A 72-year-old female, with a prior history of degenerative joint disease and mild asthma, is admitted to the hospital with CHF. Three years ago she had a normal ECG and echo with an estimated EF of 60-65%. On this admission her ECG showed a first degree AV block (PR of 220-240) and a LBBB. Her echo showed a reduced EF of 30-35% with mild diastolic MR. A MPI showed no scar or ischemia. Troponin, routine viral titers and standard rheumatologic assays were all normal. She was placed on carvedilol, valsartan, spinonolactone and digoxin in optimized doses.
Over the next three months she had one hospitalization and one ER visit for CHF. She has had functional class II-III heart failure symptoms but no palpitations, syncope or documented ventricular arrhythmias. When she returned to you for follow-up after four months of therapy, while in a stable condition, her ECG showed a persistent and progressive first degree AV block (PR of 270-300) and a LBBB. Her echo continued to show a reduced EF of approximately 30-35% with now moderate diastolic MR and a slight increase in the degree of LV enlargement. She was referred for a cardiac cath and MRI. The cardiac cath showed no obstructive CAD (maximal 10-20% luminal irregularities) and moderate MR. The cardiac MRI showed no scar, moderate diastolic MR and an EF of 35-40%. A TDI showed marked intra-ventricular and inter-ventricular dyssynchrony.
When she returns to see you in follow-up what would you recommend?
Show Answer
The correct answer is: D. Referral for possible biventricular pacer (CRT-P) with reassessment of EF in 3-4 months and possible upgrade to a biventricular defibrillator (CRT-D) if the EF does not improve.
The patient has underlying conduction disease, which may have been exacerbated by the carvedilol. However it is unlikely that discontinuation of the carvedilol, even if the PR interval returned from the present level of 270-300 msec to the original range of 220-240 msec, would result in a subsequent significant improvement in the EF. Therefore option A (discontinuation of carvedilol), since carvedilol has a beneficial effect in patients with LV systolic dysfunction, is not likely to have a positive short-term or long-term positive impact on the patient’s EF and prognosis.1
The initial workup with negative viral titers, a normal rheumatological review and normal troponin argue against an acute viral and/or inflammatory myocarditis. The subsequent MRI provides additional evidence against a viral and/or inflammatory myocarditis. Endomyocardial biopsy has a variable and relatively low predictive accuracy, moderate false positive and false negative rates, limited sensitivity and specificity, significant interobserver interpretation variability and a defined procedural risk. Guidelines, published under the direction of the direction of the Heart Failure Society of America, recommend caution when considering an endomyocardial biopsy.2-5 Accordingly, a more aggressive workup for myocarditis (option B) is probably not warranted in this case.
Diastolic mitral regurgitation has been described as a secondary or functional finding in a number of patients with left ventricular systolic dysfunction.6-7 The exact mechanism is unknown but probably multifactorial. Dilation of the left ventricle and mitral annulus, geometric distortion of the valve and its subvalvular components, an imbalance between the opening and closing forces that impact the valve, a reduction in the maximal opening of the mitral leaflets during diastole, etc. have all been proposed as potential causes. Surgical and percutaneous correction of valvular components and cardiac resynchronization therapy (CRT) have both been shown to have a salutary effect on a number of functional and clinical endpoints in selected patients. However publications to date have derived from single center or small series studies. There is no prospective data to suggest that intervention on the mitral valve can improve outcomes in large populations of patients with diastolic MR and LV dysfunction. Accordingly an aggressive approach, such as this (option C), would not appear warranted.
Referral for a biventricular defibrillator (CRT-D) is a very reasonable option (option E). The patient has not responded to medical therapy and still has a reduced LVEF. By the echo-determined EF, the duration of the cardiomyopathy and the use of appropriate medical therapy the patient meets criteria for an ICD, as defined by the guidelines and by CMS reimbursement criteria.8-9 However, several concerns with this approach manifest. By MRI the EF is now in the range in which ICD implantation without further risk stratification may be problematic. In addition, the absence of an identifiable cause for the cardiomyopathy, the marked dyssynchcrony and the normal EF several years ago suggest that the cardiomyopathy may derive from the conduction disease (i.e. the first degree AV block and the LBBB) as opposed to the reverse. Theoretically eradication of these conduction defects might reverse the cardiomyopathy. There is data supporting conduction disease as a cause for cardiomyopathies in selected patients. There is also date suggesting that correction thereof may improve the LV function.10-11 However, the research in support thereof is limited to single center or small series studies.
A detailed discussion with the patient and her family took place in which all options were reviewed and discussed. She decided to proceed with a CRT-P (option D), hoping that her EF would improve. One year after CRT-P implantation her EF by echo was 45-50% and the diastolic MR was minimal. Her EF has remained in the 45-55% range over the past 5 years. Although one cannot state so with complete certainty, the evidence suggests, in this case, that the cardiomyopathy was a secondary phenomenon, deriving from the intrinsic conduction abnormality.
References
Packer M, Fowler MB, et al.; Effect of carvedilol on the morbidity of patients with severe chronic heart failure: results of the carvedilol prospective randomized cumulative survival (COPERNICUS) study. Circulation 2002;106:2194–9.
Karatolios K, Pankuweit S, Maisch B. Diagnosis and treatment of myocarditis: the role of endomyocardial biopsy. Curr Treat Options Cardiovasc Med 2007;9:473-81.
Cooper LT, Baughman KL, et al. The role of endomyocardial biopsy in the management of cardiovascular disease: a scientific statement from the American Heart Association, the American College of Cardiology, and the European Society of Cardiology. Circulation 2007;116:2216-33.
Lindenfeld J, Albert NM, et al. HFSA 2010 Comprehensive Heart Failure Practice Guideline. J Card Fail 2010;16:1-194.
Heart Failure Society Of America. Executive summary: HFSA 2006 Comprehensive Heart Failure Practice Guideline. J Card Fail 2006;12:10-38.
Faber L, Lamp B. Mitral valve regurgitation and left ventricular systolic dysfunction: corrective surgery or cardiac resynchronization therapy? Herzschrittmacherther Elektrophysiol 2008; 19 (Suppl 1):52-9.
Nof E, Glikson M, et al: Mechanism of diastolic mitral regurgitation in candidates for cardiac resynchronization therapy. Am J Cardiol 2006;97:1611-4.
Epstein AE, Dimarco JP, et al. ACC/AHA/HRS 2008 guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: executive summary. Heart Rhythm 2008;5:934-55.
Blanc JJ, Fatemi M, et al. Evaluation of left bundle branch block as a reversible cause of non-ischaemic dilated cardiomyopathy with severe heart failure. A new concept of left ventricular dyssynchrony-induced cardiomyopathy. Europace 2005; 2005:604-10.
Fujii B, Takami M. Normalization of left ventricular function following cardiac resynchronization therapy: left bundle branch block as a potential etiology of dilated cardiomyopathy. Circ J 2008;72:1030-3.
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