[The best of valvular heart disease in 2006].Arch Mal Coeur Vaiss. 2007 Jan; 100 Spec No 1:19-28.AM
In the field of valvular diseases, the year 2006 has been above all marked by the publication of new joint AHA/ACC guidelines. Besides, other publications included severe aortic stenosis, drug therapy in chronic aortic regurgitation, the indications for surgery in asymptomatic mitral regurgitation, as well as valve surgery in the elderly and mismatch severity after aortic valve replacement. In a series of 66 cases of aortic stenosis with poor LV function undergoing stress echocardiography, it has been shown that whether the absence of contractile reserve identifies a high-risk subgroup for aortic valve replacement (33% vs. 6%), this exam does not predict the functional prognosis and the post-operative LV function improvement. Hence, the absence of contractile reserve should not contra-indicate aortic valve replacement surgery, even though the prognosis is severe, since the natural prognosis is extremely severe. The question of aortic valve replacement in case of mild stenosis with the indication of CABG remains difficult. Taking into account the important mortality of redo surgery, a study was in favor of a systematic aortic valve replacement associated to CABG in patients <75 years who had a mean aortic gradient > 30 mmHg, a LVH and aortic valve calcifications. Old patients (>80 years) with severe aortic stenosis have a very severe natural prognosis, authorizing wide indications for aortic valve replacement, in the absence of important comorbidities. The use of vasodilators in severe chronic aortic regurgitation remains debated. In a randomized study comparing Nifedipine 40 mg vs. Enalapril 20 mm vs. placebo, it has been shown that the use of a vasodilator does not modify the time of valvular surgery at all. After a mean follow-up of 7 years, the rates of aortic valve replacement were identical in the 3 groups, and there wa no difference regarding the preoperative regurgitation volume, LV dimensions and mass, and LVEF. The timing for huge chronic and asymptomatic mitral regurgitation remains debated, even though the present trend is to prefer early surgery, due to the risk of sudden death. A new study evidenced the interest of clinical and echocardiographic surveillance on a prospective series of 129 consecutive asymptomatic patients with severe degenerative mitral regurgitation. The surgical indication was only based on the occurrence of symptoms, an echographic LV diameters increase, a LV dysfunction, the presence of pulmonary hypertension or atrial fibrillation. At 8 years, the overall mortality was at 91 + 3%, with a survival rate not statistically different from the expected rates; 35 patients have been operated. The 6-years and 8-years surgical indication-free survival were respectively at 65 +/- 5% and 55 +/- 6%, with a null operative mortality, and favorable data regarding post-operative survival, symptoms and LV function. The indication for surgical correction of mitral regurgitation in the elderly remains a difficult problem, due to the surgical risk. The Mayo Clinic team analyzed the evolution of 284 patients > 75 years operated for mitral regurgitation between 1980 and 1995, compared to younger subjects (65 - 74 years old, n=504, and <65 years, n=556). The age-adjusted 5-years survival was lower in the older patients, but the age-adjusted observed/estimated survival ratios were similar in the different age groups. The perioperative risk, significantly higher in the older patients (p<0.001) decreased systematically for all age ranges in the most recent periods (the 1980-83 period vs. 1992-95), from 27% to 5%, 21% to 4%, and 7% to 2% respectively in patients > 75 years, 65-74 years and <65 years. An age >75 years was an independent predictive factor for the surgical mortality. These data show that, despite the surgical risk, the surgical treatment of mitral regurgitation should be extended to the oldest patients. One of the most surprising information provided in the ACC/AHA guidelines is the necessity of adding a daily dose of 75 to 100 mg of aspirin systematically to VKA in patients with mechanical prosthetic valves or in those with a valvular bioprosthesis with one or several risk factors for thrombo-embolic events (AF, history of thromboembolic event, LV dysfunction, hypercoagulable state). This major recommendation (Class 1, level of evidence B) appears surprising, since it is not actually based on definite results issued from randomized studies using these doses of aspirin. According to these guidelines, this association not only reduces the risk of thrombo-embolic events in patients with valvular prosthesis, but also decreases the mortality related to other cardiovascular causes (especially coronary artery disease), with the cost of a minimal risk augmentation for hemorrhagic complications. The importance of pejorative prognosis of mismatch (defined as an inadequacy between the aortic orifice size and patient's body surface after aortic valve replacement) has been subject to several publications this year. The substantial increase of post-operative events and poor survival in patients with this mismatch imply adapted preventive strategies in terms of selection of diameters and type of aortic valvular prosthesis and associated aortic surgical techniques (such as annular enlargement or supra-annular position).