Key result
Patients with a history of VT/VF after remote anterior myocardial infarction had significantly steeper QT/RR slopes in the modified V5 lead compared to those without (0.233 vs 0.150).
Why the study?
Does repolarization dynamicity differ between post-anterior MI patients with and without a history of VT/VF?
Cohort (n=88)
No
Does repolarization dynamicity differ between post-anterior MI patients with and without a history of VT/VF?
Absolute Event Rate: 0.233% vs 0.15%
p-value: p=0.0001
Post-anterior MI patients with a history of VT/VF exhibit steeper repolarization dynamicity, particularly in the V5 lead, suggesting its potential utility as a marker for arrhythmic risk.
Hypothesis-generating for QT/RR slope as arrhythmic marker post-anterior MI; prospective validation needed before clinical use.
BACKGROUND: Repolarization dynamicity (QT/RR) is supposed to be a prognostic marker in post-MI patients. However, data on the relationships between early and late phases of QT and RR intervals (QT peak/RR and T peak-T end/RR) are insufficient, and which ECG lead should be used for the analysis is unclear. We analyzed repolarization dynamicity in patients after anterior MI with and without VT/VF history using two leads of Holter recordings- modified V(5) and V(3) . The daytime and nighttime periods were also analyzed. METHODS: Cohort of 88 patients after anterior MI (>6 months) consisted of 43 patients without VT/VF (33 males; 59 ± 12 years; LVEF: 41 ± 7%; NoVT/VF), and 45 patients with VT/VF history- ICD implanted as secondary prevention (40 males; 64 ± 10 years; LVEF: 32 ± 8%; VT/VF). QT/RR, QT peak/RR and T peak-T end/RR were calculated from 24-hour ECG for the entire recording, daytime and nighttime periods, from V(5) and V(3) leads, respectively. RESULTS: VT/VF patients had lower LVEF (P = 0.001). There were no differences in age and gender. VT/VF group had steeper QT/RR, QT peak/RR, and T peak-T end/RR in V(5) : 0.233 ± 0.04 versus 0.150 ± 0.05, P = 0.0001, 0.181 ± 0.04 versus 0.120 ± 0.04, P = 0.0001, 0.052 ± 0.02 versus 0.030 ± 0.02, P = 0.0001, and in V(3) : 0.201 ± 0.04 versus 0.149 ± 0.05, P = 0.0001, 0.159 ± 0.03 versus 0.118 ± 0.04, P = 0.0001, and 0.042 ± 0.02 versus 0.031 ± 0.02, P = 0.004; respectively. VT/VF patients had higher indices in V(5) than in V(3) lead (P = 0.001). QT/RR and QT peak/RR were steeper at daytime period in both leads. It was not found for T peak-T end/RR. CONCLUSIONS: Patients with VT/VF history are characterized by steeper relationships between repolarization duration and RR intervals. These findings are more evident in modified V(5) lead.
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Szydło et al. (2012) conducted a cohort in Remote Anterior Myocardial Infarction (n=88). History of VT/VF vs. No history of VT/VF was evaluated on QT/RR slope in modified V5 lead (p=0.0001). Patients with a history of VT/VF after remote anterior myocardial infarction had significantly steeper QT/RR slopes in the modified V5 lead compared to those without (0.233 vs 0.150).
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