[1] Rawalpindi Med Univ, Dept Med, Rawalpindi, Pakistan
[2] Fdn Univ Med Coll, Dept Med, Islamabad, Pakistan
[3] Dow Univ Hlth Sci, Dept Med, Karachi, Pakistan
[4] Royal Brompton Hosp, Dept Cardiol, London, England
[5] Imperial Coll, Natl Heart & Lung Inst, Dept Cardiol, London, England
[6] Baylor Coll Med, Dept Cardiol, Houston, TX USA
[7] Sorbonne Univ, Pitie Salpetriere, Heart Inst & Act Grp, Paris, France
[8] Natl Coll French Cardiologists, Paris, France
[9] Kaiser Permanente Northern Calif, Div Cardiol, Oakland, CA USA
[10] Kaiser Permanente Northern Calif, Div Res, Oakland, CA USA
[11] Univ Calif Los Angeles, Ahmanson UCLA Cardiomyopathy Ctr, Div Cardiol, Los Angeles, CA USA