Table 1.

List of studies included and patient characteristics

Study	Study design, blinding	Number of participants (sauna/control)	NYHA classes at baseline for all groups. If numerical = at average	Mean ejection fraction: sauna/control	Mean age: sauna /control	Male %	Ischemic cardiomyopathy (sauna/control, % of respective group)	Medications, % of sauna/control			Implantable cardioverter‐defibrillator, cardiac resynchronisation therapy‐device (% of sauna/control)	Location	Quality assesment: Downs and Black score (of 32)
								ACE (Angiotensin Converting Enzyme)‐inhibitors or (ACE‐I) Angiotensine II receptro‐blockers (ARB)	B‐blockers	Diuretics
Kihara 2002 23	Controlled trial, no	20/10	II, III	38/32	62/64	60	15/unknown	“All patients”	“Most patients”	“All patients”	Not listed	Japan	16
Kihara 2004 24	Randomized controlled trial (RCT), no	20/10	II, III	29/29	59/59	70	20/20	95/90	55/40	95/100	Not listed	Japan	19
Miyata 2008 25	RCT, no	112/76	2.61, 2.51	31.6/36.6	63/66	66	15/9	Data not available	Data not available	Data not available	Not listed	Japan	20
Kihara 2009 16	Retrospective study, no	64/65	2.6	38.5/35.8	61.9/64.6	64	26/21	69/65	61/57	73/83	Not listed	Japan	19
Kuwahata 2011 26	RCT, no	27/27	II, III, IV	31/33	63/64	70	37/37	ACE‐I 52/63 ARB 48/37	93/93	100/100	—	Japan	19
Fujita 2011 27	RCT, no	20/20	II, III	31.8/34.3	64/65	83	30/35	100/95	90/95	Not listed	—	Japan	19
Tei 2016 28	RCT, no	76/73	II, III, IV	30.2/30.9	66/66	61	26/30	ACE‐I 58/55 ARB 24/27	86/88	97/99	CRT‐P 1/4 CRT‐D 18/22, ICD 2/4	Japan	21
Ichiki 2017 29 (substudy of Tei 2016)	RCT, no	76/73	II, III, IV	30.2/30.9	66/66	61	26/30	ACE‐I 58/55 ARB 24/27	86/88	97/99	CRT‐P 1/4 CRT‐D 18/22, ICD 2/4	Japan	21
Basford 2009 30	Crossover, no	9‐crossover	II, III, IV	20	72	67	Not listed	Not listed	Not listed	Not listed	Excluded from the study	USA	—