QT dispersion in patients with mitral valve prolapse is related to the echocardiographic degree of the prolapse and mitral leaflet thickness.

BACKGROUND: Ventricular arrhythmias are common in patients with mitral valve prolapse (MVP). Previous studies have provided evidence that a higher degree of systolic mitral valve displacement and the presence of a thickened anterior mitral leaflet are related to an increased incidence of complex ventricular arrhythmias and risk of sudden death in these patients. The aim of our study was to investigate whether QT dispersion in patients with MVP is associated with the echocardiographic degree of the prolapse and mitral leaflet thickness. METHODS: QT and JT intervals and dispersions were measured in 89 patients with primary mitral valve prolapse (26 men and 63 women with mean age 39 +/- 14 years). All patients underwent a full echocardiographic examination and a scoring system was used to determine the degree of MVP. Anterior mitral leaflet thickness was also measured. Twenty-four hour Holter monitoring was used to assess ventricular arrhythmogenesis. RESULTS: According to their echocardiographic score. patients were divided into three groups (Group A. B and C) reflecting the different degrees of the prolapse. QT dispersion in patients with the highest degree of MVP, i.e. Group C was significantly greater (65 +/- 13 ms) than that of the other two groups (Group A: 38 +/- 14 ms, P<0.005 and Group B: 45 +/- 12 ms, P<0.005). Similar differences between groups were also found for JT dispersion. Multiple regression analysis revealed that among the demographic and clinical variables that were tested, only the echocardiographic degree of the prolapse and anterior mitral leaflet thickness were independently associated with QT dispersion. Holter monitoring showed that the incidence of complex ventricular arrhythmias was also higher in patients with more severe MVP. CONCLUSIONS: Our results indicate that QT and JT dispersions are related to the echocardiographic degree of MVP and mitral leaflet thickness. The echocardiographic assessment of the severity of the prolapse may help to identify a subgroup of patients at increased risk of life-threatening arrhythmias.

Increased plasma endothelin levels in angina patients with rapid coronary artery disease progression.

AIMS: To investigate the association between plasma endothelin levels and rapid coronary artery disease progression, as assessed by quantitative angiography. METHODS AND RESULTS: Changes in diameter were assessed in 224 coronary stenoses of 92 consecutive patients (62 men) with chronic stable angina pectoris who were on a waiting list for routine coronary angioplasty and underwent coronary angiography on two occasions: the first (diagnostic) angiogram was carried out at study entry and the second 5.5+/-3.0 months later, immediately prior to coronary angioplasty. A digital quantitative angiographic analysis system was used to assess differences in stenosis diameter between the first and second angiogram. Plasma immunoreactive endothelin levels were estimated by radioimmunoassay at study entry. Rapid coronary artery disease progression occurred in 29 (31.5%) patients according to pre-established criteria: 12 (41%) had a > or =10% diameter reduction of at least one pre-existing stenosis > or =50%, 10 (34%) had a > or =30% diameter reduction of a pre-existing stenosis <50%, 5 (17%) patients developed a new stenosis and 2 (7%) had progression of a lesion to total occlusion by the second angiogram. Baseline demographic, clinical and angiographic data were similar in patients with and without stenosis progression. Plasma endothelin levels were significantly higher in patients with rapid disease progression than in those without (5.7+/-2.0 pg. ml(-1)vs 3.9+/-1.6 pg. ml(-1), P<0.001). Multiple logistic regression analysis revealed that endothelin was an independent predictor of disease progression (P=0.001). Moreover, endothelin levels above 4.26 pg. ml(-1)(the median of the total endothelin concentrations) were associated with a sixfold increase in the risk of developing rapid stenosis progression. CONCLUSIONS: Plasma endothelin is raised in patients with coronary artery disease progression and may be a marker of risk of rapid stenosis progression. Endothelin may also play a pathogenic role in this process.

Negative stress echocardiographic responses in normotensive and hypertensive patients with angina pectoris, positive exercise stress testing, and normal coronary arteriograms.

OBJECTIVES: To systematically compare the results of dobutamine stress echocardiography in matched groups of hypertensive and normotensive patients with anginal chest pain and normal coronary arteriograms (CPNA). SETTING: University hospital. SUBJECTS: 33 patients with exertional anginal chest pain, a positive exercise stress ECG, and a completely normal coronary arteriogram; 17 had a history of systemic hypertension (14 women; mean (SD) age 57 (6) years), and 16 had no hypertensive history (12 women; age 54 (9) years). METHODS: Ambulatory ECG monitoring, dobutamine stress echocardiography, and thallium-201 single photon emission computed tomography (SPECT) were performed in all subjects. RESULTS: All patients had normal left ventricular systolic function at rest and none fulfilled the criteria for ventricular hypertrophy. Eight normotensive patients and 10 hypertensive patients had perfusion abnormalities on thallium SPECT (p = 0.61). Dobutamine infusion reproduced anginal pain in seven normotensive and seven hypertensive patients (p = 0.88). ST segment depression was also recorded in eight normotensive patients and seven hypertensive patients (p = 0. 61). No patient in either group developed regional wall motion abnormalities during dobutamine stress echocardiography. CONCLUSIONS: Neither hypertensive nor normotensive CPNA patients developed regional wall motion abnormalities during dobutamine stress echocardiography, despite the high prevalence of scintigraphic perfusion defects in both groups and the presence of chest pain and ST segment depression. Thus myocardial ischaemia was not present in either group, or else dobutamine stress echocardiography is insensitive to ischaemia caused by microvascular dysfunction.

Spectral analysis of heart rate variability before and during episodes of nocturnal ischaemia in patients with extensive coronary artery disease.

Spectral analysis of heart rate variability was used to assess autonomic nervous system activity associated with episodes of nocturnal myocardial ischaemia in 32 patients (20 men, age 58 +/- 9 years) with extensive coronary artery disease. Twenty-four hour Holter tape recordings were analysed and spectral indexes of heart rate variability were computed by fast Fourier analysis on 2 min segments covering the period from 10 min before to 10 min after each nocturnal ischaemic episode, defined as ST segment depression > or = 1 mm lasting at least 4 min. Spectral power was measured at low frequencies (LF: 0.06-0.10 Hz) and high frequencies (HF: 0.15-0.40 Hz) and the ratio LF/HF was calculated. RESULTS. A total of 30 episodes of nocturnal ischaemia were analysed. High frequency spectral power showed a clear decrease during the 10 min before the onset of ischaemia, remained steady until the end of the episode, and returned to normal by 6 min after. Low frequency spectral power fluctuated throughout the ischaemic episodes with no clear pattern of variation. The low/high frequency ratio reflected mainly the changes in high frequency. CONCLUSIONS. Sympathetic predominance due to para-sympathetic withdrawal is the principal change in autonomic nervous system activity associated with episodes of nocturnal ischaemia.