Prevalence of QTc prolongation in women with mitral valve prolapse

Meary angle for the prediction of mitral valve prolapse risk in non-syndromic patients with pes planus, a cross-sectional study

Objectives

Mitral Valve Prolapse (MVP) is a common valvular abnormality accounting for 2% of the population. There is a reported association between pes planus (PP) and MVP in some syndromes such as Marfan. However, this association has not been tested in non-syndromic cases. The primary outcome of this study is to measure the prevalence of MVP in a population of patients with PP. The secondary outcome parameter is to determine if the Meary angle (MA), a measure of the severity of flat foot, can be effectively used in the prediction of the presence of MVP. Forty-one patients with PP were screened using a lateral x-ray foot to determine MA while echocardiography was utilized to identify the presence and grade of MVP.

Results

88% of screened patients were diagnosed with MVP. MA was correlated with the grade of MVP and showed high diagnostic accuracy (sensitivity 100% and specificity 90%) in predicting MVP risk when higher than 5. Children with PP are at a higher risk for MVP than the general population. Accordingly, the utilization of MA in such a specific population for the determination of patients at a higher need for echocardiography seems to be a worthwhile strategy in diagnosing MVP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-022-06032-0.

Increased dispersion of refractoriness in the absence of QT prolongation in patients with mitral valve prolapse and ventricular arrhythmias

BACKGROUND

The mechanism responsible for the reported high incidence of ventricular arrhythmias in mitral valve prolapse is not clear. Electrocardiographic studies show an increased occurrence of repolarisation abnormalities on the 12 lead surface electrocardiogram, indicating regional differences in ventricular recovery. The purpose of this study was to investigate whether dispersion of refractoriness was an arrhythmogenic mechanism.

METHODS

QT dispersion was measured in 32 patients with echocardiographically documented mitral valve prolapse and ventricular arrhythmias on 24 hour Holter recordings. QT dispersion was defined as the difference between the maximum and minimum average QT interval in any of the 12 leads of the surface electrocardiogram. QT dispersion corrected for heart rate was calculated by Bazett's formula. The results were compared with the data from 32 matched controls without a history of cardiac disease. Patients taking drugs that influence the QT interval and patients with a QRS duration > 120 ms were excluded.

RESULTS

QT dispersion was greater in patients with mitral valve prolapse than in matched controls (60 (20) v 39 (11 ms) respectively, P < or = 0.001) as was corrected QT (64 (20 ms) v 43 (12 ms) respectively, P < or = 0.001). There was no significant difference in minimum or maximum QT intervals between the two groups.

CONCLUSIONS

QT dispersion on the 12 lead surface electrocardiogram was greater in patients with mitral valve prolapse with ventricular arrhythmias than in normal controls, but the maximum QT interval was not increased. The results accord with the hypothesis that regional shortening and lengthening of repolarisation times in patients with mitral valve prolapse may account for the increased dispersion of refractoriness.

Ventricular arrhythmias and the autonomic tone in patients with mitral valve prolapse

The aim of this study was to evaluate a possible relation between the autonomic tone determined by daily urine catecholamine excretion and the incidence of ventricular arrhythmias (VA) in patients with mitral valve prolapse (MVP). The study included 53 patients (31 women and 22 men) aged 19-52 years (mean age 32.7). The diagnosis of MVP was based on medical history, physical examination, and echocardiography. Cardiac arrhythmias were detected by Holter monitoring and classified according to Lown grades. Daily heart rate and duration of corrected QT interval using Basett's formula were also analyzed. Daily urine adrenaline and noradrenaline levels were determined fluorometrically by Von Euler and Lishajko's method. The patients with Lown's grade III-V VA were evaluated with particular consideration. Student's t-test was used for statistical analysis. On Holter monitoring 26 patients showed VA, including 6 with grade I, 11 with grade II, 2 with grade III, 4 with grade IV, and 3 with grade V according to Lown's classification. The remaining 27 patients were free of cardiac arrhythmias. Mean daily heart rate ranged from 54-93 beats/min (73 +/- 8.44, mean +/- SD) and corrected QT from 336-494 ms (411 +/- 37.17). Daily adrenaline and noradrenaline excretion for the whole group of patients were 0.01-16.2 micrograms (2.1 +/- 2.38) and 1.6-31.0 micrograms (13.1 +/- 7.27), respectively, which was within normal range. However, the patients with serious ventricular arrhythmias showed significantly higher daily adrenaline excretion. Individual analysis of two-thirds of patients with ventricular arrhythmias grade III-V showed daily urine noradrenaline levels exceeding mean values for the whole group.(ABSTRACT TRUNCATED AT 250 WORDS)

Long QT syndrome presenting as a seizure

A 21-year-old woman was brought to the emergency department after being found unconscious in a hotel lobby. On presentation, she was awake but confused. The initial evaluation revealed no evidence of trauma, metabolic abnormality, drug ingestion, or intracranial process. The only abnormality noted was electrocardiographic, and included a long QT interval as well as occasional atrial and junctional beats within a normal sinus rhythm. While in the department the patient developed tonic-clonic activity and was concurrently noted to have developed ventricular tachycardia. A precordial thump was given with the simultaneous cessation of the arrythmia and the seizure. After definitive electrophysiologic study, the diagnosis of long QT syndrome was made. Treatment consisting of beta blockade and pacemaker insertion prevented further arrythmia or seizure activity. Long QT syndrome should be considered a possible etiology in any patient presenting with new onset seizures, especially in the young.