Lone T-Wave Alternans vs T-Wave Alternans Coupled with Mechanical Alternans Carry Different Risks

Background T-wave alternans (TWA) and mechanical alternans (MA) can be coupled. The goal of this study was to compare outcomes in patents with MA and TWA. Methods A prospective cohort study was conducted in the intensive cardiac care unit and enrolled 133 patients (59.6 ± 15.7 years; 65% men) admitted with acute heart failure (HF). Surface ECG and peripheral arterial blood pressure waveform via arterial line were recorded continuously. MA and TWA were measured by enhanced modified moving average method. All-cause death or heart transplant served as a combined primary endpoint. Results MA was observed in 28 patients (25%), whereas TWA was detected in 33 patients (33%). If present, MA was tightly coupled with TWA. Mitral flow deceleration time was shorter (127 ± 61 ms vs 172 ± 80 ms, P = .030), and left atrial systolic diameter was larger (5.1 ± 1.3 mm vs 4.4 ± 0.9 mm, P = .020) in patients with MA compared to those without. Mean TWA amplitude was larger in patients with both TWA and MA compared to patients with lone TWA (median 37 [interquartile range 26–61] µV vs 22 [21–23] µV, P = .045). After adjustment for New York Heart Association HF class, MA was associated with the primary endpoint (HR 2.3, 95% confidence interval 1.15–4.59, P = .018), whereas all lone TWA patients remained alive. Univariate Kaplan-Meier survival analysis showed the worst survival in patients with both MA and TWA at baseline, whereas patients without alternans had an intermediate probability of survival (Figure 1). All patients with lone TWA remained free from the primary endpoint. Conclusions HF patients with MA are characterized by restrictive diastolic dysfunction. The predictive value of TWA without simultaneous assessment of MA is inconclusive.