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Correspondence |

Factors That May Influence Apnea-Hypopnea Index in Patients With Acute Myocardial Infarction FREE TO VIEW

Ahmed Salem BaHammam, MD, FCCP
Author and Funding Information

Affiliations: Dr. BaHammam is affiliated with the Sleep Disorders Center, King Saud University.

Correspondence to: Ahmed S. BaHammam, MD, FCCP, Sleep Disorders Center, King Saud University, PO Box 225503, Riyadh 11324, Saudi Arabia; e-mail: ashammam2@gmail.com; ashammam@ksu.edu.sa


Financial/nonfinancial disclosures: The author has reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/site/misc/reprints.xhtml).


© 2009 American College of Chest Physicians


Chest. 2009;136(5):1444-1445. doi:10.1378/chest.09-1413
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To the Editor:

In a recent issue of CHEST (June 2009), Lee et al1 reported a very high prevalence of obstructive sleep apnea (OSA) [65.7%] in patients with acute myocardial infarction (AMI) despite using an apnea-hypopnea index (AHI) value of ≥ 15 events per hour as being diagnostic of OSA. This prevalence is higher than that reported in previous studies,24 which used a lower AHI cutoff of 10 events per hour. The authors attributed this discrepancy to a number of factors, including differences in the timing of sleep studies and the characteristics of the studied population, which included a heterogeneous group of patients.

In a previous study,2 using level II, comprehensive, unattended sleep studies within 4 days of admission to the coronary care unit (CCU) in a group of patients who had experienced a first AMI and were comparable to the group studied by Lee et al1 in terms of age, body mass index, gender distribution, and timing of sleep studies, we reported an OSA prevalence of 52% using AHI prevalence cutoffs of 10 events per hour, and 36% at an AHI of > 20 events per hour. In our view, the high prevalence of OSA in the study by Lee et al1 can be partially attributed to a number of factors. The authors did not exclude conditions that may increase the prevalence of sleep-disordered breathing in patients who are in the acute phase of an AMI, such as those patients receiving sedation or narcotics, those with a decreased level of consciousness, alcoholic patients, patients with COPD, and those patients with neurologic disorders such as stroke. Additionally, as sleep position was not monitored, the effect of sleep position on AHI cannot be excluded. Patients are more likely to lie in the supine position in the ICU setting compared with their own home, which may in turn increase the AHI.

Lee et al1 raised the possibility that performing sleep studies during an acute cardiovascular event might increase the AHI, which in turn may partially explain the difference between the findings of the present study and those of older studies. To explore this possibility, we repeated a level I attended sleep study in the sleep disorders center 6 months after the acute event. AHI, obstructive apnea index, and the duration of obstructive apnea did not change over the 6-month period. On the other hand, central apnea index and central apnea duration were significantly lower in the follow-up studies.2 Future studies should have stringent control of possible confounders that may affect sleep-disordered breathing in patients with AMI.

Lee CH, Khoo SM, Tai BC, et al. Obstructive sleep apnea in patients admitted for acute myocardial infarction: prevalence, predictors, and effect on microvascular perfusion. Chest. 2009;135:1488-1495. [PubMed] [CrossRef]
 
BaHammam A, Al-Mobeireek A, Al-Nozha M, et al. Behaviour and time-course of sleep disordered breathing in patients with acute coronary syndromes. Int J Clin Pract. 2005;59:874-880. [PubMed]
 
Mehra R, Principe-Rodriguez K, Kirchner HL, et al. Sleep apnea in acute coronary syndrome: high prevalence but low impact on 6-month outcome. Sleep Med. 2006;7:521-528. [PubMed]
 
Skinner MA, Choudhury MS, Homan SD, et al. Accuracy of monitoring for sleep-related breathing disorders in the coronary care unit. Chest. 2005;127:66-71. [PubMed]
 

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References

Lee CH, Khoo SM, Tai BC, et al. Obstructive sleep apnea in patients admitted for acute myocardial infarction: prevalence, predictors, and effect on microvascular perfusion. Chest. 2009;135:1488-1495. [PubMed] [CrossRef]
 
BaHammam A, Al-Mobeireek A, Al-Nozha M, et al. Behaviour and time-course of sleep disordered breathing in patients with acute coronary syndromes. Int J Clin Pract. 2005;59:874-880. [PubMed]
 
Mehra R, Principe-Rodriguez K, Kirchner HL, et al. Sleep apnea in acute coronary syndrome: high prevalence but low impact on 6-month outcome. Sleep Med. 2006;7:521-528. [PubMed]
 
Skinner MA, Choudhury MS, Homan SD, et al. Accuracy of monitoring for sleep-related breathing disorders in the coronary care unit. Chest. 2005;127:66-71. [PubMed]
 
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