Zusammenfassung
Ziel: Die beiden Ultraschallparameter Intima-Media-Dicke (IMT) in der Arteria carotis communis und der kürzlich etablierte Widerstandsindex (RI) in der Arteria carotis interna korrelieren mit dem Ausmaß der Atheriosklerose und sind Prädiktoren für kardiovaskuläre Morbidität und Mortalität. Bezüglich Progression und Langzeitprognose existieren für RI keine und für IMT nur sehr limitierte Daten. Material und Methoden: 145 Patienten mit mindestens einem kardiovaskulären Risikofaktor oder klinisch manifester Atheriosklerose wurden eingeschlossen. Bei Studienbeginn sowie nach 36 und 74 Monaten wurden IMT und RI duplexsonografisch bestimmt und das Auftreten von kardiovaskulären Ereignissen (kardiovaskulärer Tod, Schlaganfall, Herzinfarkt) im Längsverlauf erfasst. Ergebnisse: Die Log-rank-Analyse zeigte eine kontinuierliche Zunahme kardiovaskulärer Ereignisse bei steigendem RI- (p = 0.006) und IMT- (p = 0.011) Werten. Die IMT-Zunahme war in Patienten mit niedrigem SMART-Score (≤ 7 Punkte; klinisch einer geringen atherosklerotischen Vorbelastung entsprechend) im Vergleich zu Patienten mit hohem SMART-Score (> 7 Punkte) signifikant niedriger (32 ± 83 µm versus 95 ± 125 µm; p < 0.002). Bei Patienten mit kardiovaskulärem Ereignis zeigte sich mit 141 ± 105 µm pro Jahr die höchste Progressionsrate, während die durchschnittliche Progression bei Patienten ohne Ereignis 54 ± 111 µm betrug (p < 0.001). In keiner der Patientengruppen konnte eine RI-Progression über die 6 Jahre nachgewiesen werden (Patienten mit niedrigem versus hohem SMART-Score 0.00 ± 0.06 versus 0.00 ± 0.04; p = n. s.; Patienten mit versus ohne kardiovaskulärem Ereignis 0.00 ± 0.05 versus 0.01 ± 0.03; p = n. s.). Schlussfolgerung: Unsere Ergebnisse bestätigen den mit IMT vergleichbaren, prognostischen Wert des RI für kardiovaskuläre Ereignisse im Langzeitverlauf. Die IMT nimmt über 6 Jahre signifikant zu, besonders ausgeprägt bei Patienten, die im Verlauf ein kardiovaskuläres Ereignis erleiden. Im Gegensatz dazu konnte für RI keine Veränderung der Ausgangswerte nach 6 Jahren nachgewiesen werden. Obwohl zurzeit nicht ganz klar ist, ob und wie Medikamente den RI beeinflussen, scheint der Parameter für Verlaufsuntersuchungen offensichtlich nicht geeignet.
Abstract
Purpose: Intima-media thickness (IMT) of the common carotid artery and the resistive index (RI) of the internal carotid artery correlate with the degree of atherosclerosis and are predictors of cardiovascular morbidity and mortality. Limited or no data are available about long-term predictive values and the progression of the two markers themselves. Materials and Methods: 145 patients with at least one cardiovascular risk factor or clinically manifest atherosclerosis were included. At enrollment and after 36 and 74 months, duplex sonographic measurements of IMT CCA and RI ICA were performed. During follow-up, the occurrence of cardiovascular events (cardiovascular death, myocardial infarction, stroke) was assessed. Results: At baseline, IMT was 0.79 ± 0.16 mm and RI 0.66 ± 0.08. Log-rank analysis showed a continuous increase in the risk of a cardiovascular event with an increasing range of IMT (p = 0.011) and RI (p = 0.006). IMT progression in patients with low versus high atherosclerotic burden (as defined by SMART score ≤7 points and > 7 points) differs significantly (32 ± 83 µm versus 95 ± 125 µm; p < 0.002). IMT progression was even more pronounced in patients suffering a cardiovascular event (141 ± 105 µm versus 54 ± 111 µm; p < 0.001). No significant RI ICA progression could be detected during follow-up in any group (patients with low vs. high atherosclerotic burden 0.00 ± 0.06 versus 0.00 ± 0.04; p = n. s.; patients with vs. without cardiovascular event 0.00 ± 0.05 versus 0.01 ± 0.03; p = n. s.). Conclusion: Our results confirm the predictive value for cardiovascular events of RI and IMT in long-term follow-up. In contrast to RI, IMT increases over six years, above all in patients suffering a cardiovascular event. The results suggest that IMT is suitable for cardiovascular risk prediction as well as for progression measurements, while RI cannot be recommended for progression measurements. The effect of drug therapy on RI needs further clarification.
Key words
carotid arteries - arteriosclerosis - outcomes analysis - resistive index - intima media thickness
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PD Dr. Beat Frauchiger
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