Functional mitral regurgitation at rest determines the acute hemodynamic response to cardiac resynchronization therapy during exercise: an acute exercise echocardiographic study.
BACKGROUND
Cardiac resynchronization therapy (CRT) acutely enhances forward stroke volume (FSV) during exercise by reducing the severity of functional mitral regurgitation (MR) in patients with systolic chronic heart failure. Whether CRT increases FSV in patients without functional MR at rest is unknown. Accordingly, the aim of the study was to compare the effect of CRT on exercise-induced increase in FSV in patients with chronic heart failure with or without functional MR at rest.


RESULTS
Forty-one patients with systolic chronic heart failure who had recently undergone CRT performed 2 exercise stress echocardiography tests, the first with CRT On and the second with CRT Off. Twenty-six patients had more than trivial MR (effective regurgitant orifice [ERO] < 10 mm2 in 16 patients, < 20 mm2 in 8 patients, and > or = 20 mm2 in 2 patients), and 15 patients had no MR at rest. Mean exercise-induced change (Delta) in mitral ERO was reduced by CRT (8 +/- 7 mm2 vs 1 +/- 4 mm2, P < .00001). In patients with functional MR at rest, Delta FSV during dynamic exercise was greater with CRT On than CRT Off (4 +/- 8 vs -2 +/- 7 mL, P = .0002), whereas CRT did not significantly affect Delta FSV in patients without MR at rest (9 +/- 9 mL vs 9 +/- 9 mL, P = .93). Similarly, Delta cardiac output was greater with CRT On than CRT Off (1.6 +/- 1.2 L/min vs 1.1 +/- 1.2 L/min, P = .002) in patients with functional MR at rest, whereas Delta cardiac output was similar with CRT On and CRT Off in patients without MR at rest (1.9 +/- 1.4 L/min vs 2.0 +/- 1.2 L/min, P = .59). Severity of functional MR decreased or failed to increase, whereas cardiac output improved during exercise in 9 of 26 patients (34%) with CRT On and in only 2 of 26 patients (8%) with CRT Off (P = .039).


CONCLUSIONS
Functional MR at rest may be an important determinant of the acute hemodynamic response to CRT during exercise.
Maréchaux
Sylvestre
S
Centre Hospitalier Régional et Universitaire de Lille, Department of Ultrasound and Physiology, Lille, France.
Pinçon
Claire
C
Gal
Benjamin
B
Kouakam
Claude
C
Marquié
Christelle
C
Lacroix
Dominique
D
de Groote
Pascal
P
Mouquet
Frédéric
F
Le Tourneau
Thierry
T
Dennetière
Stéphane
S
Guyomar
Yves
Y
Solal
Alain Cohen
AC
Logeart
Damien
D
Asseman
Philippe
P
Le Jemtel
Thierry H
TH
Ennezat
Pierre Vladimir
PV
D000368:Aged; D002304:Cardiac Pacing, Artificial; D004452:Echocardiography; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000150:complications / Q000000981:diagnostic imaging* / Q000517:prevention & control*; D006801:Humans; D008297:Male; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging* / Q000209:etiology / Q000517:prevention & control*; D015203:Reproducibility of Results; D012146:Rest; D012680:Sensitivity and Specificity