Pericardial effusion is a common finding in clinical practice either as incidental finding or manifestation of a systemic or cardiac disease. The spectrum of pericardial effusions ranges from mild asymptomatic effusions to cardiac tamponade. Moreover, pericardial effusion may accumulate slowly or suddenly(1).Pericardial effusion is very common after cardiac surgery. Despite the high incidence of effusion, the clinical approach to this problem remains controversial. Once pericardial effusion is documented, serial echocardiographic studies are frequently performed, at considerable expense(2). Unfortunately, there are few epidemiological data on the incidence and prevalence of such effusions in the clinical setting. In Maria Vittoria hospital, an urban general hospital in Torino and an Italian referral center for pericardial diseases, the mean annual incidence and prevalence of pericardial effusion have been, respectively, 3 and 9% in a 6-year experience of the echo laboratory (2000–05) (3). Such data mainly depend on the epidemiological background (especially developed vs. developing country, where tuberculosis is a leading cause of pericardial disease and concurrent HIV infection may have an important promoting role) (4), the institutional setting (tertiary referral center compared to secondary and general hospitals), and the availability of specific subspecialties (especially nephrology, rheumatology, and oncology). Furthermore, since postoperative PE or pericardial tamponade (PT) may present without prominent clinical signs and findings, there is a potential risk for life-threatening events. The delayed presentation of PE or PT may arise several days to weeks after the operation. In these clinical situations, early diagnosis would aid in the early treatment(5).    Pericardial drainage procedures can be performed for diagnostic or therapeutic purposes (patients with cardiac tamponade). In patients without hemodynamic compromise the diagnostic yield of pericardial fluid or pericardial tissue is very low(6). Patients with echocardiographic collapses rarely require pericardial drainage for therapeutic purposes during the initial admission. Therefore, pericardial drainage procedures are not justified on a routine basis in patients without hemodynamic compromise. Three exceptions to this rule should be noted. Patients with a strong suspicion of purulent or tuberculous pericarditis merit invasive pericardial procedures(7). In contrast, in patients with underlying malignancies examination of pericardial fluid is indicated so as to determine whether the effusion is secondary to neoplastic pericardial involvement or is an epiphenomenon (non-malignant effusion) related to the management of the cancer (such as previous thoracic irradiation) or effusions of unknown origin(7). In a nutshell, a wide variety of pathologic conditions may cause pericardial effusion leading to pericardial tamponade. Cardiac tamponade requires drainage to prevent cardiac decompensation and death. The effusion can be drained by needle or catheter pericardiocentesis, subxiphoid pericardial drainage(8),pericardial window performed through a left anterior thoracotomy(9),  pericardiectomy performed by an open thoracotomy(10), or video-assisted thorascopic (VATS) pericardiectomy(11). The most effective method of drainage to prevent recurrence is subject to controversy(12). In the present study, our primary goal was to assess the benefits and drawbacks of posterior pericardial drainage in patients undergoing heart surgery.Study Selection and CriteriaSearch results were screened by scanning abstracts for the following Inclusion Criteria1- Randomized controlled trials (RCTs) and controlled clinical trials (CCTs).2- Study comparing strategy of posterior pericardial drainage with no intervention to the pericardium during heart surgery.3- Studies reporting outcomes of interest within the investigated follow-up.Exclusion Criteria1- Narrative reviews or case reports.2- Non RCTs.The study was done according to the ethical board of King Abdulaziz university.Statistical Analysis• Cochran Q test was used.• Primary index Statistics: Odds ratios (ORs) and 95% confidence intervals (CIs) as for dichotomous outcomes.• Continuous outcomes: mean difference and corresponding 95% CIs calculated by the use of a random effects model.• Pooled ORs were calculated via the Mantel-Haenszel model (13)with weight assigned to each included study adjusted to include a measure of variation (?2) in the effects reported between studies.• In the  case that  degree of heterogeneity exceeded 40%, an inverse variance (DerSimonian-Laird) random-effects model was applied.      As a preferred approach when intervention effects are small (ORs are close to one) and events are not particularly common, estimates were calculated by the use of the fixed-effects Peto method(14). In case there were “0 events” reported in both arms, calculations were repeated, as a sensitivity analysis, by the use of risk difference and respective 95% CIs.Moreover, an attempt was made to explore the possible relationship between age, sex, hypertension, type 2 diabetes, type of the surgery, mean number of grafts, duration of cardiopulmonary bypass, cross clamp, and study total number of patients and the occurrence of primary endpoint. v. 2 (Biostat, Englewood, NJ) (15) were used for statistical computations. P values ?.05 were considered statistically significant and reported as 2-sided, without adjustment for multiple comparisons.RESULTS    Searches identified 1174 publications in addition to another 21 publications that were found through manual research.  After removal of duplicates, abstracts and titles,733 publications were assessed as identified from title and abstract, and 230 papers were excluded. 87 papers full text could not be retrieved and another 340 papers with the same cohort. There were also 317 papers excluded because they did not compare different surgical techniques or did not report an adhesion-related outcome. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) (16)guidelines in reporting the results. Figure 1Most of the studies included 2 drains which were placed at the end of surgery: one in the left pleural cavity while the other was placed in the anterior mediastinum, the pericardium however was left open anteriorly. PP was and comprised a longitudinal, 4-cm long incision parallel and posterior to the phrenic nerve, extending from left inferior pulmonary vein to the diaphragm in most cases. Zhao et al. (25) reported intervention-related complications; one case of postoperative bleeding due to dropping of the hemoclip from the inverse-T incision.      Furthermore, Tables 1 represents baseline characteristics of all studies included in the present meta-analysis while table 2 demonstrates the secondary medical condition of the cases

