Key role of congestion in natural history of heart failure.

The natural course of heart failure with decreased and preserved systolic function is almost identical. The current concept of heart failure where decreased cardiac output plays the major role does not explain this similarity. We suggest a revised concept of heart failure where congestion plays the leading role. While congestion is almost invariably present in heart failure with normal and with reduced systolic function, the low output syndrome is only present in heart failure with reduced systolic function. The small difference in morbidity and mortality in favor of heart failure with preserved systolic function reflects the contribution of low output syndrome to the natural course of the disease. Congestion can result from low output or from multiple other conditions, but severity of congestion is the major determinant of progression of heart failure.