Patients with NSTEMI have prolonged QT as compared to patients with Unstable Angina

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1 Patients with NSTEMI have prolonged QT as compared to patients with Unstable Angina Rami Jubeh, Dan Tzivoni, Mady Moriel, Marc Klutstein, Sameer Mtour, Rivka Farkash, Aharon Medina. Dept of cardiology Shaare Zedek Medical Center, Jerusalem

2 No Conflict of Interest 2

3 Background Patients with Non ST Elevation Myocardial Infarction (NSTEMI) are at increased risk of cardiac death and subsequent infarctions, compared to patients with Unstable Angina Pectoris (UAP). An early diagnosis and treatment may improve outcome and reduce complications. 3

4 Objectives We aimed to investigate if QT interval prolongation may differentiate between NSTEMI and UAP. 4

5 Methods Patients hospitalized for NSTE ACS were included in the study if they had at least three digitized ECG tracings * : o o o upon admission after 24 hours pre discharge. QTc measurements : o QTc was calculated using the Bazett s formula o QT intervals were measured in V5 o Results were divided into deciles for further analyses. *(NORAV medical ltd.) 5

6 Methods continued Prolonged QTc was defined as 440 msec/ sec for males and 450 for females. Follow up ECGs were recorded in the outpatients clinic at least 90 days after the event. 6 acute coronary syndrome without MI

7 Study Population 2033 patients with NSTE ACS were admitted to the cardiology department between patients had at least 3 digitized ECGs and comprised our study population. Patients were dichotomized to NSTEMI or UAP by troponin I levels (0.08 μg/l). 7

8 Baseline Patients Characteristics ALL 802 UAP 234 (29%) NSTEMI 568 (71%) p value Female 210(26 %) 52 (25%) 158 (75%) 0.09 Age 65 years 449(55%) 106(24%) 343 (76%) < Hypertension 541 (67%) 172 (32%) 369 (68%) 0.02 Diabetes Mellitus 301 (37%) 91 (30%) 210 (70%) Hyperlipidemia 493 (61%) 172 (35%) 321 (65%) < Family History of IHD 171 (21%) 70 (41%) 101 (59%) < Smoker 309 (38%) 102 (33%) 207 (67%) Chi square test 8

9 ECG lead selection Mean QTc levels (msec/ sec) were 427 ± 43 in V5 and 427 ± 43 in V3. A high correlation was found between the two leads. Therefore V5 only was used for analyses. R s = 0.804, p <

10 Results QTc in NSTEMI vs. UAP All n=802 UAP n=234 NSTEMI n=568 p value 1 st ECG 424.6± ± ±42 < nd ECG 426.6± ± ±45 < rd ECG 420.8± ± ±41 <

11 QTc prolongation in NSTEMI vs. UAP 30% p< for all 25% 20% 189 (23.6%) 181 (25.6%) 150 (21.7%) 15% UAP 10% NSTEMI 5% 37 (4.6%) 42 (5.9%) 33 (4.8%) 0% 1 st ECG 226/802 (28%) nd ECG 223/706 (31%) 3 rd ECG 183/691 (26%) 11 acute coronary syndrome without MI

12 Multivariate Analysis: Independent Predictors for NSTEMI OR 95% CI p value Age over 65 years Hypertension <0.001 Hyperlipidemia < Family history QTc prolongation in 1 st ECG < Multivariate logistic model with NSTEMI as a dependent variable and QTc prolongation in 1 st ECG as explanatory variable, adjusted for age, gender, hypertension, hyperlipidemia, diabetes mellitus, family history of ischemic heart disease and smoking. 12

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15 Mechanism of QT prolongation 15??? Damage to subendocardial layer and exposure of M cells which cause prolongation of repolarization. Abnormal sensitivity to catecholamine. Parasympathetic effect Abnormal calcium influx during action potential

16 Conclusions QTc prolongation in the first ECG in the emergency ward, usually obtained before the results of Troponin levels, contributes to an early diagnosis of NSTEMI versus UAP. These results may have important implications regarding revascularization strategy in these patients. Further studies are needed to confirm our findings. 16