Krzysztof Szydło

Dispersion of the QT interval as a predictor of cardiac death in patients with coronary heart disease.

Abnormal dispersion of the QT interval (QTd), measured as interlead variability of QT, may reflect a regional variation in duration of ventricular action potential and, hence, of cardiac electrical instability. In this retrospective study, we analyzed the effect of QTd on survival and its relation to other known predictors of subsequent cardiac death (CD) and sudden cardiac death (SCD) in 162 patients with coronary heart disease (CHD). QTd was calculated as the difference between the highest and lowest values measured in each of the 12 ECG leads (Qtmax ‐ QTmin). Seventeen CDs occurred, including nine SCDs, during a 25 ± 11 month follow‐up. There were significant differences in CD (P < 0.001 in log‐rank test) and in SCD (P < 0.01). The 1‐ and 3‐year survivals were 87.5% and 76.5% in patients with QTd > 0.060 seconds versus 98% and 93.5% in patients with QTd < 0.060 seconds, respectively. Additionally, a stepwise Cox regression analysis revealed that increased QTd was an independent risk factor of CD and SCD. A cut‐off value of 60 ms for QTd had a 53% sensitivity and 79% specificity in discriminating patients who are at risk of CD. The positive and negative prognostic values were 23% and 93%, respectively. Our findings support the hypothesis that increased QTd has a prognostic value in the stratification of patients with CHD independent of other known risk factors.

Correlation of Heart Rate Variability Parameters and QT Interval in Patients After PTCA of Infarct Related Coronary Artery as an Indicator of Improved Autonomic Regulation

The purpose of this study was to determine if PTCA of the infarct related coronary artery (IRA) in the late phase of myocardial infarction (MI) can improve autonomic regulation of sinus rhythm and electrical stability of the myocardium measured by heart rate variability (HRV), QT, QTc, and its dispersion (QTd) and if any correlation exists among these measures. The study was performed in 25 patients (21 male, age: 50 ± 9 years, EF: 52%± 11%) in the late phase of MI (2.5 ± 1.5 months). HRV parameters were calculated automatically. QT, QTc, and QTd were measured manually from a 12‐lead surface ECG (50 mm/s). All measurements were made before and 3–5 days after PTCA. Day and night parameters of HRV were sampled over two periods: 2 pm to 10 pm (day) and 10 pm to 6 am (night). Parameters of HRV measured from whole recordings were significantly higher after successful PTCA: SDRR (116 31 vs 128 ± 38 ms), SD (55 ± 17 vs 62 ± 22 ms), rMSSD (30 ± 13 vs 36 ± 14 ms) and HF (246 ± 103 vs 417 ± 224 ms2). Significant differences were found during daytime for SD, rMSSD, and HF, and during nighttime for SDRR, SDANN. QT interval duration, QT corrected to the heart rate, and QT dispersion were significantly lower after PTCA (QTd: 54 ± 15 vs 39 ± 12 ms). There was no correlation between HRV and QT values before PTCA. High correlations were found after the procedure, particularly between QTd and nighttime HRV. Conclusions: PTCA of IRA in the late phase of MI enhances sympathovagal regulation of the cardiac rhythm and the electrical stability of the heart, which may be prognostically important.

Value of Heart Rate Variability Parameters for Prediction of Serious Arrhythmic Events in Patients with Malignant Ventricular Arrhythmias

Heart rate variability (HRV) assesses the electrical stability of the heart and can identify patients at risk of sudden cardiac death (SCD). The value of 10 HRV parameters from 24 hour ECG (in both time and frequency domain) to predict serious arrhythmic events (SAE) in a group of 56 patients with ventricular tachycardia and/or ventricular fibrillation of different etiologies not due to acute myocardial infarction was explored. Eighteen patients had low left ventricular ejection fractions (LVEF). During follow‐up (6–46 months, mean = 24) 8 SCD and 12 recurrences of malignant ventricular arrhythmias or ICD discharges were recorded. Proportional hazard analysis (Cox model) for SAE revealed that the mean of all 5 minute standard deviation of RR intervals (SD) and the amplitude of low frequency spectrum (L) were independent risk factors of SAE (P < 0.05). The best models were: SD+EF and L+EF where predictive values were high (sensitivity approximately 60%, specificity over 95%, positive predictive value over 90% and negative predictive value approximately 80%). Event‐free survival curves revealed a significantly shorter survival in patients with EF < 40%: 47% vs. 92%, SD < 43 ms; 56% vs. 92% and L < 16 ms; 56% vs. 89% (all P < 0.001) after 2 years. The subgroup with low EF and SD < 43 ms revealed a significantly shortened survival (27% vs 83% at 2 years, P < 0.01). Some HRV parameters, SD from the time and L from the frequency domain, were predictive of a fatal outcome in VT/VF patients. Combined SD +EF and L +EF values are powerful predictors of serious arrhythmic events.

