Comparison of the American College of Cardiology/American Heart Association and the European Society of Cardiology Guidelines for the Management of Patients With Valvular Heart Disease

Abstract: Background. The American College of Cardiology/American Heart Association (ACC/AHA) and the European Society of Cardiology (ESC) have developed guidelines to assist clinicians in making evidence-based decisions. This study compares the ACC/AHA and ESC guidelines for the management of patients with valvular heart disease (VHD). Methods. The current ACC/AHA and ESC guidelines for VHD, last updated in 2014 and 2012, respectively, were compared by class of recommendation (COR), level of evidence (LOE), and content. Results. The ACC/AHA and ESC VHD guidelines contain 229 and 85 recommendations, respectively. The COR distributions of the ACC/AHA and ESC VHD guidelines were 47.6% vs 44.7% class I [P=.65]; 46.3% vs 55.3% class II [P=.16]; and 6.1% vs 0.0% class III [P=.01], respectively. The LOE distributions were 3.1% vs 0.0% LOE A [P=.20]; 47.2% vs 10.6% LOE B [P<.001]; and 49.8% vs 89.4% LOE C [P<.001], respectively. The recommendation type distributions were 31.0% vs 2.4% diagnostic [P<.001]; 23.1% vs 16.5% medical therapy [P=.20]; and 45.9% vs 81.2% interventional/surgical recommendations [P<.001], respectively. The content of the guidelines was similar, with only minor differences in a few recommendations. Conclusions. The ACC/AHA VHD guidelines contain significantly more recommendations. The distribution of COR was similar, but the ACC/AHA guidelines included more LOE B recommendations and fewer LOE C recommendations, suggesting that the ACC/AHA guidelines place greater emphasis on published data than expert opinion. Overall, the ACC/AHA and ESC guidelines provide similar recommendations, suggesting consistency in practice; however, the relative paucity of LOE A recommendations highlights the need for additional research. 

J INVASIVE CARDIOL 2017;29(9):320-326. Epub 2017 April 15.

Key words: valvular heart disease, guidelines, quality, outcomes

Valvular heart disease (VHD) is common, with an estimated prevalence of 2.5%, which is expected to significantly increase with the aging of the population.¹ VHD treatment is rapidly evolving, with increasing use of transcatheter valve therapies. To set national and international standards for the management of patients with VHD, the American College of Cardiology/American Heart Association (ACC/AHA) and the European Society of Cardiology (ESC) published guidelines in 1998² and 2007³ with subsequent updates, most recently in 2014¹ and 2012,⁴ respectively. In the present study, we sought to compare the current American and European VHD guidelines.  

Methods

Source of materials. The ACC/AHA and ESC guidelines for the management of patients with VHD were downloaded from the ACC and ESC websites, respectively.^1,4 The most up-to-date versions of the guidelines were analyzed. The total number of recommendations, class of recommendation (COR), level of evidence (LOE) for each recommendation, and content of the guidelines were evaluated. Specifically, the type of guideline recommendation (diagnostic, medical therapy, interventional/surgical) was assessed for each recommendation, the references included in each document were compared one by one, and the similarities and differences of each recommendation were assessed.

Comparisons. The distributions of COR, LOE, type of recommendation, and number of citations in each guideline document were compared using the Chi-Square or Fisher’s exact tests. A P-value <.05 was considered statistically significant. All analyses were performed using JMP 12.0 (SAS Institute, Inc). 

Results

The ACC/AHA and ESC VHD guidelines included 229 and 85 recommendations, respectively. Stratification by COR, LOE, and type of recommendation is summarized in Table 1.

. The distribution of the COR was similar among ACC/AHA and ESC VHD guidelines (Figure 1). Very few recommendations had LOE A (3.1% vs 0.0%; P=.20). The ACC/AHA guidelines had significantly more LOE B recommendations (47.2% vs 10.6%; P<.001) and fewer LOE C recommendations (49.8% vs 89.4%; P<.001) (Figure 2). They also contained significantly more class I-B recommendations (22.3% vs 8.2%; P=.01) and class II-B recommendations (20.1% vs 2.4%; P<.001) and fewer class I-C recommendations (22.7% vs 36.5%; P=.01) and class II-C recommendations (26.2% vs 52.9%; P<.001) (Figure 3).

