Positive independent relationship between periodontitis and a first myocardial infarction

Rydén L, Buhlin K, Ekstrand E, et al.
Circulation. 2016;133:576-583

Background

Periodontitis is mainly due to Gram-negative bacteria that cause chronic inflammation affecting the underlying structures and leading to loss of connective tissue and bone support [1]. Chronic inflammation and inflammatory activation stimulate the course of atherosclerosis and increase the risk for plaque rupture, leading to acute coronary syndromes [2,3].  
A relationship between periodontitis and cardiovascular disease has been described [4,5], however the nature of this relationship is disputed [6]. Theoretically, a causal relationship could be explained by the transfer of microorganisms from dental pockets into the blood stream when chewing or tooth brushing [5]. Interestingly, DNA from oral microorganisms has been detected in atherosclerotic plaques [7,8].
This Swedish large case-control study tested the hypothesis of the existence of an independent relationship between periodontitis and the occurrence of a first myocardial infarction (MI).

Main results

• Periodontal status verified by radiographic bone loss
- Mild to moderate periodontitis was documented in 33% of patients and 29% of controls
- Severe periodontitis was present in 10% of patients and 4% of controls
• There was an increased risk for MI among individuals with moderate to severe periodontitis:
- Crude OR: 1.49; 95%CI: 1.21–1.83
- OR after excluding edentulous individuals: 1.46; 95%CI: 1.19–1.80
- Adjusted OR: 1.28; 95%CI: 1.03–1.60
Smoking and dysglycaemia were the most important potential confounders

Conclusion

The risk of a first MI was significantly increased in patients with periodontitis even after adjustment for confounding factors. These findings strengthen the possibility of an independent relationship between periodontitis and MI, and justify the further exploration of underlying pathophysiological mechanisms.

Editorial comment [9]

Stewart and West highlight that the PAROKRANK study strengthens the evidence for an independent relationship between periodontal disease and first myocardial infarction, however, it does not support a recommendation to treat periodontal disease with the objective of reducing cardiovascular risk. ‘Should treatment of periodontal disease be recommended to reduce the risk of cardiovascular disease? No, or only with reservations; because the key evidence needed, that treatment of periodontal disease lowers the risk of major adverse cardiovascular events, is missing. For this a large randomized clinical trial is needed….In 2012, an American Heart Association scientific statement concluded that there is no class A or B evidence that periodontal disease causes atherosclerotic vascular disease, and cautioned that statements that imply a causative association, or that specific therapeutic interventions may be useful, are unwarranted. This caution remains appropriate. The PAROKRANK study adds to the strong evidence for an association between periodontitis and myocardial infarction, but does not prove causation. However, knowledge that the association is at least partly explained by common risk factors is important, because it provides further evidence that strategies to reduce cardiovascular risk, such as the American Heart Association’s Life’s Simple 7, are also likely to benefit other determinants of good health.‘

Find this article online at Circulation

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