Original search yielded 2616 results and 12 more were added based on the exploration of the references of systematic reviews and meta-analyses related to hypertrophic cardiomyopathy. When full texts were not available online, authors were contacted after an initial screening for title and abstract. A flow diagram of the search process is available in Figure 1. One hundred and two full texts were read after the first screening, of which, 69 were included for qualitative synthesis. The protocol was designed ad hoc and not published. All data concerning methodological designs are showed in Table 1. They included 11,672 patients which were 48 ± 14 years old and had an average body mass index of 26.9 ± 6.5 kg/m² as evaluated with data from 21 studies and 6558 patients. In total, 65.9% of them were men and 34.1% women. In 18 of the 69 articles, at least one extracardiac variable was included, among which the presence of diabetes and pathologies involving the lipidic metabolism were the most common with 14 and 7 times reported, respectively. The presence of diabetes was calculated with data from 3665 patients with a prevalence of 7.6%; and from 1927 patients for dyslipidemias with a prevalence of 45.1%. Other comorbidities such as hypertension and smoking habit were present in 32.8% and 30.6% of patients, respectively.

Management of the pharmacological therapy showed 12 different options and was evaluated in 60 of the 69 studies. In seven of them, the use of drugs was recorded but no further information about its management was provided. In 26 of the 53 remaining, drugs were not discontinued before the study; in 6, the researchers provided it; and in 1, none of the subjects were on medication. Finally, in the 20 remaining studies, drugs were discontinued with variable time from 5 days to 12 h prior to the exercise test.

Treadmill was the most common ergometer employed (n = 37 studies), followed by upright cycle-ergometer (n = 16 studies), supine and semi-supine cycle-ergometers (n = 6 studies each). Bruce’s protocol [83] and its modified version [84] were the most frequently used, while there was a marked heterogeneity in the protocols employed in the cycle-ergometers. The initial intensity was set between 0 W and 28 W with increments ranging from 5 W to 30 W and lapses lasting 1 to 3 min. There were 2 publications where the intensity was increased in a ramp-like fashion adding 1–2 W each 1–6 s.