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.

Heart Rate Variability: Its Association with Hemodynamic Function of the Left Ventricle in Patients with Coronary Heart Disease

Patients with heart failure secondary to coronary heart disease (CHD) are characterized by an imbalance of the autonomic nervous system, which can be assessed by analysis of the heart rate variability (HRV). However it is still unclear whether all patients with CHD reveal suppression of HRV and if it is related to hemodynamic function and contractile disturbances of the left ventricle. To answer these questions data from 105 consecutive patients were analyzed and compared with 17 healthy subjects. All study participants underwent 24‐hour ambulatory ECG recordings with calculation of HRV parameters and angiographic examination after collection of clinical data and other noninvasive evaluations. Time‐ (SDRR, SDANN, SD, pNN50) and frequency‐ (LF, HF) domain parameters of HRV were assessed. All ventriculographic and hemodynamic measurements were used in the analysis. Highly significant correlations were found between all HRV parameters, and left ventricular ejection fraction (LVEF) and left ventricular end‐diastolic pressure (P < 0.001). Patients with LVEF < 40% were characterized by significantly lower values of HRV and impairment or lack (LVEF < 20%) of diurnal variation of frequency‐domain measurements of HRV. Patients with segmental akinesis or dyskinesis also had lower values of HRV. The group with dyskinesis was characterized by significantly lower diurnal rhythms of LF and HF, independent of LVEF.

Microvascular damage prevention with thrombaspiration during primary percutaneous intervention in acute myocardial infarction.

BackgroundDespite rapid and complete recanalization of infarct-related artery with percutaneous coronary intervention, microvascular integrity is not often preserved. Several mechanical devices have been proposed to prevent distal embolization, but the impact of these devices on myocardial perfusion remains controversial. AimThe aim of our study was to assess microvascular damage reduction with quantitative myocardial contrast perfusion echocardiography among patients with the first anterior acute myocardial infarction treated with thromboaspiration during percutaneous coronary intervention. MethodsForty-two patients (57.4±10 years, 74% males) with first anterior acute myocardial infarction were randomized 1 : 1 to intracoronary thromboaspiration followed by stenting, or to a conventional strategy of stenting alone. Echocardiogram and quantitative myocardial contrast echocardiography were performed 7 days and 1 month later, respectively. Parameter A (reflecting myocardial blood volume), &bgr; (reflecting velocity, myocardial blood flow), and product of A and &bgr; as indicator of myocardial blood flow were analyzed. For each patient mean value of A, &bgr;, and A×&bgr; from all dysfunctional segments was calculated. ResultsThe study population was divided into two groups: thromboaspiration (group I, 19 patients) and stenting alone (group II, 23 patients). No difference was observed between the both groups in demographic, clinical, echocardiographic, and angiographic data. Parameter A and A×&bgr; were significantly higher in group I than in group II: 8.58±2.54 versus 5.29±3.18 dB (P<0.001) and 5.29±3.73 versus 2.78±3.03 dB/s (P<0.001). Multivariate step-down regression analysis revealed that only thromboaspiration before stenting and lower maximum troponin I have been associated with viability preservation in infarcted region. ConclusionThromboaspiration before stenting in patients with the first anterior myocardial infarction improves myocardial perfusion at the tissue level assessed by quantitative myocardial contrast echocardiography.

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.

Postextrasystolic repolarization abnormalities in ST-U segment in patients with ventricular arrhythmias.

Background: Changes in U‐wave amplitude after premature ventricular contractions (PVC) are known as prognostic markers in the long QT syndrome dependent on bradycardia. The purpose of the study was to find correlation between postextrasystolic ST‐U segment changes and a history of sustained ventricular tachycardia or ventricular fibrillation (VT/VF).

