The 2006 American College of Cardiology (ACC)/American Heart Association (AHA) guidelines for the treatment of valvular heart disease (VHD) were notable for the paucity (0.3%) of the recommendations supported by a level of evidence A—that is, evidence supported by two or more randomized controlled trials (RCTs).1 Although several RCTs have been published since then and the evidence level supporting the 2014 guidelines improved markedly,2 there are no RCTs and indeed only limited data-driving management decisions in mixed VHD. In a 230-page document, the current guideline devotes scarcely two pages to the topic. The following chapter will summarize some of the modest data that are available.
TRICUSPID REGURGITATION AND LEFT-SIDED VALVE DISEASE
Most tricuspid regurgitation (TR) is secondary to overload caused by left-sided heart disease or by lung disease. Causes of primary TR include blunt trauma such as might occur in a motor vehicle accident, direct trauma from errant myocardial biopsies, carcinoid syndrome (or use of drugs with serotonin similarities), rheumatic heart disease, infective endocarditis, and interference from transvalvular pacing electrodes.
The general rule for treating secondary TR is to optimize therapy for the primary cause. Thus, if left-sided heart failure has resulted in pulmonary hypertension with adverse effects on the right ventricle, treatment of heart failure will reduce pulmonary pressure and improve secondary TR. Or, if lung disease has created cor pulmonale, therapy to improve pulmonary function is apt. However, this rule may be inappropriate when secondary TR is caused by left-sided valve lesions. Although it has long been hoped that correction of the hemodynamic overload produced by mitral or aortic valve disease would improve secondary TR, the results are unpredictable, with TR sometimes improving, sometimes worsening, and sometimes even arising de novo following left-sided valve surgery.3,4,5,6,7,8 Although there is general agreement that severe TR, irrespective of its cause, should be addressed during surgery for left-sided disease, the approach to less than severe secondary TR is the subject of intense controversy. If leaving moderate TR uncorrected results in worsening rather than improvement in TR following successful left-sided surgery, the patient is then consigned either to the consequences of right-sided heart failure, despite the correction of the primary valve lesion, or to a second operation to address the residual TR, which has had an unusually variable and sometimes high mortality in reports of small series.3,9,10 The variable response of TR to correction of left-sided valve disease is in part related to the causes and effects of the left-sided disease and its correction. As noted in other chapters, if the left-sided disease is secondary mitral regurgitation, left ventricular (LV) dysfunction is almost surely present and is not addressed by mitral surgery, serving as a cause for persistently elevated left- and right-sided chamber pressures, perpetuating TR. Even if pulmonary pressure is reduced by left-sided surgery, ...