CPB: Cardiopulmonary bypass, crossclamp, aortic cross
clamp; HT, hypertension; DM,
diabetes mellitus; CABG, coronary artery bypass
grafting; nd, not done; NR,
not reported; NA, not applicable; OPCAB,
off-pump coronary artery bypass.

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Primary Endpoint

       A funnel plot constructed for the primary endpoint revealed signs of
moderate asymmetry (Figure E1, A),
but this was not significant (Egger test, P = .11). Fourteen
studies (n = 2844) were included. Individual and overall ORs for cardiac tamponade
are depicted in Figure 2.

     

      

     Posterior pericardial drainage was
associated with a significant approximately 90% reduction of the odds of cardiac tamponade compared
with the control group: OR (95% CI) 0.13 (0.07-0.25); P 

 

Table 3: comparison
between posterior pericardial drainage (intervention) and control group for
prevention of primary endpoint cardiac tamponade after heart surgery

Death or
Cardiac Arrest

     No signs of
publication bias detected in the analysis of mortality or cardiac arrest (Table
4).

   Seven RCTs
enrolling 932 patients provided data for the analysis. The ORs of death or
cardiac arrest were significantly decreased by roughly 50% in the posterior
pericardial drainage group

 

compared with controls: OR (95% CI): 0.47, P = 0.028; I2 = 0%.

        There were
11 deaths (1.18%) or cardiac arrests compared with 23 (2.53%), respectively, in
the posterior pericardial drainage and control groups.

 

Table 4: comparison between posterior pericardial
drainage (intervention) and control group for prevention of death or cardiac
arrest after heart surgery.DISCUSSION    In the present
systematic review and meta-analysis we attempted to analyze and evaluate the
potential beneficial value of posterior pericardial drainage after heart
surgery. The key finding was the high effectiveness of posterior pericardial
drainage in preventing cardiac tamponade as well as mortality without
jeopardizing safety.  Only
14 were usedPrimarily, the present meta-analysis included 16 RCTs and 2755 patients and evidently demonstrated
significantly reduced odds of death or cardiac arrest.      Statistically,
even though there were no differences for the total volume of chest tube drainage, more pleural
effusions (requiring intervention or not) were reported in the intervention
arm, nevertheless, this did not lead to a higher incidence of pulmonary complications when
compared to the control group.    Furthermore, delayed-onset pericardial
effusion after heart surgery may produce significant morbidity in
addition to management by traditional surgical techniques involving
resternotomy. The
pericardial ?uid collected in a gap in front of the heart usually is easily
drained via a chest drain; however, because pericardial adhesions are frequently
observed between the inferior and posterior surfaces of the heart and the
diaphragm, they may create an enclosed gap that makes drainage dif?cult (31). The use of our pericardiotomy
technique enables better drainage of the pericardial ?uid and prevents the
formation of effusion or tamponade.        Naturally, PP is performed as a longitudinal,
4-cm long incision parallel and posterior to the phrenic nerve, covering the
whole area from the left inferior pulmonary vein to the diaphragm(32). This allows unobstructed drainage of the blood and fluids
from the pericardium directly to the pleural space. PP is easy to perform
and it is cost-effective. Compared to  a
simple chest tube drainage, however, PP may not be entirely free from
intervention-related complications; and a potential risk of cardiac herniation(33).       These complications may be minimized
by performing a limited PP at the end of the procedure at a distance from the
bypass grafts.    Nevertheless,
it’s important to mention that Meta-analyses
of studies conducted so far are not conclusive regarding the prevention of
cardiac tamponade, and guidelines. Recommendations are still weak with regard
to routine posterior pericardial drainage.    Still, it’s
evident in the present study that PP’s true benefit in the reduction of  incidence of cardiac tamponade which in turn
reflects lower odds of mortality or cardiac arrest results.     Numerous mechanisms were proposed to
predispose to POAF. One of which is a hypothesis that a certain amount of
fluid/hematoma into the pericardium may represent a mechanical irritating
stimulus to the atria, whose function can be affected by external compression.

    To sum up, the
assessment of safety and effectiveness of PP study significantly justified
their  roles  in the reduction of the incidence of pericardial
effusion and, accordingly, reducing
the incidence of supraventricular arrhythmias in the postoperative period.  Arrythmias
were not assessed in this study CONCLUSION

Posterior
pericardial drainage has proven to be an easy , safe and effective technique
that significantly reduces not only the prevalence of early pericardial
effusion and related POAF but also delayed pericardial effusion and cardiac
tamponade. These benefits, in turn, translate into lower odds of AKI and
improved survival after heart surgery.  This
study did not look at AKI also POAF was not looked at and this is different from the conclusion
in the abstract.