Exercise left ventricular performance in patients with mitral valve prolapse

Patients with mitral valve prolapse may, even in the absence of associated coronary artery disease or significant mitral regurgitation, have abnormality in exercise left ventricular function. The precise reason for this abnormality, which appears to be age and sex related, is not clear. Abnormal ejection fraction response to exercise cannot be predicted by the nature of symptoms, electrocardiographic changes, arrhythmias, or by extent and severity of mitral valve prolapse by echocardiography. Caution should therefore be exercised in diagnosing associated coronary artery disease based on the ejection fraction response to exercise per se or even on exercise-induced wall motion abnormality. Patients with prolapse, have reduced exercise tolerance, which has been ascribed to reduced left ventricular filling and smaller left ventricular end-diastolic volume in the upright position. Patients with mitral valve prolapse and associated coronary artery disease or significant mitral regurgitation often have, as expected, abnormal left ventricular function during exercise.     

Mitral regurgitation determined by radionuclide cardiography: dependence on posture and exercise.

OBJECTIVES--To evaluate dependence of posture and exercise on the degree of mitral regurgitation using combined first pass and equilibrium radionuclide cardiography. DESIGN--24 patients with clinically stable chronic mitral regurgitation and sinus rhythm were studied by first pass list mode and simultaneous multigated frame mode equilibrium radionuclide cardiography using red cells labelled with technetium-99m. RESULTS--When patients changed posture from supine to sitting upright, left ventricular volumes decreased considerably. Regurgitation tended to increase in patients with valve prolapse but decreased in patients with ischaemic heart disease and dilated cardiomyopathy. During submaximal bicycle exercise cardiac output increased without dilatation of the left ventricle. The increase in left ventricular forward stroke volume was more pronounced than that in the total stroke volume, leading to a considerable decrease in the regurgitant flow through the mitral valve. The repeatability and observer variability of radionuclide determination of regurgitation was acceptable, with limits of agreement within about 10%. CONCLUSIONS--Change in posture induces a normal haemodynamic response in most patients with chronic mitral regurgitation; the effect of posture on regurgitation depends on the underlying disease. Mild to moderate exercise causes no deterioration in the severity of regurgitation.     

Left ventricular function in mitral valve prolapse: Assessment with radionuclide cineangiography

Abnormalities of left ventricular contraction in patients with mitral valve prolapse have suggested a myocardial factor in this disease. To determine systolic left ventricular function in mitral valve prolapse, technetium-99m gated equilibrium radionuclide cineangiography was performed in 47 patients with this diagnosis. In 39 patients without mitral regurgitation the average ejection fraction was normal at rest (average [± standard error of the mean] 57 ± 3 percent, normal 57 ± 1 percent, difference not significant) and exceeded the lower limits of normal in all but 1 patient, whose ejection fraction was 41 percent. However, ejection fraction during maximal exercise was lower for the group of patients with mitral prolapse without mitral regurgitation than for normal subjects (average 64 ± 2 percent, normal 71 ± 2 percent, p < 0.005). In eight patients with mitral prolapse and mitral regurgitation, the average ejection fraction was normal at rest but was diminished with exercise in comparison with both normal subjects and patients with mitral valve prolapse without mitral regurgitation. Chest pain, arrhythmia and the pattern or extent of mitral valve prolapse on echocardlography were not independently associated with impaired left ventricular functional reserve. We conclude that, although many patients with mitral valve prolapse have normal left ventricular function, there is a subgroup without mitral regurgitation in whom diminished left ventricular functional reserve is suggestive of a cardiomyopathic process.     

Clinical and exercise echocardiographic findings in patients with mitral valve prolapse

To assess the relationship between left ventricular functional reserve and prognosis in patients with idiopathic mitral valve prolapse, ergometer exercise echocardiography was performed in 10 normal subjects and 30 patients with mitral valve prolapse having either mild, or no mitral regurgitation. These 30 patients with mitral prolapse were followed for 2 to 8 (mean 4.5) years. Increment of % fractional shortening during maximum exercise at the initial study in patients with mitral valve prolapse and normal subjects were 7 +/- 7 and 11 +/- 3%, respectively. Based on increment of % fractional shortening, patients with mitral valve prolapse were divided into 2 groups; Group I: 13 cases with delta% fractional shortening less than 5%, Group II: 17 cases with delta% fractional shortening greater than or equal to 5%. The incidence of cardiac symptoms was higher in Group I than in Group II (85 vs 41%, p less than 0.05). ST-T changes and life-threatening arrhythmias were more frequently observed in Group I. During the follow-up period, M-mode echocardiographic measurements did not vary in Group II, but left ventricular and left atrial dimensions increased significantly (p less than 0.05, p less than 0.01, respectively) and % fractional shortening decreased significantly (p less than 0.01) in Group I without any change in mitral regurgitation severity. Thus, some patients with mitral valve prolapse not having significant mitral regurgitation may develop progressive deterioration of the cardiac function, which may be predicted by exercise echocardiography.     

