April 1, 1990

Dissociation of end systole from end ejection in patients with long-term mitral regurgitation.

Q: What is the clinical evidence from this study?

Study design: Observational. Population: Long-term mitral regurgitation (n=59). Intervention: Long-term mitral regurgitation vs. Control patients with atypical chest pain and patients with aortic regurgitation. Primary outcome: Temporal relation between end systole (Tmax) and end ejection (minimum ventricular volume and zero systolic flow) (p=<0.01).

Key Result

Long-term mitral regurgitation is associated with dissociation of end ejection from end systole, with Tmax occurring earlier (266 ms) than minimum ventricular volume (355 ms, p<0.001).

Study Design

Type

Observational (n=59)

Structured PICO

Population

59 patients, including 16 with mitral regurgitation, 21 with aortic regurgitation, and 22 controls, evaluated for left ventricular end systole and end ejection dynamics.

Exposure

Hemodynamic and imaging assessment using micromanometer left ventricular catheters and radionuclide angiograms.

Comparator

Control patients with atypical chest pain and patients with aortic regurgitation.

Outcome

Temporal relation between left ventricular end systole (Tmax) and end ejection (minimum ventricular volume and zero systolic flow).surrogate

In patients with long-term mitral regurgitation, end ejection dissociates from end systole, suggesting that pressure-volume relations calculated at minimum ventricular volume may not accurately reflect left ventricular chamber performance.

Main Result

p-value: p=<0.01

Abstract

To determine whether left ventricular (LV) end systole and end ejection uncouple in patients with long-term mitral regurgitation, 59 patients (22 control patients with atypical chest pain, 21 patients with aortic regurgitation, and 16 patients with mitral regurgitation) were studied with micromanometer LV catheters and radionuclide angiograms. End systole was defined as the time of occurrence (Tmax) of the maximum time-varying elastance (Emax), and end ejection was defined as the time of occurrence of minimum ventricular volume (minV) and zero systolic flow as approximated by the aortic dicrotic notch (Aodi). The temporal relation between end systole and end ejection in the control patients was Tmax (331 +/- 42 SD msec), minV (336 +/- 36 msec), and then, zero systolic flow (355 +/- 23 msec). This temporal relation was maintained in the patients with aortic regurgitation. In contrast, in the patients with mitral regurgitation, the temporal relation was Tmax (266 +/- 49 msec), zero systolic flow (310 +/- 37 msec, p less than 0.01 vs. Tmax), and then, minV (355 +/- 37 msec, p less than 0.001 vs. Tmax and p less than 0.01 vs. Aodi). Additionally, the average Tmax occurred earlier in the patients with mitral regurgitation than in the control patients and patients with aortic regurgitation (p less than 0.01, for both), whereas the average time to minimum ventricular volume was similar in all three patient groups. Moreover, the average time to zero systolic flow also occurred earlier in the patients with mitral regurgitation than in the control patients (p less than 0.01) and patients with aortic regurgitation (p less than 0.05). Because of the dissociation of end systole from minimum ventricular volume in the patients with mitral regurgitation, the end-ejection pressure-volume relations calculated at minimum ventricular volume did not correlate (r = -0.09), whereas those calculated at zero systolic flow did correlate (r = 0.88) with the Emax slope values. We conclude that end ejection, defined as minimum ventricular volume, dissociates from end systole in patients with mitral regurgitation because of the shortened time to LV end systole in association with preservation of the time to LV end ejection due to the low impedance to ejection presented by the left atrium. Therefore, pressure-volume relations calculated at minimum ventricular volume might not be useful for assessing LV chamber performance in some patients with mitral regurgitation.