QRS broadening due to terminal distortion is associated with the size of myocardial injury in experimental myocardial infarction

Clinical outcomes of ST-elevation myocardial infarction patients who present special forms of ST-segment elevation

BACKGROUND

There are several patterns of special ST-segment elevation morphology in patients with ST-elevation myocardial infarction (STEMI), but their effect on prognosis is unclear. We, therefore, investigated the mortality of patients with these patterns by comparing them to patients with typical ST-segment morphologies.

METHODS

This observational study assessed 1277 consecutive patients with STEMI. Their initial electrocardiograms were analyzed quantitatively and divided into four categories: typical (n = 1138), Tombstone (n = 62), Triangular (n = 39), and Lambda patterns (n = 38). The primary outcome was death (all causes).

RESULTS

The Triangular and Lambda pattern patients had high proportions of cardiogenic shock (15.8%, 9.7%, 66.7%, and 47.4%, P < 0.01, for typical, Tombstone, Triangular, and Lambda, respectively) and out-of-hospital cardio-pulmonary arrests (4.8%, 6.5%, 38.5%, and 26.3%, P < 0.01). They also had higher frequencies of multivessel disease (37.2%, 30.7%, 66.7%, and 55.3%, P < 0.01) and left main trunk lesion (2.8%, 0%, 35.9%, and 13.2%, P < 0.01). During a median observation period of 717 days, the mortality rates were 18.3%, 17.7%, 71.8%, and 52.6% (P < 0.01; 7.4%, 9.7%, 53.9%, and 42.1% within 30-days, P < 0.01), respectively. The hazard ratios were 1.3 (95% CI: 0.6-3.0. P = 0.51) in Tombstone, 9.6 (95% CI: 6.0-15.3, P < 0.01) in Triangular, and 6.7 (95% CI: 4.0-11.2, P < 0.01) in Lambda patterns when referenced to typical patterns.

CONCLUSION

The mortality rate in STEMI patients with Triangular and Lambda patterns was higher than that of those with typical and Tombstone patterns.

Ischemic QRS prolongation as a predictor of ventricular fibrillation in a canine model

OBJECTIVES

An acute coronary occlusion and its possible subsequent complications is one of the most common causes of death. One such complication is ventricular fibrillation (VF) due to myocardial ischemia. The severity of ischemia is related to the amount of coronary arterial collateral flow. In dog studies collateral flow has also been shown to be associated with QRS prolongation. The aim of this study was to investigate whether ischemic QRS prolongation (IQP) is associated with impending VF in an experimental acute ischemia dog model.

METHODS

Degree of IQP and occurrence of VF were measured in dogs (n = 21) during coronary occlusion for 15 min and also during subsequent reperfusion (experiments conducted in 1984).

RESULTS

There was a significant difference in absolute IQP between dogs which developed VF during reperfusion (47 ± 29 ms, mean ± SD) and those which did not (12 ± 10 ms; p = .001).

CONCLUSIONS

IQP during acute coronary occlusion is associated with reperfusion VF in an experimental dog model and might therefore be a potential predictor of malignant arrhythmias in patients with acute coronary syndrome.