Noninvasive assessment of myocardial function in young patients with mitral valve prolapse.

To evaluate myocardial function in patients with documented mitral valve prolapse (MVP) 14 patients (six men and eight women with a mean age of 28 +/- 6.3 years) were examined noninvasively. Systolic time intervals were recorded at rest (in the supine and upright position) and after bicycle ergometry (upright position) and were compared with 10 healthy control subjects of similar age. Tracings were coded with random numbers and were evaluated by two blinded investigators. Contractility indices such as pre-ejection period index (PEPc) and ratio pre-ejection period/left ventricular ejection time (PEP/LVET) revealed no significant differences between patients and controls both at rest and after exercise. We conclude that young patients with MVP have no evidence for impaired myocardial function, provided there is no significant mitral incompetence or associated heart disease.     

Hemodynamic effects of nifedipine during upright exercise in stable angina pectoris and either normal or severely impaired left ventricular function

The immediate effects of sublingual nifedipine (20 mg) were evaluated in 18 men with stable, exercise-related angina pectoris and angiographically confirmed coronary artery obstructions, stratified at the time of left ventricular (LV) angiography according to the degree of LV dysfunction supine at rest (Group 1: n = 9, left ventricular end-diastolic pressure [LVEDP] less than 20 mm Hg; Group 2: n = 9, LVEDP greater than 20 mm Hg). At rest, in the upright posture in both groups, nifedipine reduced the systemic vascular resistance (p less than 0.01). The systemic arterial mean (p less than 0.05) and diastolic (p less than 0.01) pressures were reduced despite an increase in the cardiac output (p less than 0.05). Heart rate was increased only in Group 1 (p less than 0.05). Pulmonary artery occluded pressure was unchanged in both groups. During upright bicycle exercise in all patients, compared to control measurements, systemic arterial pressure (p less than 0.01) and vascular resistance (p less than 0.05) were similarly reduced, while exercise cardiac output response and LV filling pressure did not change after nifedipine. Heart rate was increased in Group 1 (p less than 0.05) and decreased in Group 2 (p less than 0.05). Stroke volume during exercise after nifedipine decreased 1 ml/m2 in Group 1 (p greater than 0.05) and increased 2 ml/m2 in Group 2 (p greater than 0.05) compared to control measurements; the between-group difference in the exercise heart rate and stroke volume responses after nifedipine were significant at the 5% level.(ABSTRACT TRUNCATED AT 250 WORDS)     

Alterations in left ventricular volumes and ejection fraction at rest and during exercise in patients with aortic regurgitation

This study was performed (1) to determine the changes in left ventricular volumes during exercise in patients with aortic regurgitation, and (2) to evaluate the importance of these alterations in characterizing left ventricular function in these patients. In 15 normal subjects (Group I) and in 17 patients with aortic regurgitation (Group II), left ventricular end-diastolic volume index, end-systolic volume index, ejection fraction and the ratio of peak systolic blood pressure to end-systolic volume index were measured at rest and during supine exercise. The patients with aortic regurgitation were classified into two groups on the basis of symptoms and chest radiographs: Group IIA, minimal or no symptoms, no cardiomegaly or pulmonary venous congestion; Group IIB, definite symptoms, with cardiomegaly and pulmonary venous congestion. Patients with aortic regurgitation had greater left ventricular end-diastolic and end-systolic volume indexes at rest and during exercise (p <0.05) than did normal subjects. During exercise, left ventricular end-diastolic volume index increased in normal subjects (53 ± 13 ml/m² [mean ± standard deviation] at rest, 67 ± 18 ml/m² during exercise, p <0.01), demonstrated a heterogeneous response in patients in Group IIA and increased in patients in Group IIB (180 ± 96 ml/m² at rest, 209 ± 102 ml/m² during exercise, p <0.05). During exercise, left ventricular end-systolic volume index decreased in normal subjects (18 ± 5 ml/m² at rest, $\text{15}\text{\$}\text{?}\text{6}$ ml/m² with exercise, p <0.01), increased in patients in Group IIB (82 ± 60 ml/m² at rest, 118 ± 93 ml/m² during exercise, p <0.05), and showed a variable response in those in Group IIA. At rest, left ventricular ejection fraction was similar in the three groups, but during exercise it increased in Group I (0.71 ± 0.07 at rest, 0.82 ± 0.07 with exercise, p <0.001), was unchanged in Group IIA and decreased in Group IIB (0.59 ± 0.15 at rest, 0.50 ± 0.16 during exercise, p <0.05). During exercise, there was an inverse relation between changes in left ventricular ejection fraction and endsystolic volume, but no relation between changes in end-diastolic volume and ejection fraction. Changes in the systolic pressure-volume ratio provided no more information than changes in end-systolic volume alone. Thus, abnormal alterations in left ventricular volumes occur during exercise in patients with aortic regurgitation and may be helpful in the further characterization of left ventricular performance in these patients.     

