Risk factors and prognostic role of an electrical storm in patients after myocardial infarction with an implanted ICD for secondary prevention.

INTRODUCTION: The aim of our study was to determine the risk factors for electrical storm (ES) and to assess the impact of ES on the long-term prognosis in patients after myocardial infarction (MI) with an implantable cardioverter-defibrillator (ICD) for secondary prevention of sudden cardiac death (SCD). MATERIAL AND METHODS: We retrospectively analyzed 416 patients with coronary artery disease after MI who had an implanted ICD for secondary prevention of SCD. Fifty (12%) patients had one or more incidents of an electrical storm - the ES (+) group. We matched the reference group of 47 patients from 366 ES (-) patients. RESULTS: We analyzed 3,408 episodes of ventricular arrhythmias: 3,148 ventricular tachyarrhythmic episodes in the ES (+) group (including 187 episodes of ES) and 260 in the ES (-) group. Multivariate logistic regression showed that inferior wall MI (RR = 3.98, 95% CI: 1.52-10.41) and the absence of coronary revascularization (RR = 2.92, 95% CI: 1.18-7.21) were independent predictors of ES (p = 0.0014). During 6-year observation of 97 patients, there were 39 (40%) deaths: 25 (50%) subjects in the ES (+) group and 14 (30%) in the ES (-) group (p = 0.036). Independent predictors of death were: the occurrence of ES (HR = 1.93), older age (HR = 1.06), and lower left ventricular ejection fraction (HR = 0.95) (for all p < 0.001). CONCLUSIONS: Electrical storm in patients after MI with ICD for secondary prevention is a relatively common phenomenon and has a negative prognostic significance. Myocardial infarction of the inferior wall and the absence of coronary revascularization are predisposing factors for the occurrence of an ES.

Dynamicity of early and late phases of repolarization in patients with remote anterior myocardial infarction: the interlead differences.

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.

Impact of left ventricular remodeling on ventricular repolarization and heart rate variability in patients after myocardial infarction treated with primary PCI: prospective 6 months follow-up.

BACKGROUND: The relation between postinfarction left ventricle remodeling (LVR), autonomic nervous system and repolarization process is unclear. Purpose of the study was to assess the influence of LVR on the early (QTpeak) and late (TpeakTend) repolarization periods in patients after myocardial infarction (MI) treated with primary PCI. The day-to-night differences of repolarization parameters and the relation between QT and heart rate variability (HRV) indices, as well left ventricle function were also assessed. METHODS: The study cohort of 104 pts was examined 6 months after acute MI. HRV and QT indices (corrected to the heart rate) were obtained from the entire 24-hour Holter recording, daytime and nighttime periods. RESULTS: LVR was found in 33 patients (31.7%). The study groups (LVR+ vs LVR-) did not differ in age, the extent of coronary artery lesions and treatment. Left ventricle ejection fraction (LVEF) was lower (38%+/- 11% vs 55%+/- 11%, P < 0.001), both QTc (443 +/- 26 ms vs 420 +/- 20 ms, P < 0.001) and TpeakTendc (98 +/- 11 ms vs 84 +/- 12 ms, P < 0.005) were longer in LVR + patients, with no differences for QTpeakc. Trends toward lower values of time-domain (SDRR, rMSSD) HRV parameters were found in LVR+ pts. Day-to-night difference was observed only for SDRR, more marked in LVR-group. Remarkable relations between delta LVEF (6 months minus baseline), delta LVEDV and TpeakTendc were found, with no such relationships for QTpeakc. CONCLUSIONS: The patients with LVR have longer repolarization time, especially the late phase-TpeakTend, which represents transmural dispersion of repolarization. Its prolongation seems to be related to local attributes of myocardium and global function of the left ventricle but unrelated to the autonomic nervous influences. Remodeling with moderate LV systolic dysfunction is associated with insignificant decrease in HRV indices and preserved circadian variability.

QT/RR relationship in patients after remote anterior myocardial infarction with left ventricular dysfunction and different types of ventricular arrhythmias.

