Epidemiology of cardiac arrhythmias in a medical-cardiologic intensive care unit: single center experience

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Aim of study

To obtain frequency and distribution of various types of significant, sustained arrhythmia (ARRHY), its time of occurrence and factors influencing the occurrence of ARRHY in a prospective observational study in a medical-cardiologic ICU.

Results

There were 310 ARRHY episodes in 133 patients (94 m, 39 f; age 65± 12 years) during 11/1996 and 7/1999 (2.91 ARRHY episodes/patient, range 1-14). 278 episodes were tachyarrhythmias (TACHY; narrow-QRS complex [N-QRS] n=108, wide-QRS complex [W-QRS] TACHY n=169; regular n=179, irregular n=98) and 32 bradycardias. One case of primary ventricular fibrillation was classified as TACHY but not with respect to QRS width and regularity. The number of patients showing significant ARRHY was relatively constant over the years (1996: 4/28 [14.3%], 1997: 50/302 [16.5%], 1998: 51/286 [17.8%], 22/140 (15.7%) until 7/1999). 135/278 (48.6%) W-QRS TACHY were assigned ventricular TACHY (VT).12 W-QRS TACHY episodes could not be classified with certainty. There were 13 episodes of Torsade de pointes (4.8%). N-QRS TACHY episodes were atrial fibrillation (AFIB) 83, atrial flutter 10, supraventricular TACHY 21, ectopic junctional TACHY 1. The occurrence of ARRHY followed a circadian pattern showing a peak during daytime and a decline in the evening hours and early morning (Fig. 1). TACHY were treated electrically (n=19), pharmacologically (n=139) or combined (n=77). The antiarrhythmic drugs most frequently used were amiodarone (n=129), diltiazem (n=47), ibutilide (n=21), lidocaine (n=24) and digitalis (n=18). Proarrhythmia occurred due to haloperidol (n=4), cisapride (n=2), ibutilide (n=1), and amiodarone (n=4). Sedoanalgesia (P=0.64), mechanical ventilation (P=0.76) or catecholamine treatment (P=0.63) had no influence on the diurnal distribution of ARRHY. During 270/310 (90%) episodes there was an elevated C-reactive protein (CRP), in 176/310 (56.8%) an elevated leukocyte count [L] and in 230/310 (74%) episodes were there elevated fibrinogen levels (FGEN). These inflammation parameters on the day of ARRHY did not differ significantly when compared to the respective values 24 and 48 h before ARRHY onset (CRP 16.6± 11, 16.3± 11, 16± 1 mg/dl, P=0.9; L 11.4± 5, 11.5± 5, 11.9± 5.7 G/l, P=0.7; FGEN 545± 221, 565± 208, 582± 221 mg/dl, P=0.26).

Conclusions

1) Clinically significant, sustained ARRHY occurred in ~ 1/5 of patients in this medical-cardiologic ICU. 2) VT and AFIB were the single most frequent ARRHY. 3) ARRHY followed a circadian pattern irrespective of the presence of sedoanalgesia, mechanical ventilation or catecholamine support. 4) The vast majority of ARRHY occurred while there were signs of inflammation without preponderance to the ascending or descending limb of inflammation.

Figure 1