Background: Sleep apnea is an important risk factor for cardiovascular diseases, but whether the severity of sleep-disordered breathing (SDB) changes in the acute phase of myocardial infarction (MI) has not been well determined, nor has it been determined what type of SDB, central or obstructive, (CSA or OSA) is exacerbated.
Methods and results: Polysomnography was performed in patients with acute phase of MI during the acute (days 3-5) and chronic (day 14) phases. On the same day, the ventilatory equivalent (VE)/carbon dioxide production (VCO(2)) slope, urinary catecholamines secretion and arterial carbon dioxide tension were assessed before sleep. The apnea/hypopnea index was significantly decreased in the chronic phase (13.26+/-11.30 vs 6.97+/-5.67, p<0.05). The distribution of the types of SDB was unchanged, indicating both CSA and OSA can be exacerbated in the acute phase of MI. The VE/VCO(2) slope and arterial carbon dioxide tension before sleep were also unchanged. Urinary norepinephrine secretion was slightly decreased, although the difference was not significant.
Conclusions: SDB is temporarily worsened in the acute phase of AMI and both CSA and OSA are worsened in AMI.