Type of recommendation. The ACC/AHA guidelines contained significantly more diagnostic recommendations than the ESC guidelines (31.0% vs 2.4%; P<.001) and proportionally fewer interventional/surgical recommendations, with the ESC guidelines consisting of primarily interventional/surgical recommendations (45.9% vs 81.2%; P<.001) (Figure 4).

Format. The different layout of the ACC/AHA and ESC VHD guidelines produces distinct reading experiences for the practicing clinician. The ACC/AHA guidelines are structured as recommendations followed by pertinent background information and related studies, producing a lengthy, but thoroughly detailed, document. In contrast, the ESC guidelines are presented as background information with brief recommendations set in tables outside the main text, enabling them to serve as a quick and practical reference. 

Stages. The ACC/AHA guidelines describe stages (A-D) for each condition within the VHD guidelines to classify the progression of disease from stage A (at risk but asymptomatic) to stage D (severely symptomatic). This is different than the ESC guidelines, which provide quantifiable cut-offs for what is considered severe disease, but subjective descriptions for mild-to-moderate disease severity. 

Scoring systems. The ACC/AHA guidelines refer to the New York Heart Association functional classification to describe stages of heart failure. Both guidelines recommend using scoring systems for estimating perioperative mortality, ie, the Society of Thoracic Surgeons (STS) and the EuroScore, acknowledging limitations within both systems. In particular, the ESC guidelines state that the logistic EuroScore overestimates operative mortality, especially as an indication for transcatheter aortic valve replacement (AVR), and recommend using the STS scoring system for a more accurate assessment. 

Citations. The ACC/AHA and ESC guidelines cite 939 and 241 publications, respectively (Figure 5). Of these, 101 were shared, corresponding to 10.8% of the ACC/AHA guidelines and 41.9% of the ESC guidelines. In the ACC/AHA guidelines, 64 of the cited publications were published after the online publication of the ESC guidelines on August 25, 2012. 

Aortic stenosis. The ACC/AHA and ESC guideline recommendations for diagnosing aortic stenosis (AS) significantly overlap.⁵ Due to the progressive nature of AS, both guidelines recommend periodic clinical evaluation of patients with severe asymptomatic AS; however, the basis for and frequency of these examinations vary between guidelines (Table 2). 

Both guidelines provide consistent recommendations for intervention in patients with AS. For patients who meet a surgical indication for AVR and have low surgical risk, both guidelines recommend surgical AVR. For patients with high surgical risk, the ACC/AHA and ESC guidelines recommend transcatheter AVR as a reasonable alternative. Moreover, in cases of patients with low-flow, low-gradient severe AS with normal left ventricular ejection fraction (LVEF), limited data exist regarding the advantages of intervention compared with medical management. For this patient subset, both guidelines recommend intervention when an evaluation suggests significant valve obstruction.

Aortic regurgitation. In patients with aortic regurgitation, symptoms are an important indication for AVR. In asymptomatic patients, the two guideline sets recommend slightly different left ventricular end-diastolic diameter (LVEDD) cut-offs: >65 mm (ACC/AHA) vs >70 mm (ESC). This recommendation is based on a study demonstrating increased risk of death, symptoms, and LV dysfunction among patients with LVEDD ≥70 mm (Table 2).⁶ 

Mitral stenosis. Both the ACC/AHA and ESC guidelines recommend long-term anticoagulation to prevent arterial embolization in patients with atrial fibrillation, a prior embolic event, or left atrial thrombus (Table 2). Yet, in patients with normal sinus rhythm, the ACC/AHA guidelines state that whether to administer long-term anticoagulation on the basis of left atrial enlargement or spontaneous contrast on transesophageal echocardiography is controversial, whereas the ESC guidelines recommend considering long-term anticoagulation in these cases (COR IIa; LOE C). 

As a result of the lack of evidence supporting general use of beta-blockers in patients with mitral stenosis (MS) and normal sinus rhythm, the ACC/AHA guidelines recommend considering a trial of beta-blocker therapy for patients whose symptoms worsen significantly with exercise.^7,8 The ESC guidelines state that beta-blockers or heart-rate regulating calcium-channel blockers could improve exercise tolerance. 