Effects of upright and supine position on cardiac rest and exercise response in aortic regurgitation

The effects of upright and supine position on cardiac response to exercise were assessed by radionuclide ventriculography in 15 patients with moderate to severe aortic regurgitation (AR) and in 10 control subjects. In patients with AR, heart rate was higher during upright exercise, but systolic and diastolic blood pressure and left ventricular (LV) output were similar during both forms of exercise. LV stroke volume and end-diastolic volume were not altered during supine exercise. LV end-systolic volume increased and ejection fraction decreased during supine exercise, but both were unchanged during upright exercise. Of 15 patients, 5 in the upright and 12 in the supine position had an abnormal LV ejection fraction response to exercise (p less than 0.01). Right ventricular ejection fraction increased and regurgitant index decreased with both forms of exercise and was not significantly different between the 2 positions. Thus, posture is important in determining LV response to exercise in patients with moderate to severe AR.     

Left ventricular function in chronic aortic regurgitation

Left ventricular performance was determined in 42 patients with moderate or severe aortic regurgitation during upright exercise by measuring left ventricular ejection fraction and volume with radionuclide ventriculography. Classification of the patients according to exercise tolerance showed that patients with normal exercise tolerance (greater than or equal to 7.0 minutes) had a significantly higher ejection fraction at rest (probability [p] = 0.02) and during exercise (p = 0.0002), higher cardiac index at exercise (p = 0.0008) and lower exercise end-systolic volume (p = 0.01) than did patients with limited exercise tolerance. Similar significant differences were noted in younger patients compared with older patients in ejection fraction at rest and exercise (both p = 0.001) and cardiac index at rest (p = 0.03) and exercise (p = 0.0005). The end-diastolic volume decreased during exercise in 60% of the patients. The patients with a decrease in volume were significantly younger and had better exercise tolerance and a larger end-diastolic volume at rest than did patients who showed an increase in volume. The mean corrected left ventricular end-diastolic radius/wall thickness ratio was significantly greater in patients with abnormal than in those with normal exercise reserve (mean +/- standard deviation 476 +/- 146 versus 377 +/- 92 mm Hg, p less than 0.05). Thus, in patients with chronic aortic regurgitation: 1) left ventricular systolic function during exercise was related to age, exercise tolerance and corrected left ventricular end-diastolic radius/wall thickness ratio, and 2) the end-diastolic volume decreased during exercise, especially in younger patients and patients with normal exercise tolerance or a large volume at rest.     

Possibilities of stress-echocardiography in diagnostics of pathology of mitral valve. Part II

The paper deals with different aspects of application of stress-echocardiography for assessment of mitral valve disease (acquired stenosis or insufficiency, mitral regurgitation due to ischemic heart disease and mitral valve prolapse). Continuity equation is preferable to pressure half-time and resistance for estimation of hemodynamic significance of mitral stenosis. In some patients studies at rest reveal only slight mitral regurgitation while during stress it becomes hemodynamically significant and associated with pronounced elevation of pulmonary artery pressure. Deterioration of left ventricular function in this pathology often occurs before appearance of symptoms and even before increase of left ventricular dimensions and lowering of ejection fraction can be registered by echocardiography at rest. In patients with mitral valve prolapse stress induced mitral regurgitation has high predictive power for unfavorable clinical course. It is necessary to remember that in this group of patients abnormalities of left ventricular function during stress can be found in the absence of ischemic heart disease or pronounced regurgitation.     

