Short VT episodes after NSTE ACS linked to increased SCD risk
MedWire News: Nonsustained ventricular tachycardia (VT) episodes as short as 4 beats in duration within 48 hours of admission may increase the 1-year risk for sudden cardiac death (SCD) in patients admitted for non-ST-elevation acute coronary syndrome (NSTE ACS), a US study reports.
"We also found that episodes of VT lasting at least 8 beats that occurred within 48 hours of admission were not associated with SCD, whereas those that occurred later significantly increased the risk for SCD," say Benjamin Scirica (Brigham and Women's Hospital, Boston, Massachusetts) and colleagues.
"The results of our study support the use of extended continuous electrocardiograph (cECG) monitoring beyond 48 hours after admission... to identify patients at highest risk for arrhythmic death," they add.
In the study, patients hospitalized with NSTE ACS (n=6345) were monitored by cECG for the first 7 days after admission.
cECG results showed that 56.4% (n=3581) of the patients had at least one VT episode of at least 3 consecutive beats.
In all, 121 cases of SCD occurred during a 1-year follow-up period.
After adjustment for baseline characteristics and ejection fraction, no increase in SCD risk was found among the patients who had 3-beat VT episodes (n=1978) compared with those with no VT episodes (n=2764), at 1.4% versus 1.2%. However, patients with VT episodes lasting 4-7 beats (n=1172) had a higher SCD rate than those with no VT episodes, at 2.9% (p<0.001), reflecting a 2.3-fold greater risk.
In patients with VT episodes lasting for at least 8 beats, SCD rate increased by 4.3%, with a 2.8-fold increase in risk for SCD compared with those with no VT episodes (p=0.001).
The association between VT and SCD risk in these patients appeared to vary according to timing of the arrhythmia, however. In patients with a VT episode of 8 or more beats within 24-48 hours after admission, SCD risk was not significantly different to that of the patients who had no VT episodes.
But when VT lasting at least 8 beats occurred more than 48 hours after admission, a 2.9-fold increase in SCD risk was found (p=0.001).
Reporting their findings in the journal Circulation, the researchers say that the findings are "notable given that current ACS guidelines do not place great clinical significance on episodes of nonsustained VT."
In a related editorial, Kristen Patton (University of Washington, Seattle, USA) agreed that there is a "need to better identify those at highest risk, even within subpopulations in jeopardy of SCD."
She concluded: "Scirica and colleagues are to be congratulated for shedding light on this difficult puzzle. Future challenges will be to use these data to investigate the potential mechanisms of these associations."
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By Lauretta Ihonor