The indications for intervention in asymptomatic patients with mild MS differ slightly. The ACC/AHA guidelines state that percutaneous mitral balloon commissurotomy may be considered for patients with mild and asymptomatic MS in the case of new-onset atrial fibrillation. The ESC guidelines state that intervention should only be performed in patients with clinically significant MS (valve area ≤1.5 cm²).

Mitral regurgitation (primary and secondary). For treatment of primary mitral regurgitation (MR), both guidelines recommend similar cut-offs for mitral valve replacement (Table 2). The ACC/AHA guidelines recommend mitral valve surgery for patients with a left ventricular end-systolic diameter (LVESD) ≥40 mm, regardless of LV function. The ESC guidelines list the cut-off as ≥40 mm for patients with no LV dysfunction (LVEF >60%), but for patients with LV dysfunction (LVEF ≤60%), they indicate an LVESD cut-off of ≥45 mm. Furthermore, the ESC guidelines state that in asymptomatic patients with preserved LV function and flail leaflet, surgery is recommended when LVESD is ≥40 mm. Both guidelines reference a study demonstrating increased mortality with conservative management after mitral surgery for patients with LVESD ≥40 mm.⁹ 

The ACC/AHA and ESC guidelines recommend considering percutaneous edge-to-edge mitral valve repair in patients with severe symptomatic primary MR who are at high risk for surgery (ACC/AHA COR IIb, LOE B; ESC COR IIb, LOE C) based on the results of the EVEREST (Endovascular Valve Edge-to-Edge Repair Study) II trial. EVEREST II reported a procedural success rate of approximately 75% for percutaneous mitral valve repair with acceptable risk for complications.¹⁰ 

The decision whether to intervene in patients with secondary MR is controversial due to the lack of evidence showing that correction of secondary MR improves life expectancy or ameliorates symptoms. The ACC/AHA guidelines state that mitral valve surgery may be reasonable for patients with moderate secondary MR who are undergoing surgery for other indications (COR IIb; LOE C). 

Tricuspid regurgitation. Although tricuspid valve repair is preferred to replacement, the ACC/AHA and ESC guidelines recommend that valve replacement with bioprosthetic or mechanical valves may be considered. The ACC/AHA guidelines recommend basing the decision on the age of the patient, while the ESC guidelines recommend large bioprostheses over mechanical valves due to studies that have shown satisfactory durability of bioprostheses in the tricuspid position (Table 2).¹¹ 

Tricuspid stenosis. When considering bioprosthetic or mechanical valves for patients with tricuspid stenosis, the guidelines include recommendations similar to those for patients with tricuspid regurgitation. The ACC/AHA guidelines recommend that the decision be individualized, while the ESC guidelines favor bioprosthetic valves over mechanical valves in patients with tricuspid stenosis (Table 2).

Prosthetic valves. While the ACC/AHA guidelines recommend that bioprostheses are reasonable in patients >70 years old, the ESC guidelines provide more detail, recommending the use of a bioprosthesis in patients >65 years old in the aortic position and >70 years old in the mitral position (Table 2). In addition, to evaluate structural valve deterioration associated with bioprosthetic valves, the ACC/AHA guidelines suggest performing an annual transthoracic echocardiogram (TTE) after the first 10 years, unless a patient is at higher risk of valve deterioration. The ESC guidelines recommend an annual TTE after the first 5 years, or even earlier in younger patients. 

The ACC/AHA guidelines do not recommend one type of valve over another for pregnant women or women of childbearing age, suggesting a discussion of the risks and benefits of mechanical and bioprosthetic valves. The ESC guidelines recommend bioprosthetic valves for women contemplating pregnancy, despite the risk of rapid structural valve deterioration, as a result of the risks associated with anticoagulation required for mechanical valves. 

Discussion

The major findings of this study, which compared the ACC/AHA and ESC guidelines for the management of patients with VHD, are as follows: (1) the recommendations are very similar in the two guideline sets, with only minor differences; (2) the ACC/AHA guidelines contain an overall greater number of recommendations because they address more topics and include more diagnostic recommendations than the ESC guidelines; and (3) the ACC/AHA recommendations have a higher LOE distribution than the ESC guidelines, suggesting more emphasis on published data than expert opinion.