Rest and exercise hemodynamics in pulmonary stenosis: comparison of children and adults

To better understand the hemodynamics of pulmonary stenosis (PS), 24 adults and 53 children with similar degrees of PS who had undergone cardiac catheterization at rest and during supine exercise were retrospectively studied. Three groups were defined. Group I consisted of 9 adults and 18 children with a pulmonary valve area of less than 0.5 cm2/m2; group II, 6 adults and 25 children with a pulmonary valve area of 0.5 to 1.0 cm2/m2; and group III, 9 adults and 10 children with pulmonary valve area of more than 1.0 cm2/m2. The mean ages of the adults were 29, 26 and 22 years for groups I, II, and III, respectively. The mean ages of the children were 11, 10 and 9 years for groups I, II and III, respectively. The pertinent data collected from catheterization included oxygen consumption, cardiac rate and index, arterial venous oxygen difference, stroke index, right ventricular (RV) systolic pressure and RV end-diastolic pressure. Adults and children in groups II and III had an appropriate response to exercise. Group I children responded abnormally by increasing their RV end-diastolic pressure and decreasing their stroke index. In group I adults both of these variables increased. Group I adults exhibited a significantly lower cardiac index at rest and exercise secondary to a significantly lower absolute cardiac rate. Long-standing severe PS results in hemodynamic compromise. Hence, early relief of PS is recommended.     

Left ventricular end-diastolic pressure response to atrial pacing in idiopathic mitral valve prolapse

The response of several parameters of left ventricular function to right atrial pacing was compared in 21 patients with idiopathic mitral valve prolapse and 10 normal patients. An inability to appropriately lower left ventricular end-diastolic pressure with increasing rates was demonstrated in the mitral valve prolapse group. This abnormality was not related to mitral regurgitation or factors other than ventricular performance per se.     

Exercise first-pass radionuclide assessment of left and right ventricular function and valvular regurgitation in symptomatic mitral valve prolapse

The changes in right ventricular (RV) and left ventricular (LV) function and in regurgitant fractions on first-pass exercise radionuclide angiography (RNA) were assessed in 29 consecutive patients with symptomatic mitral valve prolapse (MVP). The mean right ventricular ejection fraction (RVEF) was 35 +/- 8% at rest and 46 +/- 15% after exercise (p less than 0.001). The mean left ventricular ejection fraction (LVEF) was 62 +/- 11% at rest and 74 +/- 13% after exercise (p less than 0.001). Seven of 29 patients had an abnormal RV response and 6 had an abnormal LV response. Eight had abnormal wall motion after exercise. A total of 12/29 patients (41%) had one or more abnormalities. The mean left-sided regurgitant fraction before exercise was 27 +/- 17% in 21/29 patients (72%) and 31 +/- 21% after exercise (p = ns). An additional 5 patients (17%) developed left-sided regurgitation after exercise. These findings indicate that wall motion abnormalities and abnormal RVEF and LVEF responses to exercise occur in symptomatic MVP patients. In addition, 26/29 (89.6%) had left-sided regurgitation after exercise. Since the presence of a murmur did not correlate with the presence of mitral regurgitation by RNA, then symptomatic patients with MVP should have first-pass exercise RNA to assess the presence of regurgitation at rest and after exercise. Antibiotic prophylaxis is recommended in MVP patients with systolic murmurs or with regurgitation. Since patients without murmurs can have regurgitation, further study is necessary to determine the need for endocarditis prophylaxis in these patients.     

Rapid changes in left ventricular dimensions and mass in response to physical conditioning and deconditioning

To assess left ventricular function and to compare mean pulmonary wedge pressure and left ventricular end-diastolic pressure in the supine and sitting positions, 10 patients without demonstrable cardiovascular disease underwent hemodynamic studies at rest and during exercise In the two positions. At rest the values for heart rate were higher and the values for cardiac index, stroke index, left ventricular stroke work Index, mean pulmonary capillary wedge pressure and left ventricular end-diastolic pressure were lower in the sitting position. During both supine and sitting exercise left ventricular end-diastolic pressure, cardiac index, stroke index and left ventricular stroke work index increased significantly from the resting values. Comparison of data during exercise revealed higher values for heart rate and rate-pressure product and lower values for pulmonary capillary wedge pressure, left ventricular end-dlastollc pressure and stroke index in the sitting position; systolic and mean systemic pressure, cardiac index and left ventricular stroke work Index were similar during the two exercise periods. When absolute changes from rest to exercise were compared, the Increase In heart rate, systolic blood pressure, pulmonary capillary wedge pressure, left ventricular end-dlastollc pressure, cardiac index, stroke index, and left ventricular stroke work index were similar In the two positions. There was a good correlation between left ventricular end-diastolic pressure and pulmonary capillary wedge pressure at rest and during exercise in the two postures.     

