Early Reperfusion in Acute MI Affects V-Tachycardia Characteristics
Last Updated: 2010-05-17 11:04:08 -0400 (Reuters Health)
NEW YORK (Reuters Health) - Patterns of ventricular tachycardia (VT) differ years later between patients who had early reperfusion of acute myocardial infarction (AMI) and those who didn't, Dutch researchers say.
Their new study, appearing in the May 4th issue of Circulation, finds that reperfusion, the standard therapy for AMI, is associated with less dense and less confluent electroanatomic scars, which are linked to faster spontaneous and inducible VTs.
"Reperfusion therapy during acute myocardial infarction results in myocardial salvage and improved ventricular function, but may also influence the arrhythmogenic substrate for VT," Dr. Katja Zeppenfeld, of Leiden University Medical Center, and colleagues write.
To assess the impact of reperfusion on the substrate and on VT characteristics late after acute myocardial infarction, the researchers compared results of electroanatomic voltage maps with infarct histology. A total of 36 patients (mean age 63 years, 32 men) referred for treatment of VT 13 years after acute myocardial infarction were included in the study. Of these, 14 had undergone acute reperfusion therapy and 22 were nonreperfused.
Overall, 27 patients were treated by radiofrequency catheter ablation. Ten patients, including six nonreperfused patients, were treated by ventricular restoration with intraoperative cryoablation in nine. Biopsies were obtained from the removed central part of the left ventricular scar during surgery.
In their paper, the researchers report that the VT cycle length of spontaneous VTs was significantly shorter in patients who underwent reperfusion than in those who did not (299 versus 378 ms; p = 0.01). Reperfused patients also had significantly shorter mean cycle length of induced VTs compared to nonreperfused subjects (270 versus 362 ms; p = 0.001).
"Fast VTs with a cycle length <250 ms were inducible in 71% of the reperfused patients compared with 23% of the nonreperfused patients (p = 0.003)," the researchers explain. "After exclusion of patients on amiodarone during EPS, the induced VT cycle length remained significantly shorter in reperfused patients (254 versus 334 ms; p = 0.006)."
A patchy scar pattern was found in 10 reperfused patients (71%), compared to only 3 nonreperfused patients (14%) (p = 0.001). Patients who underwent reperfusion had a significantly smaller percentage of dense scar compared to nonreperfused patients (24% versus 45%, respectively; p = 0.002).
Histological assessment was carried out in 10 patients undergoing a surgical intervention. Thick layers of surviving myocardium were revealed in 3 of 4 reperfused patients but in none of the nonreperfused patients.
Circulation 2010;121:1887-1895.
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