1. Study characteristics.

Study design (publication type)	Participants	Age (years)	Definition of CSA	Comparators	Duration of intervention period (washout)
Bonnet 1990 Cross‐over (full report)	5 men with primary CSA	Average 70 (range 65–74)	Central apnoeas were scored when there was an event of complete absence of chest movement from both chest leads and a complete absence of airflow throughout the event (lasting >10 seconds).	Triazolam 0.125 mg versus triazolam 0.250 mg (once daily) versus placebo	3 days (≥ 1 week)
Giannoni 2020a Cross‐over (full report)	16 men with systolic heart failure (LVEF < 50%) and moderate‐severe CSA	Mean 71.3 (SD 5.8)	Echocardiographic evidence of LVEF < 50% and nocturnal AHI ≥ 15 events/hour	Buspirone 15 mg (3 times daily) versus placebo	1 week (1 week)
Javaheri 1996 Cross‐over (full report)	15 men with compensated heart failure (LVEF ≤ 45%) and AHI > 10 events/hour	Not reported (adults)	Polysomnograms showed periodic breathing, with > 10 episodes of apnoea and hypopnoea/hour.	Theophylline 3.3 mg/kg (twice daily) versus placebo	5 days (1 week)
Javaheri 2006 Cross‐over (full report)	12 men with systolic heart failure whose initial polysomnograms showed CSB with AHI > 15 events/hour	Mean 66 (SD 6)	Systolic heart failure (initial polysomnograms showed CSB with an AHI > 15 events/hour)	Acetazolamide 3.5 mg/kg (once daily) versus placebo	6 days (2 weeks)
Sorokina 2019a RCT (abstract)	18 people (mostly men) with CSA associated with CHF	Not reported (adults)	AHI > 15 events/hour by echocardiographic evidence were considered as living with CSA. CHF ranged from II to III NYHA functional classes.	Standard medical treatment + acetazolamide 250 mg versus standard medical treatment without acetazolamide	Not reported; follow‐up was 12 months

AHI: apnoea‐hypopnoea index; CHF: chronic heart failure; CSA: central sleep apnoea; CSB: Cheyne‐Stokes breathing; LVEF: left ventricular ejection fraction; NYHA: New York Heart Association; SD: standard deviation.