Isosorbide dinitrate and exercise performance in patients with congestive heart failure

Nitrates are widely used for the management of congestive heart failure (CHF), as well as angina pectoris. In both situations, nitrates significantly increase exercise capacity. The mechanism of this beneficial effect is unclear, especially in CHF. Isosorbide dinitrate reduces pulmonary capillary wedge pressure (PCWP) after a first dose. The improvement in exercise capacity is not apparent in the short term but is evident after long-term nitrate administration. Nitrates do not affect hemodynamics at maximal exercise but do reduce PCWP during submaximal exercise in patients with CHF. This observation, in addition to increased oxygen extraction at peak exercise during nitrate administration, suggests a "training like" peripheral effect of nitrates in CHF. Lowering of PCWP by nitrates may be important, since vasodilators that do not reduce PCWP also do not improve exercise capacity in CHF. How PCWP influences exercise performance in CHF is unknown, but the mechanism may relate to effects of PCWP on pulmonary hemodynamics more than on ventilation and blood oxygenation.