Studies of myocardial function in patients with hypophosphatemia have yielded conflicting results. Systolic time intervals were performed in 19 patients during and after the correction of hypophosphatemia; 11 had severe (0.9 ± 0.15 mg/dL) and eight had moderate (1.4 ± 0.11 mg/dL) hypophosphatemia. Controls were 14 patients with normal serum phosphorus levels. No patient with hypophosphatemia had clinical congestive heart failure. When hypophosphatemia was corrected, improvement in left ventricular performance was seen only in patients with severe hypophosphatemia (p < 0.001); in eight patients left ventricular performance was normal during hypophosphatemia but showed significant improvement with its correction (p < 0.01). Patients with moderate hypophosphatemia showed no significant change. Our results confirm the findings of O'Conner et al, whose study is the only previous one to demonstrate hypophosphatemia-induced myocardial depression in humans. Contradictory results from other studies may be explained by the inclusion of patients with moderate hypophosphatemia and failure to repeat measurements after the correction of hypophosphatemia. We conclude that reversible depression of myocardial performance is seen in hypophosphatemia only when it is severe. In some cases, normal left ventricular performance improves when hypophosphatemia is corrected.
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