Number of recommendations. The larger number of ACC/AHA guideline recommendations may be attributed to several factors. First, the ACC/AHA guidelines address more conditions, such as bicuspid aortic valve and aortopathy, tricuspid stenosis, surgical considerations, and non-cardiac surgery (Table 3). The ESC refers to these topics within the text of the guidelines, without providing recommendations with COR and LOE. Moreover, the ESC guidelines do not address infective endocarditis, instead providing a separate set of guidelines.¹² The ESC also developed a separate set of guidelines for the management of cardiovascular diseases during pregnancy, a topic that is briefly addressed in the ESC VHD guidelines.¹³ Second, the ACC/AHA guidelines include significantly more recommendations pertaining to VHD diagnosis (Figure 4). Third, the ESC guidelines were published 2 years before the ACC/AHA guidelines, during a time with many developments in VHD management, particularly in transcatheter valve therapies. Fourth, the disparity in the number of recommendations reflects a stylistic difference between the two guideline sets – the ACC/AHA guidelines as a comprehensive document and the ESC guidelines as a pragmatic reference. 

Level of evidence. Despite the comparable content of the ACC/AHA and ESC guidelines and the similar distribution of COR, the distribution of LOE among the recommendations varied significantly. Like other cardiology guidelines, very few recommendations had LOE A evidence in both documents, highlighting the need for additional prospective, high-quality studies to address current gaps in knowledge (Figures 2 and 3). The ACC/AHA guidelines include more LOE B recommendations, and the ESC guidelines include more LOE C recommendations. An assessment of the citations of each document revealed that the ACC/AHA guidelines referenced almost four times as many publications as the ESC guidelines, potentially accounting for this disparity. Most of these references (875 out of 939) were published prior to the release of the 2012 ESC guidelines, and 101 of those references were included in the ESC guidelines. The ESC guidelines rely more heavily on expert or consensus opinion, case studies, and standard of care, while the ACC/AHA recommendations are written with a stronger emphasis on published data.

Study limitations. Our study has important limitations. We only examined the final published guidelines, and did not have information on the deliberations that went into the development of each document. The ACC/AHA guidelines were published 2 years after the ESC; hence, more published studies were available for inclusion. However, <10% of the references were published after the ESC guidelines.

Conclusion

Clinical guideline documents are critical for delivery of high-quality and evidence-based clinical care. Our analysis demonstrates that although the ACC/AHA guidelines for VHD are broader, addressing more areas than the ESC guidelines, they both provide very similar recommendations, suggesting concordant practice patterns on both continents. Most recommendations on both continents, however, are still based on lower levels of evidence, highlighting the need for additional research to improve the evidence required to guide medical practice. 

References

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11.    Chang BC, Lim SH, Yi G, et al. Long-term clinical results of tricuspid valve replacement. Ann Thorac Surg. 2006;81:1317-1323. 

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From ¹VA North Texas Healthcare System and UT Southwestern Medical Center, Dallas, Texas; ²Abbott Northwestern Hospital, Minneapolis Heart Institute, Minneapolis, Minnesota; ³Minneapolis VA Medical Center and University of Minnesota, Minneapolis, Minnesota; ⁴Baylor College of Medicine and Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas; and ⁵University of Massachusetts Medical School, Worcester, Massachusetts.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Sorajja discloses grants and personal fees from Abbott Vascular, Medtronic, and Boston Scientific; personal fees from Lake Regions Medical. Dr Garcia reports consulting fees from Medtronic. Dr Rangan discloses grants from Spectranetics and InfraRedx. Dr Banerjee reports grants from Gilead and the Medicines Company; consultant/speaker honoraria from Covidien and Medtronic; ownership in MDCare Global (spouse); and intellectual property in HygeiaTel. Dr Brilakis reports personal fees from Abbott Vascular, Asahi Intecc, Elsevier, GE Healthcare, and Cardinal Health; grants from Boston Scientific and InfraRedx; spouse is an employee of Medtronic. The remaining authors report no conflicts of interest regarding the content herein. 

Manuscript submitted October 10, 2016; final version accepted November 30, 2016.

Address for correspondence: Emmanouil S. Brilakis, MD, PhD, Minneapolis Heart Institute, 920 E. 28th Street #300, Minneapolis, MN 55407. Email: esbrilakis@gmail.com