4 | Discussion
Periodontitis has a high worldwide prevalence of 40 % - 50 %. This is
not only important for oral health because there is increasing evidence
that periodontitis can promote the development of atherosclerosis and
subsequent diseases such as CHD. The majority of these previous
longitudinal studies investigated patient groups without clinical
symptoms of atherosclerosis or CVD at baseline . However, in two
previous studies, an association between periodontal disease and
recurrent cardiovascular events was shown . Therefore, it can be assumed
that periodontitis may influence cardiovascular outcome after cardiac
surgery. In this study, we examined whether periodontitis was associated
with the incidence of new cardiovascular events after CAGB surgery.
Different periodontitis classification systems were used in order to
compensate disadvantages of a separate classification system. For
instance, in both the CDC classification and the new classification
system bleeding upon probing is not taken into account. However, in
particular the area of the periodontal inflamed tissue may associate
with the systemic inflammatory burden. For that reason, PESA and PISA
were additionally determined as continuous values. PESA allows
determining the amount of periodontal altered pocket epithelium whereas
PISA allows determining the amount of inflamed pocket epithelium .
Among our test group, the prevalence of a severe periodontitis (71.3%,
Table 1) was more than two times as high in comparison to the normal
population because the “Fifth German Oral Health Study” revealed among
younger seniors (65 to 74 year olds) a prevalence of 28.3% [39].
This result may support the importance of severe periodontitis in the
pathogenesis of atherosclerosis and CHD. However, after cross-sectional
comparisons and survival analyzes, we were unable to ascertain that
clinical parameters of periodontitis, oral hygiene habits but also the
caries index were significantly associated with the incidence of new
cardiovascular events. Only a history of early tooth loss due to tooth
loosening among first-degree relatives was associated with increased HR
for new cardiovascular events. Regarding the internal parameters, a PAD
and a previous myocardial infarction were significant and atrial
fibrillation was marginally significant associated with a new event.
Oral anticoagulants and antiarrhythmic drugs were also significantly
associated with a new event, according to cross-sectional comparisons.
Since both drugs are mainly given to patients with atrial fibrillation,
no separate survival analyses were carried out.
The hypothesis that clinical parameters of periodontitis and oral
hygiene habits influence the follow-up after CABG surgery has not been
confirmed by our study. However, the association of a putative familial
aggregation of periodontitis assessed as early tooth loss according
tooth loosening with the cardiovascular endpoint could be important and
should be replicated in further studies. The following hypotheses for
this association are conceivable. At first, members of a family share
conditions, e.g. less self-care, which promote periodontal disease and
CHD. This hypothesis is contradicted by the fact that we could not
demonstrate any significant differences in dental care and plaque index
between the groups with and without the event. Secondly, this
observation may indicate the existence of common genetic risk markers
for periodontitis and CHD. A single nucleotide polymorphisms (SNPs) in
long non-coding RNA ANRIL (antisense noncoding RNA in the INK4locus) were shown to be associated with both, CHD and periodontitis [.
Interestingly, genetic variants of ANRIL was associated with the extent
of elevated levels of CRP and new adverse events within three years
follow-up in patients who had to be hospitalized for treatment CHD .
The positive association between PAD and cardiovascular outcome revealed
in our study has been confirmed by others . It was shown that patients
with PAD had in particular poorer long-term survival rates after CAGB
surgery than patients without PAD . The association between PAD and
long-term survival after CABG may have several explanations. PAD may be
a marker of more severe atherosclerosis and subsequent diseases such as
CHD. Another possibility is that in spite of successful CABG surgery,
the risk of noncardiac mortality may be increased . Chue et al. found
among patients with PAD a higher incidence of comorbidities and they
were generally sicker than patients without PAD .
In our study, a history of myocardial infarction was associated with a
higher incidence of new adverse events after CABG surgery. Another study
supported our results. A history of MI was associated with increased
mortality during the first 30 days after CAGB surgery but not
thereafter. Furthermore, patients with a history of MI developed more
frequently a new MI. Moreover, a previous MI was also associated with a
longer total hospital stay mainly caused by new MI, angina pectoris and
congestive heart failure .
In our study, we observed a higher incidence of postoperative events in
patients with preoperative atrial fibrillation. This result is also
supported by further studies . Preoperative atrial fibrillation was
found associated with increased late cardiac morbidity and mortality,
poor long-term survival, higher risk of all-cause mortality, and
congestive heart failure.