Lifetime exercise dose and ventricular arrhythmias in patients with mitral valve prolapse

Abstract

Aims: Patients with mitral valve prolapse (MVP) have high risk of life-threatening ventricular arrhythmias (VAs). Data on the impact of exercise on arrhythmic risk in these patients are lacking. We explored whether lifetime exercise dose was associated with severe VA and with established risk factors in patients with MVP. Furthermore, we explored the circumstances at the VA event.

Methods and results: In this retrospective cohort study, we included patients with MVP and assessed lifetime exercise dose as metabolic equivalents of task (MET) hours/week. Severe VA was defined as sustained ventricular tachycardia or fibrillation, aborted cardiac arrest, and appropriate shock by a primary preventive implantable cardioverter defibrillator. We included 136 MVP patients (48 years [interquartile range (IQR) 35-59], 61% female), and 17 (13%) had previous severe VA. The lifetime exercise dose did not differ in patients with and without severe VA (17 MET h/week [IQR 9-27] vs. 14 MET h/week [IQR 6-31], P = 0.34). Lifetime exercise dose > 9.6 MET h/week was a borderline significant marker for severe VA (OR 3.38, 95% CI 0.92-12.40, P = 0.07), while not when adjusted for age (OR 2.63, 95% CI 0.66-10.56, P = 0.17). Ventricular arrhythmia events occurred most frequently during wakeful rest (53%), followed by exercise (29%) and sleep (12%).

Conclusion: We found no clear association between moderate lifetime exercise dose and severe VA in patients with MVP. We cannot exclude an upper threshold for safe levels of exercise. Further studies are needed to explore exercise and risk of severe VA.

Keywords: Exercise; High intensity exercise; Mitral annular disjunction; Mitral valve prolapse; Sudden cardiac death.

Graphical Abstract

Figure 1

Study population, recruitment, and severe ventricular arrhythmia. A total of 160 patients with mitral valve prolapse were invited to an exercise questionnaire of which 136 patients responded. Seventeen had experienced severe ventricular arrhythmia and were interviewed about the activity performed at time of the event. ACA, aborted cardiac arrest; ICD, implantable cardioverter defibrillator; VT, ventricular tachycardia.

Figure 2

Cumulative incidence of severe ventricular arrhythmia according to total lifetime exercise dose below or above 9.6 MET h/week. Panel A shows the cumulative incidence plot displaying higher age-related incidence of severe ventricular arrhythmia in MVP patients with exercise dose above 9.6 MET h/week compared to those with exercise dose below 9.6 MET h/week. Panel B shows the univariate and multivariate logistic regression models for the association between severe VA, exercise dose above 9.6 MET h/week, and age. CI, confidence interval; MET, metabolic equivalents of task; OR, odds ratio; VA, ventricular arrhythmia.

Figure 3

Distribution of lifetime exercise dose and severe ventricular arrhythmias in MVP patients by age. The scatter plot shows the distribution of lifetime exercise dose in MET h/week (y-axis) by the patient’s age at inclusion or at their severe ventricular event (x-axis). There was no association between exercise dose and ventricular arrhythmias [filled dots (OR 1.31, 95% CI 0.61–2.81, per 10-fold increase, P = 0.49)]. There was no association between exercise dose and age in those with arrhythmic events (filled dots, solid line, P = 0.58), nor in those without severe events (open circles, dotted line, P = 0.07). MET, metabolic equivalents of task; MVP, mitral valve prolapse; VA, ventricular arrhythmia.

Figure 4

Receiver operating characteristic (ROC) curve and logistic regression models comparing number of risk factors and the addition of exercise to detect severe ventricular arrhythmias. The ROC curves for two logistic regression models. Model 1 includes the number of risk factors to detect risk of severe ventricular arrhythmia. Model 2 includes the number of risk factors and total lifetime exercise dose to detect the risk of severe ventricular arrhythmia. Adding total lifetime exercise dose to the model did not improve the detection of risk. The bar charts show the comparison of the area under the curve (AUC) of two logistic regression models. The table shows the odds ratios (OR) and P-values from the two logistic regression models. AIC, Akaike information criterion; AUC, area under the curve.