Haemodynamic adaptation at rest and during exercise to long-term antihypertensive treatment with combination of beta-receptor blocking and vasodilator agent.

Systemic and pulmonary haemodynamics were studied at rest in the supine and upright position, and during exercise in the sitting position at 75 and 150 Watt, in 13 hypertensive men aged 50-8 +/- 8-7 years before and after 13 months treatment with oral oxprenolol (120 to 160 mg t.i.d.) supplemented by oral hydrallazine (50 to 75 mg t.i.d.) during the last 6 months. Pressures were recorded by means of catheters inserted percutaneously into the pulmonary and brachial artery; cardiac output was determined according to Fick. Treatment resulted in a significant reduction of systemic systolic, diastolic, and mean pressures at rest in the supine position and during exercise, and of systolic pressures in the upright posture. Pulmonary systolic and mean pressures increased slightly at rest in the supine position and during exercise, and no changes occurred at rest in the upright position. The left ventricular filling pressure was unchanged at rest both in the supine and upright position; it increased slightly during exercise. The haemodynamic changes by which systemic pressure was reduced were those typical of beta-adrenergic blockade: reduction of cardiac output resulting from a decrease of both heart rate and stroke volume, while the total systemic vascular resistance was unchanged at rest in the supine position but increased in the upright posture and during exercise. The A-V O2 difference increased remarkably. This long-term observation again suggests that the acute haemodynamic effects of an antihypertensive regimen can be modified during long-term application. It did not give evidence of a readjustment of the vascular resistance occurring, at least not in the upright position and during exercise, as has been suggested for long-term beta-adrenergic blockade.     

Ejection fraction response to supine exercise in asymptomatic aortic regurgitation: relation to simultaneous hemodynamic measurements

The change in ejection fraction during exercise is frequently employed as a measure of left ventricular functional reserve in patients with aortic regurgitation. However, little information is available about its relation to invasive measurements of cardiac performance. Therefore, simultaneous hemodynamic measurements and supine exercise blood pool scintigraphy were performed in 14 patients with severe, asymptomatic or minimally symptomatic aortic regurgitation associated with cardiomegaly but preserved left ventricular function at rest. Their hemodynamic measurements at rest were normal and their exercise capacity was excellent. When the patients were categorized into those patients whose ejection fraction increased or did not decrease by more than 0.05 (Group 1) and those whose ejection fraction decreased by more than 0.05 (Group 2), important differences were apparent. Echocardiographic, radionuclide and hemodynamic measurements at rest in the two patient groups were similar, but Group 1 exhibited a greater increase in cardiac index during supine exercise (2.8 +/- 0.4 to 10.0 +/- 1.8 versus 2.7 +/- 0.5 to 6.9 +/- 1.0 liters/min per m2; p less than 0.005) and a lesser increase in pulmonary capillary wedge pressure (13 +/- 4 to 19 +/- 7 versus 12 +/- 4 to 31 +/- 8 mm Hg; p less than 0.01). The severity of regurgitation decreased during exercise in all patients, but end-diastolic volume decreased and end-systolic volume decreased or was unchanged in Group 1, whereas end-diastolic volume was unchanged and end-systolic volume increased in Group 2.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mechanisms for decreased exercise capacity after bed rest in normal middle-aged men

The mechanisms responsible for the decrease in exercise capacity after bed rest were assessed in 12 apparently healthy men aged 50 +/- 4 years who underwent equilibrium gated blood pool scintigraphy during supine and upright multistage bicycle ergometry before and after 10 days of bed rest. After bed rest, echocardiographically measured supine resting left ventricular end-diastolic volume decreased by 16% (p less than 0.05). Peak oxygen uptake during supine effort after bed rest was diminished by 6% (p = not significant [NS]), whereas peak oxygen uptake during upright effort declined by 15% (p less than 0.05). After bed rest, increases in heart rate were also greater during exercise in the upright than in the supine position (p less than 0.05). Values of left ventricular ejection fraction increased normally during both supine and upright effort after bed rest and were higher than corresponding values before bed rest (p less than 0.05). After bed rest, increased left ventricular ejection fraction and heart rate largely compensated for the reduced cardiac volume during supine effort, but these mechanisms were insufficient to maintain oxygen transport capacity at levels during upright effort before bed rest. These results indicate that orthostatically induced cardiac underfilling, not physical deconditioning or left ventricular dysfunction, is the major cause of reduced effort tolerance after 10 days of bed rest in normal middle-aged men.     