Role of left atrial speckle tracking echocardiography in predicting persistent atrial fibrillation electrical cardioversion success and sinus rhythm maintenance at 6 months.

PURPOSE We assessed the value of left atrium speckle tracking imaging (STI) indices, and clinical and other echocardiographic parameters in persistent atrial fibrillation (AF) patients to predict the efficacy of electrical cardioversion (EC) and sinus rhythm (SR) maintenance at 6 months. MATERIAL/METHODS Eighty persistent AF patients planned to receive EC, underwent echocardiography including STI. After 24h, patients with successful EC were examined to predict SR maintenance. After 6 months patients with no AF recurrence in electrocardiogram (ECG) underwent 7-day ECG to exclude silent AF. Every AF>1 min was a recurrence. RESULTS SR restored in 61 patients, 19 unsuccessful. Prior use of statins (68.8% vs. 42.1%, p=0.03) was the only factor, determined later by univariate analysis to be a significant EC success predictor (OR=1.09, CL ± 95% 1.001-1.019, p<0.03). Both groups received similar antiarrhythmics and had similar echocardiographic parameters. After 6 months, SR was maintained in 19 patients (31.1%, Group I); AF recurrences were registered in 42 patients (68.8%, Group II). In Group I, only the mitral valve deceleration time (MVDT) 224.18 ± 88.13 vs. 181.6 ± 60.6 in Group II, p=0.04) and the dispersion of time to peak longitudinal strain (dTPLS) (86.0 ± 68.3 vs. 151.8 ± 89.6, p=0.03) differed significantly. The univariate analysis revealed dTPLS as a significant predictor of SR maintenance. CONCLUSION High EC efficacy and frequent AF recurrences were observed. The dispersion of time to the maximal longitudinal strain (LS) of left atrial segments facilitated prediction of SR maintenance. The value of 7-day ECG monitoring for detection of arrhythmia after 6 months was limited.

Differentiation of arrhythmia originating from the right or left ventricular outflow tract based on the QRS morphology of premature ventricular beats and duration of repolarisation

BACKGROUND Premature ventricular beats (PVBs) and monomorphic ventricular tachycardia originating from the right ventricular outflow tract (RVOT) are the most frequent forms of idiopathic ventricular arrhythmias, but arrhythmia originating from the left ventricular outflow tract (LVOT) may be found in about 10% of these patients. AIM To compare electrocardiographic (ECG) patterns and duration of repolarisation after PVBs originating from the left and right superior part of the interventricular septum which were successfully treated with radiofrequency catheter ablation. METHODS We studied 62 patients who did not receive antiarrhythmic drug treatment before ablation, including 50 patients with RVOT arrhythmia (21 males, mean age 42 ± 14 years, left ventricular ejection fraction [LVEF] 61 ± 6%) and 12 patients with LVOT arrhythmia (3 males, mean age 41 ± 17 years, LVEF 59 ± 9%). Pre-ablation 24-h Holter ECG recordings were analysed for the total number of PVBs. In addition, we evaluated ectopic beat QRS duration, prematurity index and duration of repolarisation (QT interval, JT interval and TpeakTend values uncorrected for the heart rate) based on ten random daytime PVBs during a period of stable sinus rhythm at a rate of 60-70 bpm. RESULTS The study groups did not differ by age, LVEF, heart rate and the number of PVBs. RVOT arrhythmia was characterised by a lower prematurity index (0.59 ± 0.11 vs. 0.72 ± 0.09, p = 0.001) and a lower R/S ratio in leads V1-V3 (p < 0.01 for each lead). QRS duration of right-sided PVBs was shorter compared to that of left-sided PVBs (147 ± 13 vs. 166 ± 13 ms, p = 0.002), QT and JT intervals were similar (QT: 422 ± 32 vs. 429 ± 27 ms, p = 0.35; JT: 272 ± 27 vs. 266 ± 27 ms, p = 0.31), and TpeakTend was shorter in RVOT arrhythmia (100 ± 10 vs. 110 ± 6 ms, p = 0.01). Combination of R > S in lead V3 and TpeakTend-PVB > 110 ms identified LVOT arrhythmia with a sensitivity of 75% and specificity of 96%. CONCLUSIONS Ventricular arrhythmias originating from the left or right superior part of the interventricular septum are not only characterised by different ECG patterns of ventricular ectopic beats but also show significant differences in the repolarisation phase.