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

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.

Non-sustained ventricular arrhythmias at exercise ECG predict severe ventricular arrhythmias in arrhythmic mitral valve prolapse

Background

A subset of patients with mitral valve prolapse experience ventricular arrhythmias (VA) and even sudden cardiac death, defined as arrhythmic mitral valve prolapse (AMVP). Risk stratification of VA is challenging in this relatively young population. The predictive role of exercise testing has not been investigated.

Purpose

We aimed to explore if VA burden on exercise ECG can predict severe ventricular arrhythmic events in AMVP patients.

Methods

We included consecutive AMVP patients without prior severe VA referred to our tertiary center. Exercise bicycle ECG test by standard protocol was performed at inclusion. Non-sustained VT (nsVT) during exercise testing was defined as ≥3 consecutive ventricular beats with a rate ≥100/min lasting <30 seconds. Our endpoint of severe VA during follow-up was defined as aborted cardiac arrest, sustained ventricular tachycardia, nsVT with syncope or appropriate ICD shock therapy detected by either ECG, Holter monitoring, implantable loop recorder or primary preventive ICD.

Results

We included 91 AMVP patients without prior severe VA (51±16 years of age, 63% women) with exercise test at baseline. NsVT occurred in 5 patients during exercise testing. During 67±7 months of follow-up, 5 (5.5%) patients experienced severe VA. In all, 3 of the 5 (60%) with nsVT at exercise test experienced severe VA during follow-up, compared to only 2 of 86 (2%) without nsVT at exercise testing (age adjusted hazard ratio [HR] 35 [95% CI 5–249], p<0.001). Survival free from severe VA was worse in those with nsVT at exercise test (log rank p<0.001) (Figure 1).

Conclusions

Non-sustained VT occurring during exercise ECG testing was a strong marker of subsequent severe VA in AMVP patients without previous severe VA. These novel findings indicate that exercise testing may improve risk stratification in AMVP patients.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): The Research Council of Norway.