Prolonged QT interval in ST-elevation myocardial infarction and mortality: new prognostic scale with QT, Killip and
Ricardo Rivera-Fernández1, Maria Dolores Arias-Verdú, Teresa García-Paredes
1aIntensive Care Unit bCoronary Care Unit, Hospital Carlos Haya, Malaga cCIBERESP, Preventive Medicine and Public Health, University of Jaen dIntensive Care Unit, Hospital Infanta Margarita, Cabra (Cordoba), Spain.
Insights
Prolonged corrected QT interval (QTc) is linked to higher mortality in ST-elevation myocardial infarction patients. This finding complements existing risk scores like TIMI and APACHE-II, improving patient outcome prediction.
Area of Science:
- Cardiology
- Clinical Research
- Electrocardiography
Background:
- ST-elevation myocardial infarction (STEMI) is a critical condition with significant mortality.
- Risk stratification in STEMI patients is crucial for timely and effective treatment.
- Existing prognostic scales like Killip, Thrombolysis in Myocardial Infarction (TIMI), and Acute Physiology and Chronic Health Evaluation-II (APACHE-II) aid in risk assessment.
Purpose of the Study:
- To investigate the association between a prolonged corrected QT interval (QTc) and mortality in STEMI patients.
- To evaluate the complementary role of QTc interval in enhancing the predictive power of established risk scales (Killip, TIMI, APACHE-II).
Main Methods:
- A nested case-control study was conducted on 524 STEMI patients admitted between 2008 and 2010.
- Cases included 38 deceased patients, and controls were 81 randomly selected survivors.
- The corrected QT (QTc) interval was measured from the first electrocardiogram (ECG) obtained pre-hospital or upon admission.
Main Results:
- A prolonged QTc interval was observed in 51.4% of deceased patients versus 16.7% of survivors (P < 0.001).
- Higher APACHE-II, TIMI, and Killip scores were significantly associated with mortality (P < 0.001).
- A new prognostic score incorporating QTc, age, and Killip class demonstrated good discrimination (ROC area: 0.88).
Conclusions:
- Prolonged QTc at admission is an independent predictor of higher hospital mortality in STEMI patients.
- Incorporating QTc interval measurement significantly improves the discriminatory ability of existing risk stratification models.
- A novel, simple prognostic scale combining QTc, age, and Killip class offers robust predictive value for STEMI outcomes.
Aims:
To analyze the relation between prolonged QT interval and mortality in patients with ST-elevation myocardial infarction and complementarity with Killip, Thrombolysis in Myocardial Infarction (TIMI) and Acute Physiology and Chronic Health Evaluation-II (APACHE-II) scales.
Methods:
A nested cohort case-control study was conducted in a Spanish hospital. The cohort consisted of patients with ST-elevation myocardial infarction admitted between 2008 and 2010 (n = 524). The cases were the patients who died (n = 38) and the controls (n = 81) were a random sample of those who survived (one of every six).
Results:
The corrected QT (QTc) interval of first ECG (prehospital-or-hospital admission) was prolonged in 18 of the 35 patients who died (51.4%) and in 12 of the controls (16.7%; P < 0.001). APACHE-II, TIMI and Killip scores were higher in the patients who had died (P < 0.001). Mortality with prolonged QTc (19.3%) was 20%, and 4.5% were with normal QTc (80.7%; P < 0.001).Logistic regression showed a relation between mortality with prolonged QTc and TIMI [odds ratio (OR) 3.57(1.16-10.97)]. A second model was constructed with APACHE-II and prolonged QTc [OR 6.47(1.77-23.59)]; receiver operating characteristic (ROC) curve area [0.92(0.87-0.97)], and individually, for APACHE-II was 0.88 (0.81-0.95). A new score was constructed: QTc (not prolonged: 0 points, prolonged: 7 points), age (<65 years: 0 points, 65-74 years: 6 points, ≥75 years: 9 points), Killip (I: 0 points, II-III: 4 points, IV: 17 points). ROC area: 0.88.
Conclusions:
Hospital mortality was higher with prolonged QTc at prehospital-or-hospital admission, given equal Killip, TIMI and APACHE values. Discrimination of Killip, TIMI and APACHE values can be improved with prolonged QTc. Discrimination of a model including Killip, age and prolonged QTc is quite good. We have made a new simple prognostic scale with these variables.
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