Myocardial infarction and baroreflex sensitivity. Clinical studies.
Based on solid experimental evidence the concept has emerged that analysis of autonomic reflexes, and specifically of baroreceptive reflexes, might contribute to the identification of high risk subgroups in the post myocardial infarction phase. Accordingly, we brought this concept to clinical fruition and have performed the first clinical study to investigate the potential prognostic value of baroreflex sensitivity. The present article reviews those clinical results which indicate an almost 15 times greater risk for cardiac mortality among the patients with depressed baroreflex sensitivity. Baroreflex sensitivity has also been correlated with heart rate variability and it was found that the degree of correlation is relatively weak and such that it is not possible to predict one measure from the other. Thus, these two autonomic markers are not redundant. Among the various possibilities to induce favorable alterations in the autonomic balance, our group has selected and analyzed exercise training and the chronic administration of beta-blocking agents. Exercise training, examined in a case-control study involving 70 patients, was found to increase baroreflex sensitivity by 30%. Beta-blockers were found to augment baroreflex sensitivity in 40% of the patients tested. As a logical evolution of these studies we have initiated a large prospective collaborative study destined to enroll 1200 post myocardial infarction patients and to assess the prognostic value of baroreflex sensitivity, of heart rate variability, and of traditional markers such as left ventricular ejection fraction and late potentials.
La Rovere
M T
MT
Divisione di Cardiologia, IRCCS, Fondazione Clinica del Lavoro, Pavia.
Mortara
A
A
Specchia
G
G
Schwartz
P J
PJ
D002986:Clinical Trials as Topic; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D015337:Multicenter Studies as Topic; D009203:Myocardial Infarction / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy; D011311:Pressoreceptors / Q000503:physiopathology*; D011379:Prognosis; D011446:Prospective Studies; D012021:Reflex, Abnormal / Q000502:physiology*; D012307:Risk Factors