Prognostic value of Tc-pyrophosphate uptake in patients with suspected transthyretin cardiac amyloidosis.

Background: This study aimed to evaluate the prognostic value of myocardial Tc-pyrophosphate (PYP) uptake in patients undergoing PYP imaging for suspected transthyretin cardiac amyloidosis (ATTR-CA).

Methods: A retrospective analysis of 301 consecutive patients who underwent PYP imaging for suspected ATTR-CA was performed. Myocardial PYP uptake was graded visually using the Perugini classification (grade 0-3) and quantified by the heart-to-contralateral lung uptake (H/CL) ratio. The primary outcome was combined cardiac death and documented fatal ventricular arrhythmias (ventricular fibrillation [VF] and sustained ventricular tachycardia [VT] lasting >30 seconds).

Results: Among the 301 patients, 90 had positive myocardial PYP uptake on SPECT. During a median follow-up of 668 days (interquartile range, 186-868 days), 36 patients died, including 13 cardiac deaths. Fatal ventricular arrhythmias were documented in 6 patients (2 aborted VF and 4 sustained VT). The primary outcome occurred in 8 of 211 (4%) patients with negative PYP SPECT and in 10 of 90 (11%) patients with positive PYP SPECT. Kaplan-Meier analyses showed a significantly higher incidence of the primary outcome in patients with positive PYP SPECT than in those without (P=.018). In contrast, all-cause mortality did not differ significantly between the two groups (P=.36). Multivariable Cox proportional hazards regression analyses showed that PYP SPECT positivity was an independent predictor of the primary outcome in patients with suspected ATTR-CA (adjusted hazard ratio: 2.86 [95% confidence interval: 1.10-7.41]; P =.031).

Conclusions: Significant myocardial PYP uptake was associated with an increased risk of adverse cardiac events in patients with suspected ATTR-CA.