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Cardiac general: Shahzad Gull Raja and Naveed Fida Should angiotensin converting enzyme inhibitors/angiotensin II receptor antagonists be omitted before cardiac surgery to avoid postoperative vasodilation? Interactive CardioVascular and Thoracic Surgery published on Feb 13, 2008 as doi:10.1510/icvts.2007.174698 [Abstract] [Journal Format PDF]

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eResponse: ACE inhibitors as antifibrotic agents in atrial fibrillation: potential relevance in cardiac surgery

Shahzad G. Raja, Hill End Road, Harefield, UB9 6JH, Middlesex, United Kingdom   (20 March 2008)

eComment. ACE inhibitors as antifibrotic agents in atrial fibrillation: potential relevance in cardiac surgery

Karsten Knobloch, Andreas Gohritz, Marcus Spies, Peter M. Vogt   (6 March 2008)

eResponse: ACE inhibitors as antifibrotic agents in atrial fibrillation: potential relevance in cardiac surgery 20 March 2008
Shahzad G. Raja Department of Cardiac Surgery, Harefield Hospital, Hill End Road, Harefield, UB9 6JH, Middlesex, UK, Hill End Road, Harefield, UB9 6JH, Middlesex, United Kingdom drrajashahzad{at}hotmail.com Shahzad G. Raja, et al.	Interactive CardioVascular and Thoracic Surgery 2008, doi:10.1510/icvts.2007.174698A1 © 2008 European Association of Cardio-Thoracic Surgery Knobloch et al. have raised an interesting issue related to our BET [1] regarding omission of angiotensin converting enzyme inhibitors (ACEIs)/angiotensin II receptor antagonists (ARBs) before cardiac surgery. They highlight the potential impact of omission of ACEIs or ARBs on increased incidence of postoperative atrial fibrillation (POAF) after cardiac surgery. There is no doubt that increasing evidence is emerging to suggest that ACEIs or ARBs have the potential to prevent POAF, possibly due to their ability to decrease left atrial stretching (secondary to afterload reduction and stroke volume increases), preserve serum potassium concentrations or reduce pathogenic atrial remodelling [2,3]. However, it is important to understand that despite the publication of several meta- analyses [3,4], none of which includes cardiac surgery patients, the evidence for this potential benefit of ACEIs or ARBs for cardiac surgical patients is extremely weak. To date the only significant study by White et al. [5] failed to show a statistically significant association between the preoperative ACEI or ARB use and reduction in the odds of developing POAF. The results of this study are relevant as it was a prospective cohort evaluation of the 338 patients undergoing coronary artery bypass grafting and/or valvular surgery from the AFIST II and III randomized controlled trials (RCTs). Failure of White et al.[5] to replicate the results reported by the various other RCTs in non-cardiac surgical patients is perhaps due to the fact that population of cardiac surgery patients already has a high background utilization of both beta-blockers and prophylactic amiodarone, both of which are highly efficacious drugs in preventing POAF following cardiac surgery. Whether, an ACEI or ARB when administered alone would exert a larger or statistically significant effect is not known. Hence, the final part of the concluding statement of Knobloch et al. assumes more importance relative to the rest of their comment. There is no doubt that an RCT recruiting approximately 600 subjects, as suggested by White et al.