|Author, date and country||Patient group||Study type (level of evidence)||Outcomes||Key results||Study Weaknesses|
|McCabe et al.|
|Total no. of adult patients 37. Total no. of adult patients with SVT 26. 7 were unstable. Setting: an urban Emergency Medical Services system (paramedics).||Prospective, consecutive case series.||Conversion rate to sinus rhythm in unstable patients with PSVT.||Overall success rate 88% and 100% in unstable patients with PSVT.||Small number of patients but otherwise well designed.|
|Safety of Adenosine in unstable patients.||Recurrence rate 3%.|
|Adverse effects occurred in16% of all patients and were transient (chest pain, flushing and dyspnoea). There was no differential rate of complications given for stable and unstable patients but there was no haemodynamic deterioration in any patient|
|Melio et al.|
|12 adult patients with unstable PSVT over 2 yrs. Setting: university-affiliated hospital Emergency Department.||Retrospective chart review.||Conversion rate to sinus rhythm in unstable patients with PSVT.||Success rate 100%.||Retrospective Chart Review. Small number of patients.|
|Safety of Adenosine in unstable patients.||Recurrence rate 0%.|
|No complications encountered.|
|Side effects were transient and were not clinically significant.|
|Marco et al|
|Total no. of adult patients 72. no. of patients with PSVT 46. 38 patients had unstable PSVT. Setting: an urban, university-affiliated Emergency Department.||Retrospective chart review.||Conversion rate to sinus rhythm.||Overall success rate 84.8%.||Retrospective chart review but otherwise well designed.|
|Rate and significance of adverse effects of Adenosine.||Overall recurrence rate 4.1%.|
|Side effects were transient and none were clinically significant(flushing, light-headedness, unsustained VT, chest discomfort, nausea).|
|Gausche et al|
|Total no. of adult patients 129. Total no. of adult patients with PSVT 85. 60 were unstable. Setting: large, urban, advanced life support Emergency Medical Services system (paramedics).||Prospective case series.||Conversion rate in unstable patients with PSVT.||Overall success rate 85%. (94% in patients with previous history of PSVT compared with 77% of those without such a history).||Well designed prospective study.|
This study was the first large series of unstable patients in PSVT who were successfully treated with Adenosine.
Conversion rate of unstable patients with PSVT was not mentioned.
Patients who presented with unstable PSVT had no increase in complication rate after administration of adenosine as compared to stable patients. Larger proportion than expected was stated to be unstable. The criteria for this were chest pain, systolic BP below 90 mmHg or pulmonary oedema.
|incidence of adverse events.||Overall incidence of adverse effects 10%. all transient and none serious|
|Lozano et al.|
|Total no. of adult patients 239 in study group. 228 in control group. Total no. of patients with PSVT 133 in study group, 88 in control group. Setting: large urban municipal Emergency Medical Services system (paramedics).||Prospective observational case series with historical controls.||Conversion rate to sinus rhythm in stable and unstable patients with PSVT. Criteria for treatment with adenosine were chest pain, evidence of myocardial ischaemia or shock||Success rate in unstable group of patients was 67.3%.||Historical controls. Not focused on side effects. Large number of patients lost to analysis mainly due to unavailability of records.|
|SVT recurrence rate.||Overall recurrence rate 9% after using Adenosine.|
|Losek et al.|
|82 paediatric patients with total of 98 PSVT events. 52 prospective 46 retrospective pts events. Setting: 7 urban paediatric Emergency Departments.||Multicentre study with both prospective and retrospective patient entry.||Safety of Adenosine with unstable SVT.||Success rate 74.7%.||Paediatric pts with all types of medical and cardiac problems were included, including post cardiac surgery.|
The original design was prospective, but retrospective patients were added to increase the study population.
The 2 centres that entered patients only prospectively may have missed eligible pts. Therefore, the results of this study might not be generalisable to the target population. Clinical factors not recorded in the medical records of patients entered into the study retrospectively were considered to be negative. Therefore, the true number of adverse effects may have been greater than reported although the rate of adverse events was similar for patients entered retrospectively compared with those entered prospectively.
|Incidence of adverse effects especially bronchospasm.||Success rate among 10 patients with multiple events 88%.|
|Success rate in patients with PSVT and compensated heart failure 80%.|
|Side effects occurred in 22% but none were severe (vomiting, chest pain, headache, flushing, transient arrhythmia). No sustained arrhythmia or bronchospam was observed. A greater incidence of side-effects occurred in patients aged 1 year or older or who had had cardiac surgery or who had no signs of cardiac shock.|
|No bronchospasm reported in 13 asthmatic pts.|
|Adenosine treatment of VT misinterpreted as SVT did not appear to be associated with serious adverse effects.|
|Clarke et al.|
|3 newborn infants and one older child. The 3 newborns were described as being severely ill and in cardiac failure due to long-term spontaneously occurring SVT. No data was given about the stability of the older child. Setting: hospital.||Prospective case series.||Conversion rate in unstable patients.||Success rate 100%.||Very small number of patients.|
|Incidence of adverse events.||No untoward effects were observed.|
|Elkayam et al.|
|38 arrhythmic episodes (37 PSVT, 1 atrial flutter) in 33 pregnant women.
Data were collected by four methods:|
1. by Questionnaire.
3. Medline review.
4. Data were obtained in 2 patients directly from LA county hospital.
|Retrospective survey.||Conversion rate in pregnant women with SVT.||Success rate 89%.||Retrospective survey. |
Provides data indicating overall safety and efficacy of intravenous Adenosine for the rapid termination of PSVT during the second and third trimester of pregnancy. (Further study is necessary to determine the safety of Adenosine use during the first trimester of pregnancy).
Did not mention the number of unstable pregnant women although some of the cases included in this survey were described as unstable in a case report.
|Incidence of side effects.||Side effects were temporary and none were clinically significant. (transient maternal bradycardia, short lasting uterine contraction).|
|Outcome of pregnancy.||No effect on fetal heart rate.|
|No late side effects -100% live born infants and no evidence for fetal growth retardation.|
|The effective dose of Adenosine seems somewhat higher during pregnancy, possibly due to the expanded vascular volume.|
|This study failed to find any evidence for an unfavourable acute effect of Adenosine on the fetus.|