[1] Green Lane Hosp, Dept Cardiol, Auckland 1030, New Zealand
[2] Green Lane Hosp, Cardiothorac Surg Unit, Auckland 1030, New Zealand
[3] Green Lane Hosp, Dept Clin Physiol, Auckland 1030, New Zealand
[4] Green Lane Hosp, Dept Clin Physiol, Auckland 1030, New Zealand
[5] Wellington Hosp, Dept Cardiol, Wellington, New Zealand