Cardiac power index: staging heart failure for mechanical circulatory support

Cardiac power output has been shown to quantify cardiac reserve. Cardiac reserve is defined as the difference between basal and maximal cardiac performance. We compared cardiac power index to other commonly used hemodynamic parameters to validate its usefulness to stage heart failure patients and determine the optimal time for implantation of mechanical circulatory support. A retrospective study of twenty-eight heart failure patients implanted with mechanical circulatory support was analyzed at three levels of drug therapy. Subjects were further separated into two categories: survived versus deceased. Cardiac power index was the only statistically significant hemodynamic parameter that identified cardiac reserve (p<0.05) in this patient population. These results showed that a cardiac power index at or below 0.34 Watts/m(2) resulted in increased mortality rate, ninety days post-implantation.

Cardiac reserve was a determinant of post-device survival; therefore, these data suggest that device implantation should occur prior to the 0.34 Watts/m(2) threshold.