BACKGROUND: QT/RR relationship was found to be both rate-dependent and rate-independent, what suggests the influence of autonomic drive and other not-autonomic related factors on it. The steeper QT/RR slope in patients after acute myocardial infarction (MI) was described, but the relationship to ventricular arrhythmias is unknown. The purpose of this study was to calculate differences in QT/RR relationship in patients after remote anterior MI with left ventricular dysfunction and different types of ventricular arrhythmias. METHODS: The cohort of 95 patients (age: 63 +/- 11 years, LVEF: 35 +/- 9%) with previous anterior MI (mean 1.1 years) was divided into two well-matched groups-50 patients without episodes of ventricular tachycardia (VT) or ventricular fibrillation (VF) (NoVT/VF: 39 males, 64 +/- 12 years, LVEF 37 +/- 8%) and 45 patients with VT and/or VF (all with ICD implanted) (VT/VF: 35 males, 62 +/- 10 years, LVEF 34 +/- 10%). No true antiarrhythmics were used. QT/RR slope was calculated from 24-hour Holter ECG for the entire recording (E), daytime (D) and nighttime (N) periods. RESULTS: Groups did not differ in basic clinical data (age, LVEF, treatment). QT/RR slopes were steeper in VT/VF than in NoVT/VF group in all analyzed periods: E - 0.195 +/- 0.03 versus 0.15 +/- 0.03 (P < 0.001), N - 0.190 +/- 0.03 versus 0.138 +/- 0.03 (P < 0.001) and D - 0.200 +/- 0.04 versus 0.152 +/- 0.03 (P < 0.001). No significant day-to-night differences were found in both groups. CONCLUSIONS: Steeper QT/RR slope and complete lack of day-to-night differences in VT/VF patients show inappropriate QT adaptation to the heart rate changes. The prognostic significance of this parameter needs prospective studies.

[Prediction of adverse cardiac events in patients with acute anterior wall myocardial infarction treated with PCI]. / Przewidywanie wystapienia niekorzystnych zdarzen sercowych u chorych ze swiezym zawalem miesnia sercowego sciany przedniej leczonych PCI.

UNLABELLED: Despite common use of reperfusion therapy, particularly primary PCI during acute myocardial infarction, steadily increasing number of patients with low left ventricular ejection fraction, with heart failure (HF), requiring frequent rehospitalisation justifies the study establishing the best indices of prediction of major adverse cardiac events (MACE) occurrence. The aim of the study was to define the frequency of MACE (death, re MI, sVT, rehospitalisation for HF) in patients with acute anterior wall myocardial infarction in 6 month follow up and the factors determinatig its occurence. The 115 consecutive patients (86 males of age 57.7 +/- 11 yrs) with first anterior MI were studied. After successful PCI (TIMI 3) the angiographic assessment was performed (MBG 0-1 - no perfusion, MBG 2-3 - perfusion preserved). During first 48 hours 12-lead ECG was monitored in order to analyse the time to reduction of ST elevation in the lead with the highest elevation (deltatST 50%). On 2nd day LV function (LVEF and WMSI) and dyssfunctional segment perfusion (RPSI) were assessed. On 5th day Holter monitoring with arrhythmia and time domain parameters (SDNN, rMSSD) of heart rate variability were performed, on 30 day TWA test was done. RESULTS: During 180 follow-up 18 MACE occurred (3 death, 2 MI, 11 rehospitalisations for HF). In univariate analysis cigarette smoking, higher maximum troponin I value, LVEDV, LVESV, ST elevation sum, longer time to reduction of ST elevation, lower LVEF and RPSI, lack of microvessel integrity and positive TWA test had significant relationship with occurrence of MACE. The multivariate analysis of Cox proportional risk regression demonstrated that only lower value of RPSI and LVEF, longer time of ST elevation reduction in the lead with the highest ST elevation and positive TWA test were independent indices of MACE prediction. CONCLUSIONS: Cumulative evaluation of LVEF, indices of preserved perfusion and results of TWA test turned out to be the best predictors of MACE occurrence in 6 month follow up in patients after anterior MI treated with PCI.

Relationship between duration of repolarisation and T wave amplitude in patients with positive or negative T wave alternans.

BACKGROUND: Experimental studies documented the relationship between T wave alternans (TWA) and duration of refractoriness. To date, association between TWA and QT interval on standard ECG has not been examined. Aim. To assess the relationship between TWA and QT interval. METHODS: The study group consisted of 70 patients (57 males, mean age 56+/-16 years) with implantable cardioverterdefibrillator (ICD). TWA was measured using a high-resolution ECG obtained from surface orthogonal bipolar XYZ leads and analysed using a Fast Fourier transform. All recordings were performed during ventricular pacing at 100 betas/min. Correlation between T wave amplitude (T max) and QT interval (measured from R wave to T max) was calculated. RESULTS: TWA was found in 18 patients. In this group of patients, there was a significant positive correlation between Tmax and QT (r = 0.766), whereas in patients with negative TWA no such correlation was detected. CONCLUSIONS: (1) Positive correlation between QT and T max probably depicts the relationship between T wave amplitude and duration of repolarisation, which is associated with TWA; (2) methods used for T wave localisation, based on the identification of Q wave (with possible QT-RR correction) overestimate TWA due to periodic changes (with TWA frequency) in location of T wave in the analysed window; and (3) these results provide new insights in the genesis of TWA.