Syncope and collapse in acute pulmonary embolism.

BACKGROUND

Syncope and collapse (=presyncope) are 2 symptoms of pulmonary embolism (PE), which are suspected of being connected with poorer outcome, regardless of haemodynamic instability. However, pathomechanisms are not completely understood. We aimed to investigate these pathomechanisms in regard to blood pressure and heart rate of syncope/collapse in PE.

METHODS

We performed a retrospective study of consecutive PE patients, who were treated in the Internal Medicine Department. Patients with and without syncope/collapse were compared. Regression models for associations between syncope/collapse and blood pressure, heart rate and shock index (SI) were computed. Moreover we calculated ROC analyses and Youden indices for effectiveness and cut-off-values of these parameters for the probability of syncope/collapse.

RESULTS

182 patients (mean-age 68.5±15.3years; 61.5% female) with confirmed PE were included in this study. 20 PE patients (11.0%) showed a syncope/collapse. PE patients with syncope/collapse were in median 7.5years older (78.5 (72.0/82.3) vs. 71.0 (61.0/80.0) years, P=.0575), had lower systolic (132.0 (108.8/154.0) vs. 145.5 (127.0/166.0) mmHg, P=.0845) and diastolic (70.0±27.0 vs. 78.4±18.4mmHg, P=.0740) blood pressure, whereas heart rate (103.5 (87.8/116.0) vs. 90.0 (76.0/102.0)beats/min, P=.0518), SI (0.78 (0.65/1.01) vs. 0.60(0.50/0.79), P=.0127) and frequency of right ventricular dysfunction (RVD) (88.2% vs. 55.8%, P=.0294) were higher in PE patients with syncope/collapse than in those without. Hypotension (systolic blood pressure<90mmHg), tachycardia and SI>1.0were connected with 6.4-fold, 2.5-fold and 5.8-fold higher probability of syncope/collapse, respectively. ROC analyses revealed cut-off values of ≤110mmHg, ≥107beats/min and >0.62 for systolic blood pressure, heart rate and SI with low AUC values, respectively.

CONCLUSIONS

The pathomechanism of syncope/collapse in patients with acute PE seems to be connected with blood pressure fall, heart rate increase and RVD, in terms of cardiovascular syncope with reduced cardiac output and vasovagal reflex.