Mechanical alternans is associated with mortality in acute hospitalized heart failure: prospective mechanical alternans study (MAS)

Abstract

Background: Acute hospitalized heart failure (AHHF) is associated with 40% to 50% risk of death or rehospitalization within 6 months after discharge. Timely (before hospital discharge) risk stratification of patients with AHHF is crucial. We hypothesized that mechanical alternans (MA) and T-wave alternans (TWA) are associated with postdischarge outcomes in patients with AHHF.

Methods and results: 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 AHHF. Surface ECG and peripheral arterial blood pressure waveform via arterial line were recorded continuously during the intensive cardiac care unit stay. MA and TWA were measured by enhanced modified moving average method. All-cause death or heart transplant served as a combined primary end point. MA was observed in 28 patients (25%), whereas TWA was detected in 33 patients (33%). If present, MA was tightly coupled with TWA. Mean TWA amplitude was larger in patients with both TWA and MA when compared with patients with lone TWA (median, 37 [interquartile range, 26-61] versus 22 [21-23] μV; P=0.045). After a median of 10-month postdischarge, 42 (38%) patients died and 2 had heart transplants. MA was associated with the primary end point in univariable Cox model (hazard ratio, 1.84; 95% confidence interval, 1.00-3.40; P=0.05) and after adjustment for left ventricular ejection fraction, New York Heart Association HF class, and implanted implantable cardioverter defibrillator/cardiac resynchronization therapy defibrillator (hazard ratio, 2.12 95% confidence interval, 1.13-3.98; P=0.020). TWA without consideration of simultaneous MA was not significantly associated with primary end point (hazard ratio, 1.42; 95% confidence interval, 0.77-2.64; P=0.260).

Conclusions: MA is independently associated with outcomes in AHHF.

Clinical trial registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01557465.

Keywords: alternans; heart failure; mortality.

Figures

Figure 1:

Illustration of the method of (A) TWA, and (B) MA measurements by modified moving average. Lower panel shows averaged Odd and Even beats. Alternans are marked by arrows. STT=ST-T ECG segment. MMA=modified moving average method. CM=correlation method. MA=mechanical alternans.

Figure 2:

A. Representative example of MA in study participant MA074, African-American man, 41y, non-ischemic familial dilated cardiomyopathy, LVEF 15%, NYHA class III. Admitted after VF cardiac arrest. TWA 29 μV. MA 1mmHg. Alive. B. Representative example of detected TWA and MA events during 1h 45 min in study participant MA016, African-American woman, 88y, ischemic cardiomyopathy, LVEF 40%. Admitted due to acute decompensated HF.TWA 11 μV, MA 4.5 mmHg. Died. An upper tracing shows heart rate averaged during every 15-sec epoch.

Figure 3:

Kaplan‐Meier curves for the probabilities of the primary endpoint (all‐cause death or heart transplant) in patients with and without (A) MA, (B) TWA, (C) MA and TWA.