Diagnostic accuracy of NT-proBNP ratio (BNP-R) for early diagnosis of tachycardia-mediated cardiomyopathy: a pilot study

Background When heart failure and tachycardia occur simultaneously, a useful diagnostic tool for early discrimination of patients with benign tachycardia-mediated cardiomyopathy (TMC) versus major structural heart disease (MSHD) is not available. Such a tool is required to prevent unnecessary and wearing diagnostics in patients with reversible TMC. Moreover, it could lead to early additional diagnostics and therapeutic approaches in patients with MSHD. Methods A total of 387 consecutive patients with supraventricular arrhythmia underwent assessment at a single center. Of these patients, 40 fulfilled the inclusion criteria with a resting heart rate C100 bpm and an impaired left ventricular ejection fraction \40%. In all patients, successful electrical cardioversion was performed. At baseline, day 1 and weekly for 4 weeks, levels of NT-proBNP and echocardiographic parameters were evaluated. An NT-proBNP ratio (BNP-R) was calculated as a quotient of baseline NT-proBNP/follow-up NT-proBNP. After 4 weeks, cardiac catheterization was performed to identify patients with a final diagnosis of TMC versus MSHD. Results Initial NT-proBNP concentrations were elevated and consecutively decreased after cardioversion in all patients. Multivariate regression and ROC analysis revealed that BNP-R discriminated between patients with TMC versus MSHD independent and superior to all other variables. The area under the ROC curve for BNP-R to detect TMC was 0.90 (95% CI 0.79–1.00; p\0.001) after 1 week and 0.995 (95% CI 0.99–1.00; p\0.0001) after 4 weeks. One week after cardioversion already, a BNP-R cutoff C2.3 was useful for TMC diagnosis indicated by an accuracy of 90%, sensitivity of 84% and specificity of 95%. Conclusion BNP-R was found to be highly accurate for the early diagnosis of TMC.