Author + information
- Ashrith Guha, MD, MPH∗ ( and )
- Jerry Estep, MD
- ↵∗Houston Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, 6550 Fannin, Smith Tower, Suite 1901, Houston, Texas 77030
We read with interest the paper by Burkoff et al. (1) proposing mechanical assist solution for heart failure with preserved ejection fraction (HFpEF). Treatment of HFpEF is particularly difficult due to multiple cardiac and extra cardiac influences on symptomatology and disease process (2). The multifaceted nature of this problem also makes patient selection for mechanical assist devices challenging. Although there have been proposals to classify HFpEF into different phenotypes for targeted therapy, a mechanical solution is very attractive as it will address the central hemodynamic abnormality of left atrial hypertension and dysfunction which in turn may reduce pulmonary hypertension, autonomic dysfunction, and impaired ventriculo-arterial uncoupling seen in HFpEF (2).
In a simulated model of left atrial cannulation, the investigators describe a simulated left atrial model of unloading which assumes a constant end systolic pressure volume relationship in the left atrium. Whereas this is true for the left ventricle in HFpEF, it is not clear that unloaded left atrium would follow that paradigm. We know from patients with left ventricular assist devices that left atrial size improves with unloading; however, studies evaluating left atrial function after left ventricular assist device implantation are lacking. It is possible the atrium attains complete functional recovery like it does after mitral valve surgery and maze procedure for atrial fibrillation. Recovery of left atrial function will change the end systolic pressure volume relationship as it does with complete left ventricular recovery. This assumption is different from that made by the investigators. In our experience with temporary support with left atrial cannulation (TandemHeart, CardiacAssist, Inc., Pittsburgh, Pennsylvania), we have observed that smaller left atrial size leads to suction events and thrombotic complications in these patients. We believe return of native atrial function could contribute to these adverse events.
The investigators also propose INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) − like classification for patients with HFpEF. The investigators acknowledge that it is difficult to correlate symptoms and functional status with hemodynamic compromise because of large contributions of extra cardiac manifestations such as anemia, obesity, sleep apnea, and chronic kidney disease to the symptomatology in HFpEF. Also, prognostication predominantly on the basis of functional status is not well established in common forms of HFpEF.
The addition of objective parameters could be considered while creating an INTERMACS-like classification for HFpEF. Two objective parameters that may improve risk stratification in this population are the degree of left atrial dysfunction and severity of pulmonary hypertension. Multiple studies in different cohorts of patients have found that left atrial emptying function and active booster function, but not commonly used left atrial volume index, were independent predictors of mortality and morbidity (3). Recently in a CMR-based study LA-EF was shown to be predictive of event free survival in patients with heart failure. We believe addition of left atrial parameters will aid in better selection of patients for such a pump as they act as valuable surrogates of the primary driver of hemodynamic abnormality and morbidity in HFpEF (4).
Secondly the presence of pulmonary hypertension has been shown to be consistently associated with worse prognosis in patients with HFpEF. Including pulmonary hypertension would help further risk stratify these patients and provide an objective measure which is not included in traditional risk stratification models of heart failure (5). Finally, we would like to congratulate the authors in providing this conceptual frame work and we hope application of these concepts translates into a clinical trial to address this vexing problem.
Please note: Dr. Estep is a consultant to Thoratec Corporation, and Maquet. Dr. Guha has reported that he has no relationships relevant to the contents of this paper to disclose.
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