Is the right ventricle the Achilles heel of endurance exercise? I wrote briefly about this subject in 2007 .
In that regard there is more data now about which to fret. A 2011 article by researchers in Australia and Belgium gives reason to believe that endurance exercise affects the left and right ventricles differently and possibly not in a good way .Could endurance exercise induce chronic changes in the structure of the right ventricle such that it is vulnerable to ventricular arrhythmias, similar to those related to an inherited cardiomyopathy (arrhythmogenic right ventricular cardiomyopathy). See here. ARVC is very uncommon in the US but more commonly seen in Europe particularly in Italy where it is said to be the most common cause of sudden cardiac death in young athletes.
The authors studied 40 well trained endurance athletes before an event , immediately afterwards and 6-11 days later.Echocardiograms were done at all three times and cardiac MRs were done at baseline.
Immediately post race, right ventricular ejection fraction was reduced and RV volume was increased while comparable changes were not present in the left ventricle. RV function did recover by one week except for an echo derived index called "global strain".(In echo lingo strain means deformation which can be determined by tissue Doppler techniques)
Five of the 39 athletes demonstrated delayed gadolinium enhancement (DGE) in the ventricular septum. These changes believed to represent fibrosis were more common in the athletes who had been competitive endurance athletes longer and the authors suggested that the areas of fibrosis noted on the gadolinium scan were in the area of the septum which bulges into the left ventricle as a result of the tissue deformation noted in the right ventricle.
As the authors stated, the long-term clinical significance warrants further study.Will there be re-modelling of the RV in such a way as to predispose to ventricular arrhythmias?
Another publication by some of the same authors had previously examined the prevalence of gene mutations in athletes with complex ventricular arrhythmias. Specifically they looked for desmosomal gene mutations of the type typical of ARVC ( Arrhythmogenic Right Ventricular Cardiomyopathy). Desmosomes are complexes of protein that function to facilitate cell to cell adhesion. In 20 of the 47 cases no desmosome gene mutations was identified.A suggestion was made that prolonged endurance exercise could bring about remodeling of the right ventricle which would predispose to ventricular arrhythmias even in some athletes who do not have the recognized desmosomal gene mutation..I wrote in more detail about this study here.
The right ventricular issue may well be worth worrying a bit about but the small but consistently increased incidence of atrial fibrillation in long term exercisers has a more robust data base in its support.