Effects of oral hydralazine on rest and exercise hemodynamics in patients with aortic or mitral regurgitation and left ventricular dysfunction

The hemodynamic effects of afterload reduction were studied at rest and during two levels of upright exercise in patients with aortic or mitral regurgitation and left ventricular dysfunction. Eleven patients underwent invasive hemodynamic monitoring before and after 50–70 mg of oral hydralazine was given every 6 h for 48 h. At rest, heart rate and mean arterial pressure after hydralazine were unchanged from control. During exercise, there was no significant change in heart rate, but mean arterial pressure fell significantly during the first level of exercise. Systemic vascular resistance was elevated before hydralazine and was significantly reduced after treatment at both exercise levels. After hydralazine, the resting oxygen consumption was significantly elevated at rest but was unchanged during exercise, the arteriovenous oxygen difference was significantly narrowed at both rest and exercise, and the pulmonary capillary wedge pressure was also significantly lower at both rest and exercise. In this select group of patients who are not candidates for surgical valve replacement, chronic afterload reduction with oral hydralazine may result in increased cardiac performance, decreased pulmonary congestion, reduced myocardial oxygen demands, and improvement in resting and/or exertional symptoms.     

Differing mechanisms of exercise flow augmentation at the mitral and aortic valves

To determine the mechanisms by which blood flow increases across the mitral and aortic valves during exercise, 18 normal men were studied during graded supine and upright bicycle exercise at matched workloads. Mitral valve orifice and ascending aortic blood velocities were recorded by Doppler echocardiography during steady states at each stage of exercise. Parasternal two-dimensional echocardiographic imaging of the ascending aorta adjacent to the aortic valve orifice and the mitral valve orifice at the tips of the valve leaflets was used to calculate changes in cross-sectional area during exercise. Heart rate increased from rest to exercise from 67 to 150 beats/min (124%) during supine exercise and from 72 to 147 beats/min (104%) during upright exercise. Stroke volume increased 20% during supine and 46% during upright exercise; the increase in stroke volume was statistically significant when rest and exercise were compared and when the magnitude of change was compared vs position (p less than .05). The increase in stroke volume measured at the ascending aorta was accomplished by an increase in the velocity-time integral (+15% supine and +48% upright, p less than .05), with little change in aortic cross-sectional area (5% supine and 0% upright, p = NS). By contrast, the increase in flow rate measured at the mitral valve was predominantly due to an increase in mean diastolic cross-sectional area (+29% supine and 34% upright, p less than .05); the velocity-time integral did not increase significantly (-10% supine and 4% upright; p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)     

Age- and gender-related changes in exercise left ventricular function in mitral valve prolapse

The correlates of exercise left ventricular (LV) performance were examined in 45 patients with isolated mitral valve prolapse (no associated mitral regurgitation or coronary artery disease). There were 18 men and 27 women, aged 16 to 73 years; 20 patients were 40 years or younger and 25 were older than 40. The response of the LV ejection fraction (EF) to symptom-limited upright exercise was normal (at least a 5% increase) in 27 patients (60%) and abnormal in 18 (40%). There were no significant differences between patients with normal and abnormal EF response in clinical presentation, electrocardiographic findings (at rest or during exercise), medications, rest EF, heart rate (at rest or during exercise) and systemic arterial pressure (at rest and during exercise). A normal EF response was observed more frequently in patients 40 years or younger than in those older than 40 (80 vs 44%, p less than 0.01), and more often in men than in women (78 vs 48%, p less than 0.04). The change in EF from rest to exercise was 18 +/- 9% in men and 5 +/- 10% in women 40 years or younger (p less than 0.01), and 9 +/- 8% in men and 2 +/- 8% in women older than 40 (p less than 0.04). Thus, patients (especially women and those older than 40 years) with isolated mitral valve prolapse may have abnormal LV functional reserve. Genetic differences in the expression of the disease in both sexes and age-related irreversible myocardial changes may explain these observations.