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The New England Journal of Medicine -- June 11, 1998 -- Volume 338, Number 24

Prolongation of the QT Interval and the Sudden Infant Death Syndrome

Peter John Schwartz, Marco Stramba-Badiale, Alessandro Segantini, Paola Austoni, Giuliano Bosi, Roberto Giorgetti, Fabio Grancini, Ernesto Diego Marni, Francesco Perticone, Dario Rosti, Patrizia Salice


Background. The sudden infant death syndrome (SIDS) is multifactorial in origin, but its causes remain unknown. We previously proposed that prolongation of the QT interval on the electrocardiogram, possibly resulting from a developmental abnormality in cardiac sympathetic innervation, may increase the risk of life-threatening ventricular arrhythmias and contribute to this devastating disorder. We prospectively tested this hypothesis.

Methods. Between 1976 and 1994, we recorded electrocardiograms on the third or fourth day of life in 34,442 newborns and followed them prospectively for one year. The QT interval was analyzed with and without correction for the heart rate.

Results. One-year follow-up data were available for 33,034 of the infants. There were 34 deaths, of which 24 were due to SIDS. The infants who died of SIDS had a longer corrected QT interval (QTc) than did the survivors (mean [±SD], 435±45 vs. 400±20 msec, P<0.01) and the infants who died from causes other than SIDS (393±24 msec, P<0.05). Moreover, 12 of the 24 SIDS victims but none of the other infants had a prolonged QTc (defined as a QTc greater than 440 msec). When the absolute QT interval was determined for similar cardiac-cycle lengths, it was found that 12 of the 24 infants who died of SIDS had a QT value exceeding the 97.5th percentile for the study group as a whole. The odds ratio for SIDS in infants with a prolonged QTc was 41.3 (95 percent confidence interval, 17.3 to 98.4).

Conclusions. Prolongation of the QT interval in the first week of life is strongly associated with SIDS. Neonatal electrocardiographic screening may permit the early identification of a substantial percentage of infants at risk for SIDS, and the institution of preventive measures may therefore be possible. (N Engl J Med 1998;338:1709-14.)

Source Information

From the Department of Cardiology, Policlinico San Matteo Istituto di Ricovero e Cura a Carattene Scientifico and the University of Pavia, Pavia (P.J.S.); Centro di Fisiologia Clinica e Ipertensione, University of Milan and Ospedale Maggiore Istituto di Ricovero e Cura a Carattene Scientifico, Milan (M.S.-B., A.S., F.G.); the Cardiology Department A. De Gasperis, Ospedale Niguarda Ca' Granda, Milan (P.A.); the Pediatrics Institute, University of Ferrara, Ferrara (G.B.); Ospedale Galmarini, Tradate (R.G.); the Department of Pediatrics, University of Pavia, Pavia (E.D.M.); the Department of Experimental and Clinical Cardiology G. Salvatore-Catanzaro, University of Reggio Calabria, Catanzaro (F.P.); and Ospedale Regina Elena, Milan (D.R., P.S.) -- all in Italy. Address reprint requests to Dr. Schwartz at the Department of Cardiology, Policlinico San Matteo IRCCS, Piazzale Golgi, 2, Pavia 27100, Italy.

Centers and investigators participating in the study are listed in the Appendix.


The following centers and investigators participated in the Multicenter Italian Study of Neonatal Electrocardiography and SIDS: University of Milan, Milan (coordinating center) -- P.J. Schwartz, M. Stramba-Badiale, A. Segantini, F. Grancini, P. Careddu, V. Carnelli, M. Facchini, M. Montemerlo, M. Frediani, S. Guffanti, M. Negrini, F. Palla, N. Porta, P. Rusinenti, and T. Varisco; Ospedale Regina Elena, Milan -- D. Rosti and P. Salice; Ospedale Galmarini, Tradate -- R. Giorgetti and G. Poggio; Ospedale Niguarda, Milan -- P. Austoni; University of Ferrara, Ferrara -- G. Bosi; University of Reggio Calabria, Catanzaro: F. Perticone; University of Rome, Rome -- S. Pelargonio; University of Pavia, Pavia -- E.D. Marni; Ospedale Regina Margherita, Turin -- M.G. Broveglio-Ferri; University of Florence, Florence -- G. Mainardi.

Copyright © 1998 by the Massachusetts Medical Society. All rights reserved.

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