| Study | Reason for exclusion |
|---|---|
| Adarsh 2008 | No randomisation; not an RCT |
| Azuma 1992 | Title is not related to our main area of interest |
| Baggio 1993 | Not a RCT |
| Belardinelli 2005 | RCT study with a cross‐over design; first phase data are unavailable |
| Belardinelli 2008 | Title is not related to our main area of interest |
| Cascone 1985 | Not a RCT |
| Chen 2017 | Not a RCT, review article |
| Chen 2018 | Not a RCT, no control arm |
| Chew 2008 | Title is not related to our main area of interest |
| Davini 1992 | Title is not related to our main area of interest |
| Fedacko 2009 | Participants in the study did not have heart failure |
| Hall 1990 | Not a RCT |
| Hanping 1997 | Title is not related to our main area of interest |
| Hofman‐Bang 1995 | RCT study with a cross‐over design; first phase data are unavailable |
| IRCT2015070223018N1 | Peoeple with heart disease were excluded |
| Ishiyama 1976 | Not a RCT |
| Iwabuchi 1972 | Not a RCT |
| Johansson 2013 | Investigating coenzyme Q10 combined with selenium |
| JPRN‐UMIN000007695 | Not investigating coenzyme Q10 |
| JPRN‐UMIN000020203 | Not a RCT, no control arm |
| JPRN‐UMIN000027248 | Study meets inclusion criteria, but was terminated before it was finished, and no results were generated or reported, according to the first author. |
| Khatta 1999 | Title is not related to our main area of interest |
| Kukharchik 2016 | Abstract has no usable data, authors were contacted but did not respond |
| Kukharchik 2016a | Abstract has no usable data, authors were contacted but did not respond |
| Kukharchik 2017 | Abstract has no usable data, authors were contacted but did not respond |
| Kumar 2007 | Title is not related to our main area of interest |
| Kumar 2015 | Abstract has no usable data, authors were contacted but did not respond |
| Lampertico 1993 | Not a RCT |
| Langsjoen 1985 | Not a RCT |
| Langsjoen 1985a | Title is related to our main area of interest, but none of the selected participants were in frank congestive heart failure |
| Langsjoen 1988 | Not a RCT |
| Langsjoen 1990 | Not a RCT |
| Langsjoen 1994 | Not a RCT |
| Langsjoen 2008 | Title is not related to our main area of interest |
| Leonova 2018 | Abstract has no usable data, authors were contacted but did not respond |
| Manzoli 1990 | Not a RCT |
| Mazzola 1987 | RCT study with a cross‐over design; first phase data are unavailable |
| McMurray 2009 | Not investigating supplemental coenzyme Q10 |
| Miyazaki 2013 | Not a RCT, not investigating supplemental coenzyme Q10 |
| Morisco 1994 | RCT study with a cross‐over design; first phase data are unavailable |
| Mortensen 1985 | Not a RCT |
| NCT03586414 | Includes only healthy individuals, people with cardiovascular disease were excluded |
| Nishimura 1996 | Title is not related to our main area of interest |
| Oleg 2016 | Abstract has no usable data, authors were contacted but did not respond |
| Permanetter 1992 | RCT study with a cross‐over design; first phase data are unavailable |
| Poggesi 1991 | Title is related to our main area of interest, but none of the selected participants were in frank congestive heart failure |
| Pourmoghaddas 2014 | Investigating coenzyme Q10 combined with atorvastatin |
| Rivera 2017 | Did not include people with heart failure |
| Sacher 1997 | Not a RCT |
| Saurabh 2014 | No usable data in the abstract; authors contacted but did not respond |
| Schneeberger 1984 | RCT study with a cross‐over design; first phase data are unavailable |
| Sinatra 2000 | Title is not related to our main area of interest |
| Sinatra 2004 | Title is not related to our main area of interest |
| Turk 2013 | Did not include people with heart failure |
| Watson 1999 | RCT study with a cross‐over design; first phase data are unavailable |
| Witte 2005 | Title is not related to our main area of interest |
RCT: randomised controlled trial