Effects of exercise on the duration of diastole and on interventricular phase differences in patients with hypertrophic cardiomyopathy: relationship to cardiac output reserve.
BACKGROUND
Our study sought to characterize the effect of exercise on the duration of left ventricular (LV) diastole and interventricular dyssynchrony in patients with hypertrophic cardiomyopathy (HCM). We hypothesized that an abnormally shortened diastolic time may adversely affect cardiac performance.


METHODS
We studied 49 symptomatic patients with HCM during incremental exercise. Twenty-nine patients had obstructive disease (HOCM) and 20 no resting or provocable gradient (HNCM). Right heart catheterization and high temporal resolution radionuclide angiography were simultaneously performed. The loss of diastolic time per beat (LDT(RR)) was quantified using a regression equation obtained from a healthy control group (n = 30).


RESULTS
During rest and peak exercise, a significant shortening of the relative duration of LV diastole (35.6 +/- 5 vs. 38.0 +/- 3 s/min and 29.3 +/- 6 vs. 32.4 +/- 3 s/min; P < or = .02) and an increased interventricular phase delay were evident in patients with HOCM compared to controls. Baseline and peak exercise LDT(RR) values were inversely related to cardiac output reserve and exercise duration. In multivariate analysis, LDT(RR) at peak exercise was identified as an independent predictor of cardiac output reserve.


CONCLUSIONS
In HOCM, baseline abnormalities of the relative duration of LV systolic and diastolic time aggravate during exercise. The disproportionate shortening of diastolic time may significantly impair cardiac efficiency by restricting diastolic filling.
Plehn
Gunnar
G
Department of Cardiology and Angiology, Marienhospital Herne, University of Bochum, Hölkeskampring 40, 44625, Herne, Germany. gunnar.plehn@ruhr-uni-bochum.de
Vormbrock
Julia
J
Meissner
Axel
A
Trappe
Hans-Joachim
HJ
D002312:Cardiomyopathy, Hypertrophic / Q000175:diagnosis* / Q000503:physiopathology*; D003971:Diastole; D005080:Exercise Test; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D006801:Humans; D008297:Male; D008875:Middle Aged; D005082:Physical Exertion; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000503:physiopathology*