Author + information
- ↵∗Heart Institute (InCor), University of São Paulo Medical School, Av. Dr. Enéas de Carvalho Aguiar, 44, Cerqueira César, São Paulo SP 05403-000, Brazil
We thank Drs. Rassi Jr. and Rassi for their interest in our paper titled “Long-Term Prognostic Value of Myocardial Fibrosis in Patients With Chagas Cardiomyopathy” (1).
The Rassi score (2) is a validated and readily available tool to stratify risk in patients with Chagas cardiomyopathy. However, as with so many other scores and diagnostic tests in multiple diseases and clinical scenarios, it has not yet been proven in prospective randomized clinical trials to determine patient treatment changes resulting in lower mortality rates.
Our study was not designed to demonstrate superiority of myocardial fibrosis (MF) evaluation by cardiac magnetic resonance (CMR) over the Rassi score in risk stratifying. Indeed, we believe that our findings add relevant information to the understanding of the pathophysiological processes involved in Chagas cardiomyopathy and its poor prognosis, and support the use of CMR in addition to the Rassi score.
In this sense, we feel that comparing the hazard ratios for the Rassi score against MF in an attempt to suggest its superiority is somewhat unfair because the Rassi score represents a collection of clinically relevant variables, including New York Heart Association functional class and left ventricular ejection fraction, whereas MF is a single variable. On a note of imprecise information in Letters to the Editor, MF’s hazard ratio (categorical variable for the combined endpoint) was actually superior to the Rassi score’s hazard ratio (1.943 vs. 1.205, Table 6 ), even though their 95% confidence interval overlapped. Moreover, in a univariate subgroup analysis, MF was able to detect those patients with arrhythmic events, whereas left ventricular ejection fraction and the Rassi score were not able to do so. These data raise the hypothesis that MF could be able to predict better implantable cardioverter-defibrillator–treatable events and, therefore, influence clinical decision in this regard.
A definitive answer to whether the presence or extension of MF significantly changes risk stratification in Rassi low- and intermediate-risk subgroups will require a new study. However, a subgroup analysis including only patients with a Rassi score in the low- and intermediate-risk ranges showed that MF using the cutoff of 12.3 g was able to clearly differentiate prognosis for combined events (Figure 1). Notably, the prevalence of patients with MF ≥12.3 g in the low- and intermediate-risk subgroups was 8.1% and 57.8% in our study (unpublished data, T. Senra, 2018), suggesting a potential role for MF to restratify risk in Chagas cardiomyopathy even in those with lower risk by the Rassi score. Moreover, for 72 patients with no events during follow-up, MF <12.3 g correctly restratified to low risk 20 patients classified as intermediate and high risk by the Rassi risk score and incorrectly restratified to high risk only 1 patient (non-event net reclassification index = 0.26).
On a final note, it is clear that the Rassi risk score is easy to use and gives a good prediction in patients who present with already evident and clinically relevant parameters known to be ominous in cardiomyopathy in general. However, MF is present long before this observable clinical phase appears and can provide strong event prediction and potentially reclassify and direct clinical management for patients in the low- and intermediate-risk ranges by the Rassi score. A combined new score possibly including the Rassi score parameters and MF by CMR could be a much more efficient one. To be tested.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2019 American College of Cardiology Foundation