[5] after conducting a post-hoc sample size calculation (á = 0.05; â = 0.20), is urgently needed to discern if ACEIs or ARBs truly impact POAF. References [1] Raja SG, Fida N. Should angiotensin converting enzyme inhibitors/angiotensin II receptor antagonists be omitted before cardiac surgery to avoid postoperative vasodilation? Interact Cardiovasc Thorac Surg. doi:10.1510/icvts.2007.174698. [2] Lally JA, Gnall EM, Seltzer J, Kowey PR. Non-antiarrhythmic drugs in atrial fibrillation: a review of non-antiarrhythmic agents in prevention of atrial fibrillation. J Cardiovasc Electrophysiol 2007;18:1222-8. [3] Jibrini MB, Molnar J, Arora RR. Prevention of atrial fibrillation by way of abrogation of the renin-angiotensin system: a systematic review and meta-analysis. Am J Ther 2008;15:36-43. [4] Anand K, Mooss AN, Hee TT, Mohiuddin SM. Meta-analysis: inhibition of renin-angiotensin system prevents new-onset atrial fibrillation. Am Heart J 2006;152:217-22. [5] White CM, Kluger J, Lertsburapa K, Faheem O, Coleman CI. Effect of preoperative angiotensin converting enzyme inhibitor or angiotensin receptor blocker use on the frequency of atrial fibrillation after cardiac surgery: a cohort study from the atrial fibrillation suppression trials II and III. Eur J Cardiothorac Surg 2007;31:817-20.
eComment. ACE inhibitors as antifibrotic agents in atrial fibrillation: potential relevance in cardiac surgery 6 March 2008
Karsten Knobloch Plastic, Hand and Reconstructive Surgery, Hannover Medical School, Hannover 30625, Germany, Andreas Gohritz, Marcus Spies, Peter M. Vogt kknobi{at}yahoo.com Karsten Knobloch, et al.	Interactive CardioVascular and Thoracic Surgery 2008, doi:10.1510/icvts.2007.174698A © 2008 European Association of Cardio-Thoracic Surgery Regarding the omission of ACE inhibitors or angiotensin II receptor antagonists before cardiac surgery [1] one should consider the potential beneficial effect of ACE inhibitors as an antifibrotic agent. Postoperative atrial fibrillation (POAF) complicates up to 8% of all noncardiac surgeries, between 3% and 30% of noncardiac thoracic surgeries, and between 16% and 46% of cardiac surgeries. POAF has been associated with increased morbidity, mortality, and longer, more costly hospital stays [2]. Given the fact that atrial fibrillation is the most frequent complication following cardiac surgery, recent studies have been reported that ACE inhibitors and angiotensin II receptor blockers are emerging drugs for the prevention of atrial fibrillation by modification of the renin-angiotensin-aldosterone system (RAAS) [3]. A meta-analysis of 11 randomized, controlled, parallel-design clinical trials evaluating effect of ACEIs or ARBs on the development of AF revealed that treatment with ACEIs or ARBs reduced the relative risk (RR) of AF in patients with hypertension by 23% and by 11% in patients after myocardial infarction. Reduction in AF was greatest in patients after electrical cardioversion and in patients with heart failure. Overall, inhibition of the RAAS reduced the RR of AF by 19% (RR 0.810, P < 0.001, 95% CI 0.759-0.865). However, the effect of ACE inhibitors/angiotensin II receptor blockers on the postoperative rate of atrial fibrillation is undetermined as of yet. The combination of a renin angiotensin system inhibitors (RAS-I) and bepridil might be even superior for the maintenance of sinus rhythm after conversion from persistent atrial fibrillation [4]. Based on these reports the omission of ACE inhibitors or angiotensin II receptor antagonists before cardiac surgery might have an effect on the postoperative rate of atrial fibrillation, which has to be determined in further perspective trials. References [1] Raja SG, Fida N. Should angiotension converting enzyme inhibitors/angiotensin II receptor antagonists be omitted before cardiac surgery to avoid postoperative vasodilatation? Interact Cardiovasc Thorac Surg, doi:10.1510/icvts.2007.174698. [2] Mayson SE, Greenspon AJ, Adams S, Decaro MV, Sheth M, Weitz HH, Whellan DJ. The changing face of postoperative atrial fibrillation prevention: a review of current medical therapy. Cardiol Rev 2007;15:231-41. [3] Jibrini MB, Molnar J, Arora RR. Prevetion of atrial fibrillation by way of abrogation of the renin-angiotensin system: a systematic review and meta-analysis. Am J Ther 2008;15:36-43. [4] Kawamura M, Ito H, Onuki T, Miyoshi F, Minoura Y, Asano T, Tanno K, Kobayashi Y. Combination therapy of renin angiotensin system inhibitors and bepridil is useful for maintaining sinus rhythm in patients with atrial fibrillation. J Cardiol 2007;50:343-50.