During exercise, worsening of functional MR tends to decrease forward stroke volume (FSV) in patients with CHF. 6 Conversely, cardiac resynchronization therapy (CRT) acutely increases FSV during exercise by reducing the severity of functional MR. [7][8][9] Whether CRT similarly increases, FSV during exercise in patients without resting functional MR is unclear.…”

Secondary Mitral Regurgitation in Heart Failure with Reduced or Preserved Left Ventricular Ejection Fraction

“…Altogether, a decrease in regurgitant flow is associated with an improved forward stroke volume and thereby end-organ perfusion. Besides increased loading conditions, active myocardial ischemia contributes to worsening secondary MR, while medical and nonpharmacological treatments including revascularization and cardiac resynchronization therapy reduce the amount of MR [19,20,21,22,23,24]. A major feature of secondary MR in HFrEF is its dynamic nature with exercise.…”